Building Up The GB-22

By now, I'm sure that most people have heard about Mark Serbu's GB-22, a single shot, 22LR pistol.  Mark makes the argument that this could be considered the worlds simplest gun.  It has four basic parts: the frame, the slide, a barrel and a spring.  Mark basically introduced it to the world through this video, which immediately gathered an enormous following with the video being viewed over 1.2  million times before someone pressured YouTube into taking it down. 

Mark is the head of Serbu Arms, a small company in Tampa, Florida, probably best known for a bolt action, single shot 50BMG rifle called the BFG-50 (and, yes, BFG stands for what you think it does).  He had the idea that it would be fun to make a dirt cheap and simple gun to turn in when the gun buyback programs come around.  If it costs $25 to make a gun and the buyback will give you a couple of hundred, you've made out well.  Do they offer that much?  We don't have gun buybacks around here, so I don't know.  Mark made a single shot .22 from a piece of waterjet cut steel, a 1" square bar cut into two pieces and a few other parts.  Naturally, everyone flooded him with "we want plans" and "we want kits".  I ordered plans as soon as they became available.

Does it make sense to make a gun for a buyback?  It depends on how functional you want it to be and on what your capabilities are.  If doesn't have to fire at all, or doesn't have to be accurate, I bet you can make one fairly easily.  Can you rifle a block of steel with a hole in it to create a .22 barrel?  Ream a chamber for it?  That would save you a lot of money, if you already have the tools and don't have to buy them.  That leads to asking how much does it cost to make a GB-22?

With the prints in hand, I went to Online Metals today to figure out what it costs to make this gun.  The single most expensive piece in this gun is an apparently nicely machined barrel I found on eBay (the seller was listed by Royal Nonesuch).  This is the part where if you can rifle the chunk of steel, you can cut the cost of the GB-22 by about a third.  The next most expensive piece is the frame, cut from 3/16" 4130 steel.  I've got to assume Mark had some sheet lying around, but I sure don't.  I spent a bit of time getting some of Mark's drawings into Rhino3D, and after some playing, determined it's possible to get four GB-22s out of one 12x12 sheet of 4130 steel.  That gets the cost of a frame down to $11.96 plus shipping, compared to $21.25 for the barrel.  Everything else is rather cheap. 

If that's enough steel to make four GB-22s (and I believe it is), each one will cost $53.59 in materials alone for the gun.  I swagged $2 each for some hardware and the recoil spring.  That is purely PFA.   Would you sell one to Bloomberg for $50?  Not me.  $100?  I think any reasonable hourly rate makes the gun worth more than that, unless you have a really well automated shop. 

Two of the guns Mark made, with fancy Delrin grips, and one with optics on it.  Anyway you look at it, it seems like a fun little project. 

To me, the purpose of the GB-22 is for fun.  Doesn't everyone like plinking with .22 all day? 

The reason to make one is because we can.  BTW, search on GB-22s on YouTube.  There's a few videos of updates and changes, including a .380 version (beefed up and made of stainless) along with a closed bolt version from Mark that ejects its own brass.  Most of the time.

GB-22 Progress is at a Crawl

A couple of GB-22 posts ago, I asked how to go about testing something like this.  The suggestion that made the most sense to me was to pop the bullet out of .22LR round, dump the powder and just see if I can pop the primer.  Sounds like a plan.

But first I had to build it.  Rude mistake/awakening: none of the ballpoint pen springs I could find were long enough. They also wouldn't drop the firing pin all the way.  About the same time, I was going through the prints for the umpteenth time looking for hints on what the spring needs to be.  In the original drawings Mark Serbu put down two numbers with the spring.  I just assumed it was some sort of in-house number for the spring, but then asked myself why there would two numbers.  A web search for the two numbers revealed that one of them was an MSC stock number for a spring.  They came in bag of 12, which I had to order.  I was able to assemble the gun.  All except for one last thing I'll get to.

Clearly not finished, but much more "finished" than the last post that showed it on the milling machine after being cut out.  I went over the frame with a file, cleaning up all the edges, squaring up some features that milling rounded off; generally doing light finish work  Along the way of assembling it, I found a couple of places on the other pieces where I needed additional file work, but nothing major.

There are two real differences between my implementation of the GB and Mark's: the firing pin and the barrel.  Mark used a 1/16" dowel pin for the pin.  Not wanting to play the shipping-costs-more-than-the-hardware game, and having a box of 100 1/8 dowel pins, I figured I'd grind one of them down.  It's pretty symmetrical, and centered in the hole.  

The other difference between my version and Mark's is that he didn't use a separate barrel: he rifled the 2-1/2" long front piece of steel and reamed a chamber.  I am not set up to rifle barrels, so I bought one. That raised the issue of just where to seat the barrel.  Mark's drawing shows the back of his barrel chamber recessed for the rim, so that the round would be flush.  Re-watching his videos a bunch of times, the shell appears to be sitting on that surface, not flush with the back.  I spent a while with some fired .22 brass trying to hold the barrel in varying positions and see where the pin seemed to make a good solid dent.  Not surprisingly, it seemed to be best when the barrel was farther back.  I epoxied the barrel into the rectangular barrel holder so that the back of the chamber is flush with the holder.

Old joke in quality control:  Designer puts a note on drawing "Build in accordance with MIL-TFP-41C".  QC Inspector says, "What Milspec is TFP-41C? I've never heard of that".  Designer replies, "Make It Like The F***ing Plans For Once!"  I didn't follow MIL-TFP-41C.

With the GB-22 now built, it was with some trepidation and excitement that I pulled a .22 bullet, dumped the primer and chambered the brass.  I pulled back the slide, pulled the trigger and ... nothing.  No pop.  Tried again.  Nothing.  Thinking I should verify that I didn't somehow dislodge and dump the primer, I put it in a junky old .22 revolver I have, and it popped with one hammer drop.  No primer issues; the problems are purely with the GB-22.  With no other information, I pulled another .22 round apart and repeated.  On the third hammer drop, the round popped.  So one successful primer pop out of five or six trigger pulls.

The round that fired on the third pull.  It's difficult to see, but the indentation that's closest to the rim isn't the one that fired it.  The second and third indentations push into that outer one.  Do I need a stronger spring? 

Before I'd be comfortable taking the gun on the 40 minute drive to the my range, I'd like to resolve a couple of issues.  The first one is the obvious: it shouldn't take five slide drops to fire a round.  I notice in the YouTube videos that it's not that unusual to need to pull the trigger twice.  That would be a big improvement.  The second things is the general fit of the slide.  If I tighten the 10-32 screws in the slide all the way, the slide won't move.  That sounds like there are some burrs or "something sticking up" on the slide that's keeping it from sliding.  The two of these together sound like general "fit or function" improvements.  I have some troubleshooting to do before it's actually usable.

A Little GB-22 Update

Let me lead with the conclusion: I'm not done yet.   

On the other hand, I'm very close to making the last piece, the frame itself.  All of the other pieces are cut and ready, mistakes have been left in place, and recovered from as best as can be.  The frame is to be cut from a piece of 3/16" thick steel and looks like the brownish piece here:

The turquoise colored piece is there to take up room, so that when I tell my CAM program to make tool paths to cut that frame out, it doesn't waste time cutting away that area.  My plan is to cut the main outline out with a 3/8 square nose cutter (End Mill) and leave a bit of a skin on it - about 25mils thick.  This cuts away the majority of the frame, cuts away most of the metal inside the trigger guard and that large open area in the top of the frame, where the slide goes.  This gets followed by another machining operation with a smaller cutter, 1/4", that gets everything except for the area around the trigger and that small gap extending to the left.  The small slot between the trigger and the frame will get cut with a special cutter bought just for that.  

I hold this on the machine to cut with those screw holes in the handle: 10-32 screws threaded into a plate that holds it for the cutting.  Up in the frame picture, around where the barrel mounts, you'll see four 1/8" holes.  Those line up with matching holes in the barrel holder and 1/8" spring pins make the mechanical connection.  Since 1/8 is in that awkward range that's too large for a #4 and too small for a #6 screw, I'm undecided on how to firmly attach those holes to my tool plate.  Today, I did a test cut to ensure the system could hold a piece of sheet metal down, withstand a generous cut (in aluminum), and come out the right size.  Because the piece of 1/16" aluminum I had was too small to cut the entire outline, only one of those four was available, so I added two special tooling holes to hold the plate in place and used the spring pins as fasteners.  It was all rock solid.  Those extra holes are visible in this picture on the left side of the frame and just in from the right edge of the frame, below and to the right of the real pin hole. 

This is the result of the test cut and came out as expected.  My next move is to go to on to the steel plate. 

I showed the barrel and holder a month ago; here are the three parts of the slide, the sides and the shorter middle piece.  Note the fancy cuts on the left edge of the short piece.  That had to be done by the CNC and tested out to make sure it worked.  The two long pieces, BTW, are not supposed to be beveled on the end facing the camera.  Oops.  Purely cosmetic, so "no harm, no foul".  Since I don't have metal white-out, these will stay that way. 

I'm pretty bad at estimating how long it's going to take to finish this, but I'd hope to get the first rounds through it this week.  I had no idea what to use for the spring that drops the firing pin onto the round (the firing pin is just visible as a nub above the centerline on the right hand piece).  I found a few bad ballpoint pens around here and grabbed the strongest spring to try.  I need some grips.  In the CAD world, I took a pair of 1911 grips and modified the hole spacing to fit the handle, since 1911 drawings are widely available.  Scaling the whole grip to make up for the hole spacing being different made them too narrow, though, so I need to start over.

How do you test a pistol you've made?  How do you fire the first round?  I'd like to go to my club range when nobody's around and try a few different things.  Maybe the typical "long string"?  I have some subsonic .22, and that might be quiet enough to use inside the shop.  Just to make sure the spring is strong enough.  A subsonic 22 shouldn't be any louder than a nail gun or a hammer, right? 

Some of you may be unaware that Mark came up with a closed bolt version of the GB-22.  I haven't heard anything about plans being available, but I signed up for the mailing list, so I'd hope they'd let those of us who bought the originals know about that.  Along another interesting path, the ECCO Machine video channel upgraded the pistol to a .380 centerfire, the GB-380.  People are having fun with the basic idea of the GB-22; this guy answers my basic "how do you test it?" question by firing a blank in his shop. 

Time to Recycle the GB-22?

I was just going back through the blog looking for anything I've written on the GB-22 and it doesn't look like I posted anything since I finished it - for the first time - at the end of May. 

According to the in-process pictures I've got on my drive here, I played with it until mid-July when I gave up and thought I'd let it sit until I could figure out what to do next. 

The GB has one overriding problem.  It just doesn't work reliably.  It doesn't really work at all - the cheapest, crummiest firearm you can find works better.  If I had to blame it on something, it looks as though the slide doesn't slide forward fast enough or hard enough to fire a .22 round.

All of my tests have been with the same box of ammo, a box of Winchester White Box 555 that I've had since before the Great 22 Scare a few years ago.  I drilled a hole in a piece of 3/4" thick oak that's smaller than the rim, but that fits the brass snugly.  Push a round into the oak, pull the bullet with pliers and dump the powder into a plastic bowl so that all that's left is the primer.  What I'm doing in the shop is dropping the slide on the primer.  It's frequently not as loud as a hammer blow on a nail or piece of metal.  I've had rounds go off that I haven't even heard, and only when I pull the brass do I realize it's black inside and smells of the primer having been ignited.

I've had the occasional round that fired on the first drop of the slide, but I've had others that I can drop the slide on as many as 10 times without them going off.  I then test those in a .22 revolver.  Of the 50 or so rounds I've tested this way, maybe two that didn't fire in the GB also wouldn't fire in the revolver and in one of those the primer had broken into chunks that fell out in my hand. 

Work for the last few months has focused on getting the slide to move faster.  Concerned that the firing pin wasn't leaving as deep an impression as it should, I spent some time trying to remove the original firing pin and replace it with one that is shaped more like the pin in a 10/22 (by the imprint it leaves in the brass).  The pin was bonded into its piece of the slide with red LocTite and nothing that I did would break that free, including putting it in my gas oven at 550 for an hour.  I eventually drilled a hole on the opposite side of the chamber and put in a second firing pin. 

The prints I bought say that the frame should be ".003 to .010" under thickness" of the part of the slide that holds that firing pin.  Both of those pieces are nominally 3/16 thick, which means 0.1875".  The mill tolerances, though are such that (I suspect) Serbu's sheet came in thinner than his slide piece, while mine came in thicker.  My slide is .188"; the frame was .191 or .192.  That meant I needed to reduce the thickness of my frame piece down as much as .014. Short of using a surface grinder, how can one do that?

The accepted answer is to put the metal frame on a sheet of rough sandpaper and sand it down.  My first attempt was using a Dremel-like tool with a grinding wheel.  It ended up being impossible to keep the area flat, so on to the sand paper.  First, I wrapped a 1-2-3 block with 150 grit sandpaper and worked on it for several hours.  I successfully thinned the frame.  Somewhat.

All measured values with a B are before the hours of sanding and A values are after.  You can see that there is improvement, but not everything is ".003-.010 under" the 0.188 slide.  At this point, I was running out of sandpaper, but tried taping some to a work bench and just sanding that area.  The problem is that it takes a long, long time to remove a little metal and I was just getting nowhere.

There was a pause here to try to troubleshoot how fast the slide moves, but I was unable to find a camera with fast enough exposures to make meaningful measurements.  This was the end of June.  Tests at this point showed the same problems.  Some rounds would fire with one or two drops of the slide, others would never fire, for no obvious reason.  So I said , "*&!% it" and I'll get to it later. 

With the eclipse trip over and no other distractions, I decided it was time to address this again.  My plan was to resurrect my fixture, put the frame on the big mill and thin the frame out with a large cutter.  I would zero the mill's Z (vertical) axis where the frame is the thickest (I chose the red circle on that drawing), then take off .001 at a time until it was uniform thickness or at least being cut the whole way around.  If you look at those numbers, you'll see the most important places to cut are both ends of the travel.

I did a careful setup on my tooling plate, added a couple of threaded holes for 10-32 screws so that I could use some of the Sherline hold down clamps I have.  This picture is after I did the cutting, but shows the clamps.  If you look closely, you can see machining marks over most of the path of the slide, except for a little spot in the skinny beam that holds the trigger; the area visible just above the bottom clamp. 

I started in the upper right of this picture, and used a 1/2" diameter end mill that I had zeroed on the handle where no sanding or anything had been done.  I lowered the cutter until it just touched the surface there, then dropped it .001 and made a cut counterclockwise around the rectangle.  On the first pass, it cut in that corner and only a little of the top; it didn't cut over much of the path.  I lowered it .001 at a time until the cut was continuous - everywhere but the trigger seer.  I know that's too thin as it is.  You can see the cut marks show that the long, thin, spring beam wasn't touched over about half its length.

The total depth of cut was .007.  Originally, the tool path didn't cut the leftmost portion of the frame so it had a .007" step there.  I cut the left end of the frame to the same thickness as the rest of the area where the slide goes. 

After puzzling over what to do to confirm it, I thought the most reasonable thing to do would be the acid test: put it together and try to shoot some primers.

Not even the slightest bit better.  The first primer popped on the third slide drop.  Out of six rounds not one more primer would pop.  All of them popped in the revolver.  Midway through the test, I added some oil to the frame to see if that helped, but nope.

 So I took it apart again and got the micrometer to remeasure it.

You can see the thickness go down in each set of measurements Before, After and today's Thinned.  Furthermore, while the frame isn't the same thickness everywhere, (1) with one or two exceptions (on the bottom set), you can see that the measurements are pretty much really .007 thinner and (2) there's less variation in the measurements. The top is .1758 to .1787, so just under .003 variation (vs. 007 to start).  The bottom is .1833 to .1796, or almost .004 variation.  To be honest, those measurements on the really thin portion of the trigger spring beam are really rough.  The beam is a little rolled over and the exact thickness I get depends on exactly where the micrometer sits.  Consequently, I don't trust the middle measurement on the bottom or the one to its left. 

If a "good" frame is ".003 to .010 under" the thickness of the center section of the slide, it should be between .185 and .178.  It's virtually all there; but a little too thin in the middle three measurements on the top. 

So with the frame the right thickness and the GB-22 still a steaming turd, what's next?  Is it time to disassemble everything and put it my scrap box?  I found and bought some stronger springs, but that didn't work back in June when I tried them.  I could try one again.   Otherwise, it seems like a total redesign might be in order.  If that's even remotely worth it.  Any other suggestions would be appreciated.

The Corruption is Stunning - Part II

This time, add in-your-face arrogance.  The BATF, embroiled in the Gunwalker (aka Fast and Furious) scandal, is trying to push through silly restrictions on the purchase of long guns.

Under the proposed rule, gun dealers would have to report sales of two or more rifles to an individual at one time or during a period of five business days if the rifles are semi-automatic, with a caliber greater than .22 and detachable magazines...  (emphasis added - GB)

This proposal was out for comment in December, and I wrote them asking what "caliber greater than .22" meant.  Do they mean .22 long rifle or .22 short?  Is a .22 magnum larger than a .22?  Is .22 Hornet larger?  .22 WRF?  What about .22-250, .22 Swift, .22 Cheetah, .22 BR Remington, .22 PPC...?  I see a big future for .204 Ruger if this idiocy is passed.  It's smaller than .22 any way you measure it, but can go around 3500 fps.  Business opportunity: .204 Ruger uppers for your AR lower.

This idea that Mexican drug gangs come into the US, spend hundreds of dollars for a semi-automatic AK-47 in American gun stores, when they can get fully automatic versions in Guatemala for $25, is insane.  Cables released by Wikileaks verify that the majority of the arms the cartels use come from Central America, not the US.

Yet one of the cables maintains that 90 percent of the heavy armament Mexican security forces seize from cartel gunmen comes from Central America.

Heck they probably get guns given to them by corrupt Mexican Army members, or steal the AKs from the Guatemalans.  Which makes more sense?  Come across the border into the US, and bring back a few expensive semi-automatics, or buy a cargo container and pick it up at the port?  I know that rifles do go across the border from the US - they're all being shipped by the BATF!  Whistleblowers say thousands of guns were involved in Gunwalker, making the US Government the largest known runner of guns into Mexico.

According to Mike at Sipsey Street:

It was first published in December and had a 60-day comment period that garnered almost 13,000 responses. About 30 percent opposed the reporting requirement and 70 percent favored it, ATF said.

Looks like a concerted effort by the antis - Codrea says it was Mayor Bloomberg; also looks it's time to comment to BATFE again.  Care to join me?

Excuse me, ma'am, but where did you get that AK?

Hmm.  Maybe I should try to lobby them for my version of common sense gun laws.

Machining The GB-22 Is Done - Pic Intensive

Just an update on the progress on the GB-22.  A really good question is, "what's taking you so long?" and I don't have a good answer except that I'm not a real machinist, I just play one on the Intertoobs.  It's taking me time to try to decide how to do things so that I break the least amount of parts.  Hopefully, none of my work holding schemes fall apart and send dangerous projectiles around the shop.  Also hopefully, I don't break delicate tools.  Well, I achieved the first one. 

My concern is that long "diving board" spring that forms the trigger.  It's a piece of steel about 1-7/8 long and 1/10" thick - that ends in a big, chunk of metal 1-1/8 by 3/4 (the trigger).  I didn't want that to be unsupported at any time.  In my last update, I said I'd cut four passes: (1) a 3/8 wide end mill (EM) to remove most of the metal, leaving a thin skin on every surface, (2) a 1/4 EM to get final sizes and shapes, (3) a 1/8 EM to cut the slot and back of the trigger, and (4) a pass to cut the slot in the frame for the trigger to move. 

After a lot of consideration, I thought I should cut the 1/8 wide slot first. Nothing unsupported here.

For orientation, that's the top screw in the grips, and the four things in the upper right are 1/8" spring pins.  I broke the first of two cutters here.  I was cleaning chips out of the groove and bumped the emergency stop button for the spindle.  It took me a couple of seconds to realize what was going on and hit the start button again, and when I did, I think it broke a flute off the 1/8" EM.  A little while later, the cutter snapped off, and while picking up the pieces noticed that the flute was broken off.  I was able to change bits and get going again, with just a minor delay to re-zero the Z-axis. 

Next I questioned why I should bother with the 3/8" EM pass at all.  I spent a bit of time with my feeds and speeds calculators and my CAM program getting different tool path to compare and seeing what difference it makes.  Cutting the whole thing with the 1/4" bit is slower than just the 3/8, but the 3/8 is followed by the 1/4 and the combination doesn't really seem to be appreciably faster than just going with 1/4", so that's what I did. 

This is one pass along the top of the frame with the 1/4"EM fairly deep; right to left at this point.  At the end of this operation, the extra steel was removed.  This is a milestone!  And it freed up the raw material for the next GB-22 frame.

(note my high-tech cover to keep the exposed ballscrew from getting coolant spray and chips on it - a ZipLoc bag and duct tape)

Finally, it was time to cut the most delicate cut, that 3/32 wide slot in the frame.  Like I said, this cut made me nervous, and I thought the way to fix that was to add a threaded hole in my tooling plate and add one of the small clamps from my Sherline.  I drilled and tapped a hole for the cap screw, that ordinarily rides in a Tee-nut on the Sherline.

With that in place, I needed to stick the 3/32 EM farther out of the holder than I'd like, more like 3/8" than 1/4".  This was done with a simple file that just went to points at the start and end of the slot, advance the cutter from start to end, raise the cutter above the work, go back to the start, lower it to the next level and do it over.  When I completed the cut, it was at the wrong depth, and while trying to figure out why it hadn't cut to the proper depth so I could fix it, I broke that cutter.  I was able to complete the cut and with it, machining of the frame.

There's some work to be done before I can assemble it: some file work on the seer to get the shape right, some corners to square up here and there, minor stuff.  

A minor word on software.  This is a software intensive hobby, between CAD, CAM, the Machine controller and so on.  I mentioned a "speeds and feeds" calculator that I'm using and I'm impressed enough with it to recommend it.  Speeds and feeds refers to the RPM of the cutter (or work, in the case of a lathe) and the rate that the axis motors feed the work into the cutter.  This is a recurrent problem for all sorts of machine work and has generally been solved with tables, graphs and look-up data of all kinds.  I had been getting pitches from CNC Cookbook for a while for their GWizard software and always put it off, thinking it was too fancy for my Sherline, hobby-class machine.  When I got the big mill going, I figured it might be time to take a more critical look.  They offer it on sale regularly and I picked up a copy of both the GWizard and the GCode Editor as a package last time.  It's on sale again for the next week, so you might want to check it out.   If you use a spindle motor of 1 HP or less, it's a one time purchase.  If you want to enter higher horse powers, you'll have to buy annual (or life) subscriptions.  (No financial connection or interest, yada yada)

GB-22 - First Cuts

As yesterday's post might imply, it was kinda busy around here today.   Not too busy to get the rough cuts made for GB-22 #1.  The front piece is where the barrel will go, and the three in the lower right are the pieces of slide.  The background is the 3/16" steel that will form the frame. 

The barrel kinda stands out.  It's also going to be a bit of an issue.  The gun is designed for the barrel to be an integral part of the front piece, but I'm going to have to bore a hole for it, and probably ream it to final size.  The barrel OD is about .368 (IIRC), so it would be loose in a 3/8 hole (.375).  I will probably need to fasten the barrel inside that front piece somehow.

I got the frame into Rhino last week and have a solid model to make tool paths from, but I'm not ready to cut yet.

On the refrigerator, we've decided to take the bet and replace the controller board.  When we popped the cover again today, I could smell the telltale odor of burned electronics.  I pointed it out to Mrs. Graybeard and she agreed.  It's not a healthy, pleasant smell, like a new Japanese radio (especially an Icom, Yaesu or Kenwood), and not the unpleasant odor you get out of some other electronics. Burned parts have their own individual odor.  (Right now, some of you are nodding in agreement.  Others are dreaming about the smell of their first ham rig.)

YouTube Part Deux - Narrowcasting

Thanks to commenter Ratus to yesterday's post about YouTube, a picture seems to emerge to me.  Ratus points out that Chris Bartocci, of the Small Arms Solutions Channel has been a victim of YouTube. Chris writes:

On March 23rd we received our first strike on YouTube for our Caracal CAR816 A2 video. Someone in the comments section said they were reporting the video for "promotion of terrorism" because Caracal's main hub is in the UAE. Obviously, it could not be deemed as any such promotion of terrorism and it has been appealed. However, more than 2 weeks later and we have not heard anything. Then on April 1st we received our 2nd strike for a video that was posted months ago on the Glock 19x for "violence". Again, that has been appealed. Because of the 2nd strike they will not allow us to post on YouTube for two weeks.

Chris goes on to say he's in the process of moving all of his video content to other platforms:  GunStreamer.com, DailyMotion.com, and BitChute.com. 

One of the obvious issues with what Chris says is that his videos were reported to YouTube.  Which tells me some anti-gun nut saw the video and complained.  I think that's how it's going to work.  For all the channels I mentioned yesterday that seem intact and seem to not have been affected, some SJW is going to see something and complain.  Maybe someone saw him before and was stalking his channel for something to complain about.  Maybe they're being paid to search YouTube like Soros' Media Matters pays people to watch Fox News to find something to complain about.  Maybe not.  Regardless, someone is going to see a Ruger video for the Precision Rifle and decide it's too scary because it's black.  Or they're going to see a trick shooter like 22 plinkster shoot through a string of marshmallow Peeps and complain about the violence against Peeps. There's always something to complain about. 

In the 1980s, I read a book called, The Media Lab (long out of print), about the institution at MIT by that name.  The book introduced me to the concept of narrowcasting, in direct (deliberate) contrast to the idea of broadcasting that everyone grew up with from the dawn of TV until the mid-90s or so.  Narrowcasting is just that: aiming your TV program (and the advertising that sponsors it) to a narrow audience, and not trying to reach the entire country. 

In the era of hundreds of TV channels, the idea is obvious; it was less obvious in the '80s.  Programming like that found on the Outdoor Channel or World Fishing Network, to name a couple, will never have an audience the size as the major networks get for their big shows.  Last week, for example, the top rated show on the networks was the rebooted Roseanne series with 13.8 million viewers, while the last of the top 25 drew 5.9 million viewers.  It's difficult to get these numbers for shows on the small networks because they're so small, but I think tens of thousands instead of millions.

That's what I see YouTube dissolving into.  The attraction of YouTube, the good part was (note the past tense) that it was a vast reservoir of information - like the biggest library ever imagined.  If you wanted to learn how to troubleshoot your laser printer, it was there.  If you wanted to learn how to play some song on your guitar (or piano, or ukelele or...) it was there.  It's where I learned most of what I know about how to fix my sprinkler system.  If you wanted to learn how to take apart your new gun to clean it, with better visuals than the line drawings in the owner's manuals, that was there, too. 

What made YouTube worth hanging out on was the variety of content.  I have 25 videos on YouTube; 16 are related to converting my milling machine to CNC, and of the other 9, two are gun related and the rest are videos from Cabin Fever Expo trip in '15.  Now, if I want to watch videos on a new machining tool or technique, I'll go there; to learn how to clean my new gun I'll have to go somewhere else.

Instead of being a place people will tend to aggregate, their audience will drop as people interested in (what I can only conclude will be) a continually diminishing content follow their favored content, YouTube will diminish in importance in people's lives. 

We have several alternatives to YouTube for gun related videos.  Narrowcasting.  What we don't have is several alternatives to what YouTube used to be, and that's what we need. 

My built up GB-22 (last year).  Mark Serbu's videos of his were still online last night.

Continuing Education for Shooters - II

In response to yesterday's post on an interesting analysis of shootings, commenter Reg T raised some interesting points.  I frequently turn long comments and responses into new posts, and will do so here.  Reg's points (I'm editing here - you can read the whole thing):

When trying to decide what is significant and what isn't, I usually take anything based on plain statistics and throw it out the window. ...(some content deleted for brevity - GB)

When looking to the real world, especially in the effectiveness of ammunition, I tend to think the military - especially in places where there have been many thousands of shootings, like Vietnam, Afghanistan, etc. - provides the best data available.

The Moro uprisings in the Phillipines caused the military to switch from a .38 caliber ammunition to the .45, because the .38s were frequently not effective at stopping Moro warriors, while the .45 was often effective. More recently, the military has given excellent reason to believe the 9mm is often ineffective, and a number of military units that have a choice in what caliber they use have switched back to the .45.

Any ammunition can be effective under the right circumstances, especially with proper placement. Overall, though, especially with troops that do not get the best training with handguns, nor the most effective ammunition (FMJ vs hollow points), real world results measured over many thousands of uses indicate that caliber is indeed significant.

Statistical analyses do not always prove out in the real world. They can sometimes be useful for generalizing or in determining trends, but it is too easy to miss significant data, over weigh some data, or be used to justify someone's personal agenda.

In regard to statistical analyses in general and Reg's distrust, being skeptical is good and healthy.  There's a great quote I got in a statistics class: "Statistics are like a bikini. What they reveal is suggestive, but what they conceal is vital!".  In this case, the relevant question is what these statistics are concealing.  While this is counter-intuitive, what if the .22 really was massively superior to the .45, but the statistics showed them roughly equal?  Wouldn't you want to know? You can shoot a .22 all day for $20 (I have) while $20 buys one box of .45 FMJ; it would be nice to know if .22 was better. 

Let me put forward an idea.  I'm not going to argue it's absolute truth, but I think it's logical.  Suppose there's a fundamental difference between the people the military faces and who you're likely to face in a self defense situation?  To use the statistics term, they're not the same population - and that's what his statistics conceal.

The opponents the military faces know they're in a war, and are driven by some mix of duty, honor, loyalty to squad mates and (often) religious fervor.  That means they're much more likely to keep fighting after they've been shot than a criminal is.  After all, he's probably a criminal because he doesn't have a really good work ethic.  From the self defense standpoint, the Moros are not a good model; they were a dedicated army, in a war, defending their homes and families, "reinforced" with various drugs, not a lowlife trying for an easy meal ticket. 

That's what Ellifritz is saying: that the attacker doesn't get incapacitated so much as they quit the attack once they realize they've been shot.  I've heard (can't confirm, obviously) that the Marines are now teaching new guys that they may well get shot in a battle, but just keep fighting. What Ellifritz' data is saying is that in the average self-defense situation, you're not fighting a trained Marine; once he realizes he's been shot, he's going to stop.

Put another way, the most widely accepted statistics (there's that word, again) on self defense say that there's around 2.5 million uses of a firearm in self defense every year, and that thousands of times every day, simply drawing the firearm ends the confrontation without a shot being fired.  Does it really matter if you pull a .32 or a compact .45 if they're going to back down as soon as they see a gun? 

Now, everyone has seen the stories of a drug-wracked stoner who doesn't stop until he's been hit 40 times.  The Moro tribesmen were drugged up on something that kept them going, too.  It's not like that's an unlikely scenario, either, with the prevalence of crystal meth in our society.  Faced with that situation, I'd really prefer 12 ga to the brain stem, but I'd settle for a major caliber handgun.

And the other viewpoint is also obvious: there's often no disadvantage to carrying your .45 instead of something smaller - my .45 when fully loaded weighs an ounce or two less than my 9mm XD subcompact (which has 3 more rounds).  So why not carry the big one? 

Just a Little Teaser

Any idea what that is?  

That's the barrel of my GB-22 test fit into the block that will hold it in place.  The holder isn't complete, so I'll pull the barrel out in the morning.  The only work that has to be done to it is to add four holes for 1/8" spring pins to hold it in the frame, and 3/16" slots along the middle of the top and bottom where it slides into the frame. It's part #2 in this graphic from Serbu Arms' Website.

Adaptive Curmudgeon said he loves it when I say things like this:  the barrel measured 0.368, so I thought a 3/8" (0.375) drill bit would be too big.  I was going to get a reamer in .373 (.005 oversized), but thought I'd measure my "best" 3/8 drill bit.  It was .370!  So I tried drilling out the holder, figuring that it might end up being a "test cut" that ruined the piece, and it came out more like 0.371 (it was still warm, so maybe I'll recheck it in the morning).  I'll eventually stake the barrel in place with either red LocTite or JB Weld.  I'm not sure if I'm going to cut it shorter and crown it.  Da bomb would be to cut it in two equal pieces, crown both and cut a chamber in the new half!

And not a single lesbian squirrel was even inconvenienced in the making of this post.

Happy New Year 2018

New Year's Eve is upon us, and I just want to wish all of you a happy New Year.

2017 was my second full year of retirement and was better in a couple of ways than the first year.  The biggest was that the year was free of medical issues like my emergency gall bladder surgery in June of '16.  It was largely a year of doing what we felt like doing - the privilege of retirement.  We took two vacation trips, one to South Dakota for a week with the kids and Precious Grand Daughter; the other to Tennessee to see the eclipse and they met us there.  We currently don't have anything planned for 2018, so it's getting to be time to plan something. 

Retirement is a relatively new concept in society, at best a couple of hundred years old, and it's evident that society (in some sort of nebulous, society-at-large sense) is having troubles with it.  See "underfunded pension plans" with your favorite search engine.   

I was looking at last year's blog entries to see what I was doing a year ago, and most of my posts were about completing the CNC conversion of my Grizzly G0704 - a year ago this weekend, I was completing the plumbing for the oiling system.  I also pointed out traps and tripwires that Obama was leaving for Trump.  We've encountered some of them as the year has gone by.

I had the mill built into a functional mill, completely under CNC control by February 2nd.  That quickly turned into a couple of months of tweaking and  improving.   First was reducing backlash on each of the axes, followed by completing an enclosure made from 12mm aluminum extrusion and plastic panels from the local Borg (mostly the blue Borg, not the orange).  And no, I don't know where that nickname comes from, other than I think it was the old Usenet newsgroups (kids, ask your parents).

I can't say I was done, because as recently as a few weeks ago, I talked about improvements to the rotary axis I originally added last May.  I can still think of things to do to improve its usability and user friendliness.  Then came adding an oiling system, fighting leaks until I went over to manual oiling, and finally adding a misting cooler.  It's probably best to never think of a project like this as done.

Then, of course, there was my "Son of Side Project".  Originally, Side Project was a joke because the project was putting a new side on the sawed away Breedlove guitar.  The original side was plastic left over from making the mill's enclosure.  Son of Side Project was a sequel to Side Project to replace the plastic with wood.  Now, it has a quilted maple side where the plastic was.  I gathered up the tools to do a setup on it this week and now it plays quite a bit better.  The guitar was most likely a Quality Control reject, so it needed lots of work.  The frets were uneven and had to be leveled with a file.  It probably needs some additional work.  I know the $8, eBay-special tuning machines I bought for it need to be replaced. 

As far as projects with my CNC'ed, four-axis G0704 mill, I haven't accomplished much.  I built the GB-22 but never got it to function reliably.  It's still sitting as a "one of these days" project, in pieces.  I built the Little Machine Shop wobbler steam engine.  After drilling out the flywheel on my rotary table, I took the whole thing apart and put a shinier finish on all of the parts by lapping them on finer grits of sandpaper, and/or turning in the lathe's chuck.  Put it back together to find it doesn't run as reliably as it did.  I think I took too much mass out of the Flywheel.  I will turn a new one and get it back to where it was. 

In addition to my ham radio antenna project, I have another electronics shop project, a box for a component called a variac.  This will allow me to put lower voltages on older vacuum tube equipment, at least while I get it running the first time. 

The black rectangle on the top is an AC voltmeter/ammeter like one of these and the AC outlet on the front is still under consideration.  This is going to be like my controller box for the CNC 704, with the panels laid out in Rhino3D CAD and cut out on the CNC mill.  This time it will be cut out on the big system, though.

Aside from those two, I'm looking at more projects for the metal shop, with fewer involving guitar resurrection.

Happy New Year!  Remember, if you drink, don't text and if you text, don't drive.  Or something like that. 

A Trio of Shop Improvements

As a side project, I've been working on a few improvements to the G0704 mill to improve usability and fix some deficiencies in the mill itself. 

The deficiencies were minor - chip guards to keep metal chips off of the ball screws and sliding surfaces.  It came with one between the back of the cross slide and the Z-column, but somewhere along the line that has been damaged (obviously, I must have done it, but I don't remember when); on the other hand, it never had one in the front, between the cross slide and where the handwheel used to be.  It never needed one, except for the fact that I cut away an inch or so of base on Hoss' recommendations (top picture here), and the ballscrew would get exposed when the slide was moving toward the Z-column. 

I ordered a sheet of 1/16" neoprene from an eBay vendor, cut it to size and replaced the back piece.  Then I cut a second and made a skirt for the front.  This required cutting a little piece of 1/8" thick aluminum to clamp the rubber to the front of the slide, drilling a couple of holes and making a cutout around the oil fixture, but it was an easy job. 

The rubber sheet in the back (on the right here) had split in the bottom of the trough on the right, and also split on the left where it was attaching to the cross slide.  While it wasn't gaping open, chips could get in through the openings and onto the ballscrews.  The hole in the front was a different story.  When the table was all the way to the back, there was a hole there with well over an inch of the ballscrew exposed.  You can see it in the video here.  Chips, dripping coolant, small families of illegal aliens; anything could get in there.  In one of my GB-22 posts I showed a zip loc bag taped to the fixture so that it covered the opening when the table was forward. 

This needs a little work because the sheet on the front pulls toward the column with no problems, but when the table pushes back, it doesn't get out of the way.  I need to figure out something to do about  that.  Maybe it just needs to be a rigid piece of plastic and not a long floppy piece like that sheet rubber? 

The other improvement was to add a pendant.   Sort of.  A pendant is an interface to your CNC controller program, Mach3 in my case, that is portable.  You can bring the pendant to the mill so that you can jog the position of the slide when you're working on the table or something and can't reach the computer keyboard.  Commercial pendants can be complex and do lots of things, but at least for now, I'd be happy with a small box with six switches: left - right, forward - backward, and up - down.  Some years ago, I bought a Logitech Rumblepad 2 game controller, also for something other than gaming (to control a telescope) and while looking at ways to make a pendant, I remembered I still had it.  It took some reading online to recall how to set it up, but once the computer recognized it I was able to get Mach3 to pair with the Rumblepad and program some buttons to move X, Y and Z.  

While the commercial pendants tend to hook up via cables to the computer (USB or other serial port), this one is wireless.  That means it's easy to set it down on the table, so that when I've got my head and shoulders stuck in the enclosure trying to line up something critical, I can just hit a button to move the slide.  It also works from farther away, like across the room.  I just haven't come up with a reason why I'd need it to.

It Was One of Those Days

In the shop, that is.  I guess we all have them, right? 

In the GB-22 image you can see here, there are three pieces screwed together in a stack to make the slide.  I've previously cut them to the proper size, so it was time to get the through holes drilled in two pieces and the other piece drilled and tapped.  First problem: I realized that I cut the middle of the three slide pieces too short and need to start it over.  Moved on to the two side pieces, which are thicker and longer.  Drilled the first one out to clear the screws, then drilled the opposite side with a smaller drill so I could tap it... and broke the tap off in the first hole.  After some time trying to drill the 10-32 tap out, first with a carbide drill bit then with a diamond coated bit, all I can say is... dang that stuff is hard!  No success - I may have put a 10 or 20 thousandths dimple in it.  Can't use alum because that only work when it's a steel tap in aluminum; this is steel in steel.  I could build an EDM tap burner.  Gee, that commercial machine is $1500, I'm sure I could build one for a few hundred $.  Lessee... $250 or $500 depending on what I can scrounge, and the time to build it, to save about $3 worth of steel...no, I think this one is scrap, too. 

So I'm 1 for 3 on simple, minimally machined parts.  

While trying to drill the tap out, I needed to raise and lower the mill head, so I'm using Mach3.  Out of the blue, my keyboard input stops working.  It's a wireless keyboard, and changing the batteries didn't fix it.  At one point, turning the computer off and on seemed to help, but I'm not sure. 

So, all in all, an annoying day.  One thing worked out well: I came up with a mount for my Fogbuster system.  Sort of a wooden hat rack.

The legs are a pair of 2x4s in lap joint, and the upright is a 1x4 that's glued and screwed to one of the legs.  In this view, the compressor is behind the viewer, the input hose is the dark blue one dropping below the edge of the frame, and the output of the tank is a pair of clear hoses going over the top edge of the enclosure to the sprayer mounted on the mill's headstock. 

Well, tomorrow will bring more time to mess-up some more metal pieces.  I'll be smoking a turkey in the afternoon, so plenty of time to play in the shop.

Is Google Coming for the Gun Bloggers?

I learned from Gun Free Zone this morning that John Richardson at No Lawyers - Only Guns and Money had his blog shut down.  He's the only one I'm aware of, but I can't tell from my reading list how far that might be going.  I've linked to John's blog for as long as I can remember.

I suppose that Wayne LaPierre, or one of his minions, might have complained to Google because of things he posted that are critical of Wayne, but we don't know that.  I've certainly never seen anything I'd consider out of line for a blog. 

I don't have John's contact info, and I'm not on Twatter, so I can't ask him what the story is.  When I go there, I get a Blog Gone message:

Meanwhile, I keep talking about moving off Google, dropping the blog and GMail, and signing up for a more "Do It Yourself" service, but when it gets down to it that sounds like work and I've put it off.  

I'd think they'd get me first.  After all, I tell people how to cast an AR lower - an untraceable gun! - from aluminum cans.  I have a whole series on making another untraceable AR from an 80% lower, and a whole series on making a GB-22 from plain steel bar stock. 

What did John do?  Tell the truth about the NRA?

I haven't said where I stand on the NRA "coup" stuff, but the more that goes on and the more I see, the more I agree with calls for an independent audit.  Maybe Wayne's holding off because he figures the New York attorney general will have them audited and have the New York taxpayers pay for it, instead of the NRA paying for the audit, but I'm convinced that the old adage from the business world applies here: "the appearance of impropriety is the same as impropriety."  If the NRA were a functioning commercial enterprise, Wayne LaPierre would be out.  At some point, and maybe we're already there, Wayne is already costing the NRA too much money in lost donations and lost opportunities. 

I really need to get off my butt and get moving to a new system.  Today, the news crossed my path that it's not just gun blogs they're after.  They driving traffic away from "alternative health" sites.  How long until users aren't allowed to talk about anything that isn't approved? 

Spinning My Wheels in the Shop

I see my last shop date was August 19th and here it is August 40th, so it has been way too long.  

There weren't too many parts to make to complete the intake/exhaust valve stack at that point, just a couple of valve retainers, and a couple of springs.  First, I had to press fit the valve cages into the stack of aluminum slices that make up the intake and exhaust manifold, cut the valves to length and grind them against their valve cages.  

The valve retainers are fiddly little parts; 1/4" diameter shoulder (1/32" tall) and then a 3/16" diameter by 1/16" long nub that sticks into the spring.  When it's assembled the stack-up looks like this (red arrow pointing at the intake valve retainer).

And the two valve retainers fresh off my manual lathe looked like this.  Crappy surface finish!

Pressing the valve cages into the aluminum and cutting the valves off were easy peasy.  

I've been stuck on the springs for at least a couple of weeks.  I've only made a couple of springs before but they didn't have a critical size like this.  I've always followed the step by step instructions on Dean's Photographica and they've worked but what's happening is that I wind the wire tight on to a piece of round bar, and they expand in diameter.  Say it's wound on 3/16 rod; they expand to 1/4" and the retainer falls into the spring (or screws itself down the wire ramp).  I can't seem to get the spring to a usable diameter.  It needs to be 3/16" inside diameter to fit over the valve cage and it can't be so big that the retainer falls into it.  I've tried winding onto a smaller diameter rod, but that one hardly expanded at all.  At this point, I have three that are too big and one that's too small. 

I thought my best chance would be to wind it on a 3/16 drill rod and clamp the wires securely.  To clamp the wires, I'd cross drill the rod and tap it for a couple of #2-56 screws.  Then it's clamp one end of the wire, count out the number of turns, and wrap the far end of the wire around the far screw, before putting it in the oven for heat treatment.  

I should point out that while this is on my Sherline lathe, that's just because the rod is held in the lathe chuck.  This isn't done under power: I turn the chuck by hand to put the wire on.  After the heat treatment, this one opened up to around .220, still just a bit too big.  The valve retainer slipped into the spring.

I haven't tried the exhaust valve spring, but I have some springs I bought back in the GB-22 project days and one looks like it just needs to be cut to length.

Plan B is to remake the valve retainers to be 3/8" OD with a 1/4" nub to fit inside the spring.  I don't think it matters and I've spent too long here.

Meanwhile, I'm making the muffler and searching the drawing to make sure there aren't parts left I haven't made.  I put in a hardware order to be sure I had everything to put it together and ordered an RC airplane carburetor.  I'm getting close to being able to put it fully together, if I can figure out how. 

A Machining Puzzle

I like to say that every part is a puzzle, and one of the puzzles that interests me the most is rifling a barrel.  Especially a rifle barrel.  I'll be the first to say that creating a match grade rifle barrel is a work of art on a par with any sculpture or high art you can imagine and I don't see any way that's in my future.  But what about applications where the demands aren't quite as severe, like a pistol used out to a few yards or a battle rifle used to a hundred or two? 

This is one of those "how would you cope if the system collapsed" questions: barrels wear out.  What can we do?  Stockpile barrels?  Hat tip to Weapons Man today for getting me thinking about this, after posting a couple of interesting videos of rifle barrel manufacture, although thinking of how I might rifle the barrel of the GB-22 started this thought process days ago.   

A few days ago, I ran across this interesting video of a guy who's making a .380 pocket pistol, sort of based on a Colt Mustang (I gather) that he calls the Kolt380. Take a look at this:

Now think about this: how is rifling different from an cutting an internal screw thread?  The main thing I see is that instead of "turns per inch" you're interested in "inches per turn".  Rifle twist rates are described as "1 turn in 16 inches" or 16 IPT.  Cutting threads on the lathe is a fundamental operation, with the thread TPI set by changing gear sets to fix the ratio of turns of the work to the advance of the cutting bit.  In this video, the barrel is clamped motionless and the cutter is spun into the work.  In internal threading, the cutter wouldn't rotate, the barrel would.  As a practical consideration, the number of TPI that can be cut with the typical lathe's set of gears is going to be much larger than you'd want for a gun barrel; say a minimum of 4.  A .223 barrel might be 1 turn in 7 inches, or .1429 TPI, while 1 in 10 inches, 0.1 TPI, is common for .308.  A typical .22LR is 1 in 16" or .0625 TPI.  Handguns run in the same general ranges. 

How do we get those very small TPI values?  Extremely wide range gears?  I'm guessing the gear ranges are limited by what fits in the machine.  What if we didn't use gears? What if we drove the chuck holding the barrel with a stepper motor and advanced the cutting tool with another stepper?  There could still be gears or something to slow down either rotation, if necessary.  The most common stepper motors have 200 steps per turn.  That could be geared to 400 or more, if necessary.  The ratio of speeds would be set with CNC controller.  It would need feedback so it knows the motors are in the position they're supposed to be, but rotational encoders are pretty common in CNC threading. 

Saying "let the CNC do it" doesn't let one off the hook!  There are still going to be ratios of speeds that have to be considered.  I haven't looked into this, so I can't say for sure, but I can imagine needing to run a range of speeds that might be impractical.  I might have enough numbers to start looking at potential solutions, though.

Well, this is kind of rambling, "what if?" pondering.  Something to think about as we wait to find if our long national nightmare is ending or just beginning.  Just kidding. The Deep State always wins.

Completing the G0704 CNC Conversion

To the extent that a project like this is ever "Done", this one is done and what I write from now will mostly be either what I do with it, or improvements I make to it.  The mill itself is now done.  I think all CNC hobbyists end up tweaking their machines as part of their hobby, though.

I started putting together a project page which appears in the "Special Pages" list in the right hand column.  I've moved that up to just below the Florida Gun Blogs section.  It became apparent to me that the page needed an introduction and a conclusion; this is the conclusion.

The last thing I wrote about the project was that I had a small but persistent oil leak out of my oiling system onto the floor.  Small as in 3 or 4 drops in a day.  As my last fix, I replaced the push to connect fittings with plastic barb fittings.  Because I used 5/32 OD, 1/8 ID tubing everywhere, I needed a fitting that went from 1/8-27NPT male threads to a barb in that size.  I couldn't find one, but I could find a fitting that I could adapt to and make work by using a short piece of 1/4 tubing.  It ended up looking like this, and has not dripped one drop of oil in 5 full days.

People considering building something like this will wonder if it's worth it.  In response, I'd have to ask why you'd consider building it.  Do you need it now, urgently? Are you trying to learn what's in a system like this and make one, just because?  

If it's purely to save money, it might not be the smartest thing to do.  The G0704 is $1359 today (including shipping).  Automation Technologies will sell you a ready to run, CNC converted G0704 with an Ethernet interface for $4000 (I don't think that includes shipping while the Grizzly price does).  That's paying $2620 more to have it now as opposed to working on the conversion as long as I did.  I'm not 100% sure I've captured every expense in my journey, but I think I spent close to that amount, maybe more.  That prebuilt machine doesn't appear to have an oiling system, a chip tray, and an enclosure, all of which mine does, and all of which were considerable effort and expense to get working. 

How long did it take me to build it?  I actually started in June of 2015, six months before retirement.  Once I had all the parts made for the approach I was taking, in March of last year, I switched approaches rendering all of what I'd made useless except for the Z-axis motor mounts.  I started in early April '16 and had the system running on all three axes, ready to use this February 2nd; 10 months.  It wasn't full time work, but I worked several hours every day, weekends included. 

A really good machine that has more travel than mine, is the Tormach PNC1100 from Little Machine Shop at $8500.  Tormach is industrial quality without a doubt, and I have no doubt it outperforms mine.  It still isn't complete as it doesn't have an enclosure around it and I'm not sure if it includes an oiling system.  The next cheaper Tormach that LMS carries is priced at $7000; it has less travel than mine and a motor rated for less power.  Both of these machines include things I can only aspire to at this point - automatic tool changer systems, and tool holders (the Tormach Tool System - as an add-on, it's half the price of their milling machine) and very likely more.

So I spent about what the Automation Technologies G0704 costs but ended up with a more complete system.  I also made and remade a lot of parts and got experience I've never had before with the tools.  With my $2600 or $2800 I not only bought the conversion, I bought an education.  If my only goal was to have the completed machine, it's a perfect illustration of "penny wise but pound foolish".  If that's your goal, buy one of those machines.

On the other hand, think of a mill like these as a system; a chain of parts that's subject to the adage that the chain is no stronger than the weakest link.  During the design, all of the components are chosen based on the expected use of the mill.  When you replace leadscrews with ballscrews, the table can go faster.  All well and good.  The spinning cutter, though, will only take so many cubic inches per turn, depending on how fast the spindle can cut off chips of metal without stalling.  How fast the spindle can rotate under load depends on how much power the motor is able to deliver to the cutter.  If you want to remove the most metal in the least amount of time, a CNC mill needs a faster spindle than a manual machine's.  Mine spins at 2300 max; those Tormachs can spin at 10,000 RPM.  The motor's horsepower determines how much force ends up getting put on the whole machine, which in turn affects how much the machine bends and deforms during a cut; which determines how rigid it needs to be and how big and heavy it needs to be.  Plus, I think that worrying about "removing the most metal in the least amount of time" is where industry lives, not hobbyists. 

Don't go thinking "I can put some ballscrews and nuts on this machine and it will be zero backlash and as good as Tormach".  First, it's possible to end up with backlash - I did.  That's in my list of stuff to tweak on and make better.  Second, like I said, this is a system and you're replacing parts in a system with upgrades expecting it to get better.  It's also possible you'll improve one thing and discover weaknesses in other areas.  The way I look at it, you generally get what you pay for.  The Tormach has the advantage that it was designed from the ground up to be a CNC mill on a small production line.  You don't buy the $4000, ATI-built G0704 and expect it to equal the $8500 Tormach - which itself is not going to equal a $50,000 HAAS. 

If you're the kind of person who approaches most problems with "close enough for government work", machining is probably not for you.  I don't have any measured numbers on what sort of accuracy to expect in the converted mill, but I think these are a good choice of a home machine for the vast majority of your mad scientist projects that will fit on it.  The mill as received from Grizzly was a good performer as a manual mill, and it should still be one.  You're not going to cut a titanium turbine for a 747 engine on it, but maybe you can cut one for a model engine. 

5-axis machining is possible with the G0704, but not the way I've configured it now.  I have all the parts of a fourth axis that I intend to get running soon. Maybe after the GB-22. 

EDIT 4/24/17 2025 EDT - Added the link to the project's page in the second paragraph

If OWS Is Really Against Big Bankers...

If Occupy Wall Street is really anti-big business - and especially banks - why do they keep destroying small businesses?

In San Diego, they "thanked" some hot dog vendors by vandalizing their hot dog carts, throwing urine and blood on them.  They did the same for coffee carts.

In an ironic twist of fate, the owners of pair of San Diego coffee and hot dog carts — who initially provided free food and beverage to Occupy protesters – had to shut down after demonstrators turned violent, splattering their kiosks with blood and urine.

In New York, Marc Epstein, owner of the Milk Street Cafe, had to lay off 21 out of 97 of his workers in this newly (June) opened restaurant.  It's not like he's a new owner who doesn't know how to run a place: he has been running his Boston locations for 30 years and reports this is his first layoff.  His main problem: not the protesters themselves but the inevitable rearrangement of the city's traffic patterns to avoid them.  A prime example of unintended consequences.

I feel sorry for Stacey Tzortzatos, (rt) owner of a little restaurant called Panini & Co. Breads, "across from" Zucotti park.  Protesters would come into her place to use the bathroom.  They allowed this go on for a while, but one of the useful idiots was apparently sitting on the sink and trying to bathe.  The sink departed the wall, broke, ripped out the plumbing and flooded the place.  Cost a few thousand dollars to fix.  Understandably, they now don't want to allow anyone other than paying customers in to the place to use the facilities and she gets death threats.

“I’ve been told, ‘Watch your back!’ 10 times,” Stacey Tzortzatos, owner of Panini & Co. Breads, located across from Zuccotti Park, told The Post yesterday.

She and her employees are terrified by the constant threats, which she said began after she demanded the protesters stop using her shop’s restroom as a place to bathe every day.

The final straw came about two weeks ago, when the demonstrators broke a bathroom sink, flooding the shop, and clogged the toilet -- setting her back $3,000 in damages.
...
“I have the police in here 10 times a day, [and] I’m the bouncer. I’ve been called the spawn of the devil. “It’s unbelievable what goes on in here every day, ” Tzortzatos said.

The other "City by the Bay", and seeming center of the worst violence, Oakland, has been seen small businesses hurt badly by the protests, with several businesses citing damages and extreme drops in sales.

"We are seeing serious losses of business," said Junge (public policy director of Oakland's Chamber of Commerce.)

"People have lost 40 percent, 50 percent, 60 percent of their sales."

If they really are protesting bailouts to banks and crony capitalism, and not just trying to destroy capitalism itself, the #OWS idiots are singularly ineffective.  Have you heard of a single bank that has been impacted?  I haven't - only these struggling small businesses.  The profit margins in restaurants, taverns, and the other small businesses being hit here are not large and these businesses are not "rich fat cats".  The owners and managers are probably lucky to keep the lights on.

Sure, these people have the right to protest. Absolutely, positively - without any question.  But young Ms. Tzortzatos, Mr. Epstein and all the others have a right to their livelihoods - to run their businesses as they see fit.  The occupier pigs** don't have the right to run them out of business.  It's wearing on too long and NYC has let it get too far out of hand.  Neighbors - just plain folks - are complaining about the constant drumming, the stench and the destruction of their favorite places.  Time for the OWS crowd to go home. 

But the protesters appear to be digging in, erecting three of what will eventually be more than two dozen, 16-by-16-foot military-style tents that will help them stave off hypothermia in the coming winter.

And they’ll have some entertainment today.

Music legends David Crosby and Graham Nash are slated to perform an acoustic set of protest songs this afternoon at Zuccotti Park.

**pigs?  Am I too harsh?  Judge for yourself:

Occupy Wall Street has tried to reduce the strain on local businesses by setting up three 24-hour porta potties several blocks from the park on Friday. But DNAinfo reports that as of yesterday, many occupiers didn't know they existed, and others chose not to use them. "I use a street corner, a telephone pole," 22-year-old protester Terrence Hubbard says. "I did it a couple of times in my tent when I was lazy. Otherwise, I go to McDonald's."[emphasis added - GB]

You relieved yourself in your tent?  What kind of animal are you?  My cats have infinitely more class than that.