Tuesday, January 17, 2017

Before It Could Move

On Friday, I wrote about setting up to tear down the G0704.  And on it went. 
I cut out the marked square I showed, 1-1/4 on a side and cleaned it up.  I cut it out by drilling a lot of holes, using a 1/4" bit and an AC powered drill.  I started out with my battery powered drill but it was just obviously weak for the task and I thought I'd try the "big" one.  Night and day difference, but it has a label rating of 1-1/4 HP while the battery powered one never mentions power.  I cut the web out between the holes with both a battery powered reciprocating saw along the sides where the blade fit, then switched over to an AC powered jig saw which also made short work of the sawing.  There was some really irregular looking junk in the casting on the back of that channel you see (out of picture at top center) that I thought might limit the motion of the ballnut and table, so I cleaned that up with a grinding bit on my battery powered drill. 

The next step was to take the motor and headstock off.  This ends up weighing 50-ish pounds (rough guess).  I found a guy on YouTube (N1BPD) who had a video of taking the motor and Z column off and then another that showed him building it back up
Which leaves the base and column as the only pieces on the tool cabinet/stand.
On to taking off the column and here's where I hit a dead end.  There are four large socket head bolts in the base of the Z column holding that cast iron in place.  They take a 10mm Allen key, and as luck would have it, I had two options: a ratchet set from Sears with the novel feature that most of the sockets will pass any length bolt through them, and a nice, tool steel, Allen wrench set's 10mm key.  Two of the bolts were moveable and I got them loose, but the other too resisted everything I could do to them.  At one point, I actually tried to stand on that 10mm key.  Since it was Sunday, I said Uncle and went to think about it and figure out how much I was going to have to pay to break those two bolts loose, while watching the Packers/Cowboys playoff game.

It ended up being fairly cheap, because Mrs. Graybeard convinced me to try an adapter to mount the hex key socket on my 1/2" drive breaker bar.  Thankfully, that worked and I was able to pull the Z column.  This was right after I had watched the video where N1BPD built up his Z-axis and got it running.  I decided I had all the parts and had been basically ready to do the modifications on this for quite a while, so why not do it and get the system running?
This pic was while putting the Z-axis ballnut mount in place.  I've written a lot about this part.  The motor mount and standoffs were the parts I made for the original approach I was taking, before I switched to the ballscrew approach last April (I think).  I think I made them about a year ago.
If you look carefully at this picture, you'll see something strange.  There's a 1/4-20 nut on each of the round, threaded standoffs.  When I first built this, the motor quickly jammed and during troubleshooting, I realized the motor wanted to be about an eighth inch farther away than the standoffs allow.  A quick check of the relevant drawing said they were supposed to be 2.000 inches long, +/- .005, and they were.  Rather than make new standoffs, this was a quick fix.  It passes a 10-32 screw to mount the motor and looks neater than a stack of washers.
Tonight, the base is remounted in my wooden "boat"; the chip tray I built last summer and that has been sitting along the wall while I got to this point.  I had always envisioned trying to hold the full mill, or parts of it, over the chip tray with a crane and struggling to get it in position.  Broken down this far, it's just a 50 pound-ish hunk of cast iron to set down in the tray, finagle into place and bolt down.  I could use to seal the base so that cooling fluid can't run under it.


  1. Drilling and cutting cast iron is just such a joy....

    I haven't machined much of it other than porting and polishing several dozen cylinder heads with a die grinder, along with deburring a pile of engine blocks so the casting slag and flash wouldn't bust off and fall in the oil pan.

    1. It's nasty stuff, for sure. The chips are like 60 grit abrasive grains. Big, sharp, nasty grains.

    2. I actually like working with good cast iron. It is not sticky or gummy, machines well, and can be hand scraped to a close fit.

      A tip on stuck bolts- a short sharp impact AKA hammer blow will break free many fasteners that refuse to give- and a short piece of pipe makes putting force on an allen wrench a lot easier, even if it does not add leverage, it cushions the hand.

    3. Do you have the bigger chips or drill cuttings adhering to everything made of steel, as if they're magnetized? Is it just that I don't have "good cast iron"?

      Yes, the fact that it isn't sticky or gummy is good. I've never done hand scraping, but several pieces in the mill clearly are hand scraped. It's also kind of pretty when it's ground and finished.

      On the stuck bolts, the heaviest hammer I have is only 2-1/2 pounds and I did whack that allen wrench several times with it. The 1/2 to 3/8 adapter I bought wasn't much more than a foot of black pipe at Home Despot and I'll use it more in the future.

    4. https://www.lawsonproducts.com/Drummond/Open-Shut-Penetrating-Oil/DA7671.lp

      Not sure if I posted this for you before, but that stuff works unbelievably well. Worth having a can around, and a great gift for anyone who has to deal with frozen fasteners. Found out about it a few years ago when I was trying to unbolt the catalytic converter from the headers. Stainless steel bolts and nuts that had galled. No room to get any real leverage, so I though I was going to have to either grind off the nuts - hopefully without getting into the flanges or anything else - or find a nut splitter. Went over to my neighbor to see if he had a nut splitter, since I didn't look forward to grinding overhead with the car just on jack stands. He didn't, but he loaned me a can and suggested that I try it. I doubted him, since I'd seen my share of galled SS fasteners out at KSC, but I figured it was worth a shot. Sprayed it on all six fasteners and went in the house for a 5 minute break. Came back out and put the wrenches on the first fastener, and it didn't move. Told myself that's what I expected, and was about to give up but decided to try one of the other two fasteners on that flange. Which then came apart reasonably easily (I had tried all six before using the Open & Shut with no success). Tried the other four, and three of them also came apart. Sprayed a second shot on the last two, waited another five minutes, and they came apart as well. Now there clearly was metal transfer between the bolt and nut on each of the fasteners so they weren't reusable, but that is to be expected from galled stainless.

      I have loaned the stuff to a number of friends who were at wits' end with seized fasteners, and each time it has done the job.

    5. You know, I think you must have told me the story because it sounds awfully familiar, but the bottom line is I don't have any of it here. I should do something about that.

      In my mind, I thought of penetrating oils for this and said, "this isn't rust, it's been under air conditioning since I got it and under cosmoline since they made it, but might be gummed up with something". I did spray some WD-40 in there and let it sit overnight, but I still couldn't budge the bolts by hand until I got the longer lever arm.

  2. Good sense to move the heavy stuff in smaller bites, and it gives you a chance to clean areas that haven't seen the light of day since they were put together.
    The 1/4-20 nuts could be replaced by knurled aluminum spacers when you get free time ("free time" giggle snort). The knurling would accomplish nothing but would look really cool. And give you knurling experience before you need to use it.
    Great progress.

    1. In retrospect, it might have been a bit smarter to try and figure out why the ballscrew seems to be sitting an eighth inch farther up than Hoss' design seems to want it.

      But you're right about needing some practice knurling. I should do that someday when I have some "free time".