With the mill in place I started looking into lathes. Like the milling machines, most of the lower cost lathes you can buy new these days are made in a couple of factories in China, and Seig is again the big name. Quick sidestep: lathes are usually described by two numbers, the first number is the swing or largest diameter object that can turn over the bed or ways of the lathe, and the second number the distance between the chuck and the tailstock (see below), or between tools called centers mounted in those places, which gives an indication of how long a piece of work that can be held. A common example is a 7x 12 or 14", which turns an object 7" in diameter over the bed of the lathe and 12 or 14". Exactly what constitutes a given size can be up to the company selling it. For example, one seller might sell a 7x14 that another would sell as a 7x12 because it would never hold a piece of work 14" long; they refer to the bed length and not the length with the tailstock in place. It's best to think of these numbers as rough indicators of the overall size and then compare dimensions between the different brands.
I had been leaning toward a large tool room lathe, a name typically in the range of a 12 to 13 by 36 to 40" lathe. These can be rather large machines with large, heavy motors that produce more than two horsepower (a practical limit for a 115 V circuit).
After weeks of poring over specifications and really pondering what I'm likely to be doing, I decided to look into lathes in the 9x20 class, which fits my expected work envelope with some room for comfort. I don't really anticipate working on things as large as turning brake drums, but cutting the chamber for a rifle barrel is a real possibility. To do that, most writers recommend a lathe with a bore through the headstock of 1 1/2" or more. (The barrel would stick out the left end of the headstock and the chamber area held in the chuck - a very stable position).
Also bear in mind the big truism/cliche', "How big a lathe do you need? Invariably about 1" bigger than you have".
I eventually narrowed it down to a choice between a few and then a choice between two, the Little Machine Shop 8.5 x 20, a Seig SC4 and a Precision Matthews PM1127VF-LB . At first glance, they appear wildly different in size, and the PM1127 is certainly a bigger, more powerful, more capable machine. The LMS 8.5x20 is virtually the same work envelope as what most dealers sell as a 9x20 but with a more powerful motor and power cross feed as well as feed along the axis of the part.
I set up an Excel comparison matching the accessories (dealers never spec out their machines with the same accessories) to find the final price to put it in my shop. The PM1127 ends up costing 20% more at $3182 vs. $2638 total (including delivery). In my case it came down to concluding the PM1127 is certainly more lathe but I'm not sure I'd ever take advantage of it. I've decided to go with LMS 8.5x20.
"Invariably about 1" bigger than you have".
ReplyDeleteI have the Grizzly branded 9x20 and the above is totally true. And yet, by working at the extreme end of the ways, and by using a steady rest (modified to use ball bearing rollers) I did thread the muzzle end of a ban era HBAR barrel. It was slow going but it turned (joke) out very nice.
Give a lot of thought to the quick change tool post choices, it will affect everything you do on the lathe.
Master the left hand filing skill and wear short sleeves.
Good luck,
John in Philly
You might want to revisit your decision due to the absence of a quick change gear box for the lead screw. Also, neither machine is clear on what the spindle nose is (how the chuck is mounted). Even a threaded spindle nose is preferable to one you have to bolt the chuck to. John in Philly is very right about the selection of a tool post. If the supplied tool post is not a sliding gib Aloris type, do yourself a favor, turn it into a paper weight and buy an Aloris or clone thereof. 40 years of doing this stuff talking.
ReplyDeleteIMO that PM 1127 is about three times the machine the LMS 8.520 is- rigidity and weight is everything in a lathe. Just compare the weight for starters-650 lbs vs 220. Also has a quick change tool post,quick change gear box, and a pretty nice looking cabinet. Has a 6" chuck vs a 4" chuck- (huge advantage) Has a much lower low speed, more hp, and a 7" wide bed- and a 1.5" spindle bore. It looks to me like PM decided to take some of the features of the ubiquitous 1340 lathes and apply them to a hobby size machine.
ReplyDeleteAbout the axiom- "1" bigger than you have-" that is true, but has a steeply diminishing application the larger you go-
ownerus above is correct on the chuck mounting- the MT 3 on the LMS lathe- Is that a standard on the 9" lathes? Can you get a faceplate?
The PM said "direct mount" , what is that? threads? D1-4? They come with a faceplate though.
Buy once, cry once..
By the way, I ended up with a 1340 Taiwan lathe and a 1940's VN 12 mill..
A lot there to comment on, but most importantly, thanks for the inputs, John, Ownerus and Raven.
ReplyDeleteRaven, PM compares their machine to "12 by" lathes and that seems right.
The LMS machine has an MT3 on the headstock and MT2 on the tailstock. I'm believe the chuck bolts to a plate on the spindle. There's a page on a similar lathe, the Seig C4, at Mini-Lathe.com and that's the way it's shown. The specs on that page, though, vary quite a bit from those on LMS' page, so either they're selling a newer design in the SC4, or they specified it differently from Seig.
Little Machine Shop's main line of business is accessories for all sorts of machines. They include their own (designed for/with Tormach)wedge-type QCTP in the package. There is a faceplate for it.
I'm not as wild about this selection as I'd like. It's much more capable than what I have, but not as capable as the PM1127.
Before you buy new, go to craigslist. it's full of hardcore, red white and tool room grey heavy metal from South Bend, Brown and Sharpe, Hardinge etc. for usually very reasonable (IMO) prices... careful inspection is the word(s) of the day.
ReplyDeleteSome of it has war heritage too... something to raise a little old-fashioned patriotic lump in yer throat. If they tore it out of a retiring fighting ship, it may have actually been floating around in the sea war.
I have a Seig SC4 from way back, I bought it as the road less taken when I could only find one review and the standard advice was to get a 9x20. The SC4 marked "8x12" is nice. It's much nicer than what I had before, which was a tabletop drill press and a file. But when you want to cut threads? You want to turn a shift knob on a gearbox, not hand assemble a gear train by screwing a Spirograph to an erector set.
ReplyDelete3X the weight is not a 20% difference, it is a huge difference. With the lighter lathe there will be cuts you can't make, fine cuts, and cuts in harder steels, because the lighter lathe will flex instead of forcing the cutter to penetrate. Crank the feed in until the tool bites, and it digs in too far and something bad happens. This still happens even if you sharpen your cutters with a diamond grit file and inspect them with an eye loupe. You just can't get there from here, just like you can't tow a big boat with a four cylinder Honda. You might think you could tow it, just slower, but get to the put-in ramp and won't work at all.
At the time I bought my 8x12 it was far more than 20% additional to get the next alternative up. I don't regret the 8x12 in the least. That said, my advice to you is getting the 3X HEAVIER one, with the GEARBOX, is a no-brainer.
housefitter's advice is well taken, although there may be wide differences in machinery availability in different areas- but you never know, eh? Every once in a while among the worn out and overpriced, a real gem slips in. On a lot of older industrial equipment there may be power issues AKA 3 phase.
ReplyDeletePractical Machinist forum is an excellent resource if you want info on restoring machines. After replacing countless parts and scraping the ways on the vn12, I am very sure if I was paid $10 an hour I could have gone out and bought a brand new Asian machine. Although it was a rigorous course of study and I learned a lot.
On the subject of weight.
ReplyDeleteFor the machine shop, or for the productions shop, weight translates to being rigid, but for the hobby or home machine tool user, weight can have an adverse effect, how will you get the machine into your house, basement, garage?
My father was a real machinist, I am not, and when I asked his for his input on buying a used lathe, he stated that a lot of used lathes are on the used market because they are worn out in the first foot or so of the ways near the chuck. Thus ravens statement on the time spent scraping the ways.
And when you decide you need a planer gage, I will mail you one of mine, I got two of them from my father and I still have never used them, (or quite understand how to).
But when I use my father's micrometers to measure something I am working on, I feel good and I feel a powerful connection to my deceased father.
John in Philly
I second looking on Craigslist or eBay. There is a lot of good used machinery out there although, sadly, a lot of it is being scrapped. Yes some is worn out but much is still quite useable. My own first lathe was used a 9x30 South Bend purchased 38 years ago. I still use it. It was a little worn on the ways near the headstock but still does accurate work. A WONDERFUL versatile little machine.
ReplyDeleteI've added several used machines in the ensuing years. Weight seems to scare people so larger machines tend to be cheaper since the guy with his pickup and two buddies doesn't know how to deal with it. A little innovation can usually handle it. I once unloaded a 4000 lb mill with a two ton chainfall on the limb of a big oak tree.
Even 3 phase isn't that big a deal. Rotary phase converters can be bought or built and open a lot of options in machine availability. Odd voltages and frequencies can complicate this of course.
If buying a new lathe today, I'd go at least a little bigger than your choice (it's easier to do small work on a big machine than the other way around and you're unlikely to go TOO big), get some form of quick release spindle nose for the chuck ( cam lock or threaded spindle nose) a quick change gear box for the lead screw, and make sure spindle speeds are easy to change. The big hole thru the spindle on some of the newer machines is a big plus. Whatever you end up with, developing the skills on THAT machine is a big part of the picture.
I like the LMS guys, but I'd go with the 1127 if you are set on new.
ReplyDeleteOTOH C list is your friend. There is a 10" Southbend with tooling in Lakeland for $1600.
I'm a machining newbie and purchased a used Jet 9X20 just a few months ago. This morning I fitted it with a very well built "Bostars" axa quick change tool post kit that I bought from CDCO for only $118.00 and that was for the post and 5 tool holders. I also built a 4 bolt compound holddown and with the 4 bolt and the QCTP, I think that the rigidity will be much better than before. Now, if I only had a "small" milling machine, I think I would be set.....until I can afford larger machines..
ReplyDeleteGraybeard,
ReplyDeleteJohn's offer on the planer gage is sweet. Very useful device for measuring all sorts of things. Use mine more than I ever thought I would. Excellent for setting up machinery of all types.
Try this website for advice on buying :
ReplyDeletehttp://www.lathes.co.uk/page2.html
and individual lathe types
http://www.lathes.co.uk/page21.html
Plus click on the Lathes Tehnical Advice at the right of this page for a LOT of info regarding how lathes work, quick change tool posts etc.
http://www.lathes.co.uk/
Phil B
One of the big disadvantages of teaching yourself something is that you don't know that you don't know. My current lathe doesn't have a gearbox, so it never occurred to me that not having one should be a deal breaker. In the use of my lathes, I've only cut threads a handful of times, but didn't find it to be a big deal to put the gears in place to do so.
ReplyDeleteBasically, the LMS looked like a bigger, more powerful, better-made version of the 7by or 8by mini-lathes so many people use, so that it seemed like a pretty safe choice. Despite their reputations, a lot of people do a lot of very serviceable, very good work on those mini lathes.
Something like a Grizzly 9x20 is way cheaper than the LMS 8 1/2 by 20 so you can bet I thought about that a lot. Basically, I've read some disappointing things about them, although most people seem to say the Jet machines are better (same factory, different paint - that story). Jets are more than the LMS 8 1/2 x 20.
And speaking of not knowing what you don't know, I didn't know what a planer gage was until a few minutes ago when I looked them up. John, raven's right: that's a heck of a nice offer. BTW, John, my dad wasn't a machinist, but I understand the connection you speak of. I have my late dad's pistol; a little .25 Auto pocket pistol from the mid-60s.
RE: size and capability. Not about lathes, but the decision was wrestled with about that topic on some tooling here. Job analysis was done, tooling was obtained to do ~90% of routine stuff, with planning to hire out the infrequent remainder to those with larger (and much more expensive) tooling. Looked real good on paper.
ReplyDeleteMistake. Scheduling and training issues caused massive problems. The larger jobs were, by definition, more complex, and unique. Delays caused by vendor scheduling issues were a killer, and having to train vendor personnel on how to do the complex operations we needed performed only rarely (sometimes only once, but skills do build on previous skills) was a death sentence. With the right tooling that expertise would have been developed, maintained and cultivated in-house. Learning curves are sometimes very steep, and having to climb them repeatedly is a hemorrhoid of the first order.
Buy bigger. It'll look like a waste until that one thing pops up that makes it all worthwhile. Sometimes you can work around tooling limitations but until you have to do that a few times you won't know just how restricting it can be.
And many of those issues are even worse for a small hobby/prototype shop. Even finding a shop willing to do R&D or one-off type projects is tough and even then it will cost cubic dollars. Might as well spend that on more machine.
DeleteGraybeard,
ReplyDeleteWasn't kidding about the planer gage, I will split my supply with you. It will serve better being used, then being in my toolbox.
Send email for contact details.
John in Philly
One factor about single phase motors on lathes is what seems to be a "hesitation" chatter. I'm told that the power pulses from a single phase motor can give the surface a wavy finish, as the cutting bit reacts to surface speed variations under cutting loads. IIRC, the effect shows up under various combinations of speed, feed, and material.
ReplyDeleteIt used to be that the variable speed vertical mills were more desirable, but with the advent of the VFD's (variable frequency) to convert single to 3 phase, and the resultant speed control it gave, the step belt setups became quite adequate, and easier to maintain. I think Hitachi was the big name in VFD's in the early 00's. No idea what the market is now.
There are lots of web pages detailing how to move the bigger iron.
I used a conventional tow truck to move a Bridgeport into a garage. It was dropped onto a trailer by forklift (forks under the sliding head rails with wood for cushions, with the head rotated down to the table for lower weight CG). (I've since heard that rotating the head down like that is not optimal, due to internal contamination from swarf.)
We then ran some heavy lifting straps from the same rails, and used the hydraulic boom to lift it, and then extended the boom to get it into the home garage. I used the stinger (wheel lift) to push it back farther, utilizing a bit of lumber. Moved a 700+ lb welding table with the same truck, essentially duplicating the action.