Shop Fox M1098

'Been looking for a small lathe I can quickly upgrade to CNC.
Among them is the Shop Fox 13x40 M1098. A hands-on look makes it seem like
a pretty well-made machine for an off-shore rig.
Anybody here have any experience with them?
LLoyd
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On Mon, 16 May 2011 06:18:32 -0500, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:>'Been looking for a small lathe I can quickly upgrade to CNC.

Have you looked at buying a dead CNC lathe? It does take searching but you'll be way closer to your goal. I'm partial to Hardinge because so dang many were made twenty years ago.
That said, looks like a decent enough import lathe. I'd have a design concept in mind for your ball screws and stepper/servos before you buy.
Karl
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I have looked, Karl, but two things stop me. Most of the used CNC machines I'd have access to (say, in a 200 mile circle of me) are darned-well USED, and not in stellar condition.
Also, I cannot do the tax re-capture single-year amortization of a used machine. Buying new gets me an ROI of about 16 months.
The guys at Mach Motion have already done a nice conversion of exactly the same model lathe of a different badge. I'm not overly impressed with the Mach3 control, which apparently has trouble doing threading unless you buy the (additional) MachMotion $2550 stand-alone motion controller that goes between Mach3 and the drivers.
I'm pretty certain that Iggy has proven EMC will do it without all that additional computing power and unsupportable embedded proprietary code.
However, since they've converted a lathe that is mechanically identical to the Shop Fox, I assume it's not to ugly mechanically -- and heck! I'll have the lathe working in manual mode to do the work <G>.
LLoyd
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On Mon, 16 May 2011 07:28:14 -0500, "Lloyd E. Sponenburgh"

How about starting with a Lancer lathe? i see a fella here offering a project lathe cheap. And you wouldn't have to take it apart first <VBG> I bet he'd find you some ball screws and servo motors to sweeten the deal.
Seriously, that would make one hell of a lathe.
Karl
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I've got a better accountant than you. No problem to section 179 used equipment and expense it.
Karl
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Lloyd, my opinion is worth $0.01, but I feel that I have to state it.
CNC retrofit of a machine that is built as a CNC machine, is a COMPLETELY different type of project than a CNC retrofit of a manual machine.
If the difficulty of the former is 6 on the scale of 1-10, then the latter is 9-10.
You have to be essentially a CNC machine designer, make a lot of things fit that do not want to fit, make and mount a lot of brackets, doodads, switches. Also you need to buy servo motors.
It all seems simple conceptually, until a) you start doing it and b) make some mistakes that you realize late in the game. For sure it is NOT cheap, if you price your time at $5 per hour and up.
I agree that a CNC lathe that is not totally clapped out, is harder to find that a mill or a VMC.
I may be overstating my case or just not experienced enough to breeze through that sort of thing. But somehow, I feel that retrofitting manuals machines is not nearly as cost effective as taking a CNC machine with a bad control.
i
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Ig, I take your advice seriously, but I have the advantage that they have already converted one of these. Only two small issues must be resolved on my end:
I must make a ball nut bracket for each of the Z and Y feeds, and I must add thrust bearings to the ends of the screw brackets to take out end play. They have motor mounts and couplers designed to purpose, and the adaptor plates and couplers only add about $50 to the total bill -- saving me much layout and machining time.
I have pretty much exhausted the near-regional used CNC lathe market looking for anything that doesn't have so much wear as to require a full screw and motor upgrade (and way scraping), and I think I'd rather do the conversion. I intend not to kill the manual functions until everything is ready (although I'll probably do several disassemblies and re- assemblies of everything before I'm done).
Things like mounting limit switches are just not that much of a challenge.
As for mistakes? Yeah... but they're all "recoverable", so long as I don't invest in motors or ball screw assemblies that are sub-standard. To that end, I'll be using some proven motors, and precision-ground screw/nut combinations. The precision of rolled screws just leaves me cold -- 0.003" per foot is crazy sloppy.
LLoyd
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On 2011-05-16, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

Keep us posted Lloyd, I do not want to discourage you in any way.
i
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in

In any case, this will be pretty rapid-fire, except, perhaps, for the budget. The motors and drivers will cost me $1200 for new, proven AC- Brushless Servos and 2500 line encoders. That's the biggest rub. The screws are pricey anywhere you get them, when you go to the 0.0005"/ft. versions.
I'll be working hard to preserve all of the manual features except for threading (I have a 6x18 that can do for the time being), until that very last moment when I "switch over".
LLoyd
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"Lloyd E. Sponenburgh" wrote:

I've only seen two used lathes in my area in two years, and you wouldn't have wanted either of them. At least one was scrapped because it needed so much work.
--
You can't fix stupid. You can't even put a Band-Aid on it, because it's
Teflon coated.
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Lloyd E. Sponenburgh wrote:

The option is to use glass scales with a rolled screw. AS long as the ball screw has no backlash the glass scale will give accurate position with no backlash.
John
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"Lloyd E. Sponenburgh" wrote:

Don't forget that CNC controls include screw mapping / pitch error compensation. Measure and map the screw once and all the inaccuracy is gone for good, or at least until you wear out the screw. Commercial machines / controls use screw mapping as well.
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Yes, true enough, but the one thing I don't have is the gear to measure that over 30-some inches of carriage travel. On the one hand, the hardware would be cheaper, on the gripping hand (using precision screws), I wouldn't need the instruments (I can live with a thou. over three feet). Maybe I could get someone who does have the tools to come do the mapping...
LLoyd
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"Lloyd E. Sponenburgh" wrote:

Most people use a dial indicator and map the screw an inch at a time.
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Not hardly, Pete. I've watched that procedure before on big VMCs. You want not only "localized" errors, but cumulative errors to be mapped.
As Ed stated below, the Japanese techs were using laser devices. The could map a 6' travel to half a tenth, cumulative, easily. (I'm betting it was better than that)
LLoyd
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"Lloyd E. Sponenburgh" wrote:

My reference was to people doing CNC retrofits, not big commercial machines. Whe we replaced ball screws on the big machines the new ball screws came with a pitch error table to enter into the control.
Also, measuring an inch at a time does not "localize" errors, you map continuously from one end to the other and unless you are quite sloppy, you introduce no cumulative error into that mapping.

Yep, the ball screws for real machines are laser mapped. You can probably buy your ball screws mapped with a pitch error table included for an extra charge.
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Gunner Asch wrote:

I would expect that with the drive for higher and higher accuracy on the high end stuff, that would trickle down to the lower end stuff as well.
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

There are calibration service companies that will do the job with laser interferometers. There are home-made solutions, but they're very tedious and slow. And I forget what they are. d8-)
--
Ed Huntress



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On Tue, 17 May 2011 10:09:27 -0500, "Lloyd E. Sponenburgh"

Hmm, that's right. You'd need some sort of feedback (DRO?) to do the mapping, wooncha?
-- It could probably be shown by facts and figures that there is no distinctively native American criminal class except Congress. -- Mark Twain
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Yeah, and the new lathe doesn't come with a DRO, which would run me roughly $700. I'll bet I can wheedle someone qualified to do it for half that.
The question, then, is would precision, pre-machined-ends screws cost me in differential cost even less than that. I'm betting yes, but haven't nailed it down. The precision-ground screw crowd doesn't seem to list their prices on-line (which could be BADDD!<G>)
LLoyd
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