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11-24-2005, 04:50 PM #1
In the current thread on CNC knee mills this comment was made:
"I wish there was a CNC lathe that was the equivilent of the 5k machining center while a little dated and slow and no tool changer was not beat to death.. That is something i might have a use for."
Buying a running and useable $5K or under CNC mill, or converting a manual mill, seems a moderately straightforward and common undertaking. CNC lathes appear to me to be a more complicated deal, but that could be due to my limited knowledge of them. I don't see much conversion/retrofit info on lathes compared to mills. Since only two axes are needed why isn't a lathe a third easier to convert than a mill?
Ready to go CNC lathes seem to jump from an Emco Compact type of trainer/desktop lathe (one of them was offered here in the Bay Area recently by someone in the model engine club) to a complicated/expensive to repair/maintain aged industrial lathe that may be beaten to death.
I briefly considered the Emco as it had very little use (this wasn't the slant bed version which is what I think Alan/wrench has) but for the price that was being asked it looked like a really small work envelope that might not be as useful as I'd hope for the price that was asked.
Setting aside the difficulties that Damon has had with his Hardinge retrofit [img]smile.gif[/img] what can the home shop/small shop person realistically get for that $5K investment? Let's presume that it is a pretty basic machine without a lot of whiz/bang tooling attachments that would be finicky to maintain. Something that would let a person add some swoopy inside/outside radii to a part, or make 4-5 identical parts if there was a need. I guess a spindle sensor would be needed for threading, and constant surface speed sounds like a nice feature but might be out of consideration in this price range.
It sounds like old CNC lathe controls may be more finicky than old CNC mill controls. I don't know if that is only the case in lathes with tool changers, powered tailstocks, parts catchers etc, or if it is true in general.
I'd think the usual advantages apply to a control conversion on an existing CNC lathe vs converting a manual machine - you've already got motors (and mounts), ball screws, hopefully the lathe is made beefier and to a higher quality for the heavier speeds and cuts, etc. But if you could get something with a working control you could maybe work with that until it has a fatal problem that would be uneconomic to fix.
Something in a minimum 10x24 size would seem to be needed to make it reasonably versatile.
So are used CNC lathes in this price range unlikely to be a realistic proposition? If so, what's the likely minimum range to be - $10K? I see that base price on a Haas TL-1 is $20K, but I presume that probably needs $5-10K in options before it would be really useable.
11-24-2005, 07:55 PM #2
I hear ya. Too bad there isn't something along the lines of a Tree Journeyman 325 in the lathe variety. Maybe there is but I havn't seen it. I ended up going with a BP Romi Centur35. Pretty basic machine with nice layout. Reasonable money but more then you are talking about.
11-24-2005, 10:37 PM #3
Build one, I did
Turbocnc (mach3 looks better now)
2 steppers, 2 ballscrews 2 gecko drives
1 "old" computer
1 lathe 11" x 33"
encoder for threading
lots of coffee and go to it.
11-24-2005, 11:38 PM #4
Inside of a year, I suspect MACH IV will be all anybody will ever need of want for milling OR turning. Hold your pants on for the control, menawhile look around for a lathe with ballscrews (EBAY, scrap yards, and local industry maintence departments included)....
Knowing some folks that work in larger machine shops and those that do field service on cnc machines, can
sometime get the scoop on a viable victim....er machine thats destined for the dumpster.....or just got freshly tossed into one....
And often the price is in "cents-per-pound" (my favorite pricing system on used machine tools)!
11-24-2005, 11:53 PM #5
*shudder* no problems with the HARDINGE side of the retofit
I was thinking about doing a EMC based retrofit on one, but the EMC project was not at all set up for a turning app and I didn't want to be stuck editing miles of code written by others while I had turning work backing up.
I have one hardinge out for a mach5 retrofit. I say mach 5 because the procedure is moving a bit slowly [img]smile.gif[/img]
Anyway lathes are pretty easy to retrofit. I think you would be better at either end of the spectrum. Fanuc or mach4. Since there is about a $10k cost differnce, lets focus on M4.
Simple interfacing for the fun stuff like tailstock feed, turret index, etc. It could be done without much trouble. In fact I bet the biggest obstacle would be getting the pinouts for all of the cables in the machine. Much easier if you get a machine that already has ballscrews and a turret.
On the relatively simple hardinge, I believe there were near 150 wires to connect up. If you have to rip the machine apart to ohm out limit switches, solenoids, encoders, it will take you decades.
I haven't looked at the Mach4 setup for threading, but for arcs, tapers, etc - it is a walk in the park.
Dan - I should have been holding onto my pants when I ordered the retrofit :rolleyes:
11-25-2005, 12:06 AM #6Dan - I should have been holding onto my pants when I ordered the retrofit [Roll Eyes]
Centroid & Ajax cnc....SUCKS!!
11-25-2005, 05:51 AM #7
The first thing in retrofitting an old CNC is to simplify... they are often excessively complex. Stripping it down to bare metal (i.e., no electronics on it at all) might not be unreasonable. Then, you can add your own PC based system, with simple, straightforward controls to it, without dealing with the mass-quantity of excessive logic and wiring that the old system had (as much of that old hardware-based logic is now done in software on the PC).
Parts could include:
2 to 4 Geckos (the third for the tool-changer turret, made from a small rotary table with a servo on it; the fourth for a powered tail-stock - both optional features)
Home/Limit switches (theoretically optional, but I wouldn't do one without em'). Also included in this category is the door switch.
One thing I would keep from the previous setup, if equipped, would be the hydraulic chuck/collet closer and solenoid valves - I'd hook em' up to a parallel-port relay card (like, say, one from CNC4PC).
So, a bare-bones system might get by with only about 20 separate wires to hookup to the machine, plus the Gecko-to-pc harness and power supply...
11-25-2005, 01:15 PM #8
When I was out looking for used machines several years ago I found myself in the 15-25k range. I did find some less expensive machines but after seeing what the next range up offered I decided less expensive was not the way to go.
Machines under 15k where either stripped versions or clapped out. Older models did not have the options and cycles to facilate easy programming and downloading. Parts and service was not quite up to snuff either. Some repairs and parts on older machines can cost more then the machine is worth. Something to keep in mind.
For me I needed a machine I could learn easily AKA "User Friendly" a machine that would be reliable and parts and service would be available. I needed to learn how to machine parts with a CNC, not learn how to build and repair a CNC that could be used to make parts too.
11-25-2005, 02:51 PM #9I needed to learn how to machine parts with a CNC, not learn how to build and repair a CNC that could be used to make parts too.
Keeps me out of the bars............