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CNC Large Lathe Conversion pictures
« on: December 27, 2010, 09:54:46 PM »
Hello everyone!
Here are some pictures of a lathe we use to turn railway wheels that I converted to CNC using Mach3.  So far, the servos, drive and control are installed and work very well.  I've done a few tests with Mach3 and everything has blown away my expectations.  I also found out the hard way why one should install the limit switches before you go playing and testing stuff... This week I am going to start putting the electronics in their proper enclosures and knocking out all the details necessary to get it working (ball screw covers etc.)

Specs---
Year: ???
Max turning diameter to ways: 60"
Max length between centers: 8 Feet
Spindle HP: 25
Spindle R.P.M.: Approx 20 (Low Gear) and 160 (High Gear)

I'd be happy to answer any questions about the setup.

Enjoy!

Frank















And this is what happens when you start playing with stuff before you install the limit switches.  Luckily, the ballscrew sprung right back to shape with 0 runout, I did have to re-do the mounts for the servo and gearbox.  ;D



Re: CNC Large Lathe Conversion pictures
« Reply #1 on: December 27, 2010, 11:39:13 PM »
That is really awesome to see Frank!

Thanks for the great photos and explination of what it's used for. Very interesting.  :)

Kerry Harrison

Offline Sam

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Re: CNC Large Lathe Conversion pictures
« Reply #2 on: December 28, 2010, 03:16:21 AM »
Wow, now aint that somethin! The original purchaser would likely be amazed at an electric motor hooked to it for power, much less a machine that makes cuts all on its own. Thanks for sharing it with us!
"CONFIDENCE: it's the feeling you experience before you fully understand the situation."

Offline Tweakie.CNC

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Re: CNC Large Lathe Conversion pictures
« Reply #3 on: December 28, 2010, 04:17:39 AM »
That is some machine.
Thanks for sharing the pictures with us Frank - please update this thread with your future progress.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Hood

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Re: CNC Large Lathe Conversion pictures
« Reply #4 on: December 28, 2010, 09:49:48 AM »
Looks great :)
What size servos are they and is that a gearbox between servos and pulley?

On a side note I have never understood why old lathes (American especially) have such small wings on the saddle compared to the centre height, I would imagine it would make it difficult to take a decent cut without chatter.

Hood
Re: CNC Large Lathe Conversion pictures
« Reply #5 on: December 28, 2010, 01:15:42 PM »
Thanks!
I believe the machine is from the early 1940's, it didn't have a motor when we recieved it, but I am pretty sure it was electric.  The machine came to us from a shipyard (the original owner) and was exclusively used for straightening prop shafts and had been replaced by another machine many years before.  Other than a little clean-up it was ready ready for use... its amazing how excellent old fabrication is.  

The servos are Panasonic 750W (1 H.P.) 3P 230V units with matching drivers.  I am using Parker 50:1 gear boxes on both axis.  Because most of the cuts on this machine are slow (20 R.P.M. low gear and about 164 on high gear) and deep (we regularly did 15mm cuts manually before the conversion), we decided to add the 50:1 gearboxes to increase the feed torque at the low feed rates required (approx. 15mm/min low gear and up to 40mm/min in high gear).  So far it looks like that was a good idea, the only draw back is that my max shuttle speed is roughly 25 cm/min on X and 50 cm/min on Z.  But even at that speeds its WORLDS better than the 5 minutes it would take to shuttle the saddle BY-HAND from one end to the other!  ;D

The ballscrews are .75" diam/5mm pitch on X and 2.5" diam/10mm pitch on Y.

The timing belt and pulleys were a last minute thing, my father was concerned that having the X axis servo and gear box straight out from the saddle would risk it being ripped out by a careless forklift operator, falling part etc.

Hood, you are certainly right about the chatter being a pain, but its not from the saddle flexing, its from the play on the ways when the X axis out past the Z ways, the way guides need to be very well adjusted for play.  It doesn't happen very often, but when you start to see chatter (see pic) its almost always because the X or Z way guide needs to be tightened.  We also fabbed the tool post and holder ourselves because the original one wasn't sturdy enough for the wheels (another thing that caused chatter).  I'll post a pic of the original tool post in the afternoon.

Frank

« Last Edit: December 28, 2010, 01:18:49 PM by zonian1903 »

Offline Hood

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Re: CNC Large Lathe Conversion pictures
« Reply #6 on: December 28, 2010, 02:43:56 PM »
Sounds like you should have plenty torque there :) 50:1  will be giving you 100 or so Nm I would imagine.

Hood
Re: CNC Large Lathe Conversion pictures
« Reply #7 on: December 28, 2010, 06:12:08 PM »
I'm sure Sam(moderator) reply only because you have include a picture with a bottle of WD-40 ;D ;D

Could not resist.


I love this picture

Jeff ;)

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Re: CNC Large Lathe Conversion pictures
« Reply #8 on: December 28, 2010, 07:27:46 PM »
Darn right. We hillbillies use the stuff as cologne, before a night out on the town.
"CONFIDENCE: it's the feeling you experience before you fully understand the situation."

Offline poppabear

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Re: CNC Large Lathe Conversion pictures
« Reply #9 on: December 29, 2010, 03:41:34 AM »
Sam,

   Did you say, "Hill Billie"?  If so "wer u from", I am just a little north of "Knox-vagus" (knoxville, tn).

scott
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/