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Author Topic: 7x12 Mini-Lathe converted to CNC  (Read 11827 times)

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Offline Jfong

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7x12 Mini-Lathe converted to CNC
« on: May 20, 2014, 10:59:40 PM »
After converting a unimat lathe to cnc for my buddy, I decided that my own 7x12 mini lathe needs to be converted too. I had this short thk kr26 linear stage that I got for about $40 on eBay. To small for anything else but perfect for the lathe cross slide X axis. The carriage Z axis is a 10mm diameter THK ground ballscrew purchased from eBay for $115. Stepper motors are 300oz-in nema 23 that was given to me. Stepper drivers are Gecko210 also purchased used from eBay for cheap. Power supply is a diy 36 volt output from a transformer salvaged from a old broken desk lamp.

Backlash on both axis is minimal due to the high grade THK ground ballscrews. Rapid speed is set at 100ipm. I had tested it at 200ipm but thought that was ridiculously fast for such a small lathe.

Mach3 Turn running on a old P4 desktop using parallel port step/direction output.

In the video roughing pass is at 5ipm and the finished pass is 1ipm.

http://youtu.be/zuGZxvZJS_w

First time threading

http://youtu.be/2HpvWgHT8To



Re: 7x12 Mini-Lathe converted to CNC
« Reply #1 on: May 21, 2014, 11:30:47 AM »
Looks great & works great!  CNC lathes are such fun. ;D

Is that the stock spindle drive motor?  Speed control looks to be very stable.
Milton from Tennessee ya'll.

Offline Jfong

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7x12 Mini-Lathe converted to CNC
« Reply #2 on: May 21, 2014, 12:50:05 PM »
Thanks!
Ya it's the original stock motor and speed control.  I think having the larger 5" chuck helps to smooth it out, flywheel effect. 

The hardest part now is the CAM software. I haven't found any at a reasonable price yet so I am using the built in MACH wizards.

Offline Jfong

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7x12 Mini-Lathe converted to CNC
« Reply #3 on: May 21, 2014, 12:56:59 PM »
I made some tool holders for some TCMT inserts I got for cheap on eBay. They cut aluminum better than anything I've used before.
Re: 7x12 Mini-Lathe converted to CNC
« Reply #4 on: May 21, 2014, 01:10:56 PM »
The hardest part now is the CAM software. I haven't found any at a reasonable price yet so I am using the built in MACH wizards.
I got very lucky and bought Dolphin Lathe v10 for a great price from Hood here on the forum.  It has a few quirks but is a very powerful program.  Problem is that I use it so rarely I've never become proficient & struggle every time a need arises.  Most of my stuff is very simple & the Wizards work great.

Those are some great looking tool holders!
Milton from Tennessee ya'll.

Offline Jfong

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7x12 Mini-Lathe converted to CNC
« Reply #5 on: May 21, 2014, 01:55:29 PM »
I downloaded deskproto eval but I can't seem to get my head around lathe operations. It's not as simple as 3axis milling like cambam.   I'll keep using the wizards for now. 

I made a bunch of  those dovetail holders a few years ago. The one on the right is original that came with the tool post.   I figured it would be quicker to make some insert holders instead of ordering a set from LMS.

Offline Jfong

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7x12 Mini-Lathe converted to CNC
« Reply #6 on: May 23, 2014, 03:33:43 PM »
I did a simple turning last night. Small handle to replace a broken plastic one. Took about 15 minutes to do. Could never have done this manually or rather this nice looking while turning the lathe handles by hand. 
Re: 7x12 Mini-Lathe converted to CNC
« Reply #7 on: May 24, 2014, 11:13:21 AM »
Looks great!  What did you use for CAM?
Milton from Tennessee ya'll.

Offline Jfong

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7x12 Mini-Lathe converted to CNC
« Reply #8 on: May 24, 2014, 01:00:16 PM »
I downloaded the cambam eval and it has a beta lathe turning add on. For this simple part, it seems to work fine.  I haven't found any other inexpensive CAM program that can do lathe work yet.

Offline Jfong

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7x12 Mini-Lathe converted to CNC
« Reply #9 on: May 25, 2014, 12:20:37 AM »
Made a handle so I can put it on the rear of the stepper motor. Was cutting fine but near the end the X axis didn't retract enough and the tool bit hit the part.  Made from drill rod steel.  Have to reprogram and rerun the job.