Stepper motors-lathe

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07 Jun 2011 23:11 #10365 by occesar_0
I need to automate an 1967 lathe. In my latest project, I was working with servo motors, but this time I need to work with stepper motors because of its low prices. So i was studying a little bit of stepper motors and I found out that there's some parameteres or rules called NEMA.

Well, surfing on the net I realized that people who has been working in a lathe project, recomends an stepper motor NEMA 23,but they don't say why. I'm convinced that it depends of the equipment requirements but, can you let me know about your experience?

I mean what else do I need to know about?
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07 Jun 2011 23:39 #10366 by BigJohnT
Replied by BigJohnT on topic Re:Stepper motors-lathe
Well there is a lot to consider when choosing drive motors for CNC machines...

wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Mechanical_Spreadsheet

wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Stepper_Formulas

and other pages on the wiki and other places.

I can pretty much guarantee a NEMA 23 stepper will not move that much iron and if it does the gearing would be so high you would need a chalk mark on the wall to see it move. There are many problems converting a manual machine to CNC... leadscrews need to be replaced with ballscrews is the biggest headache in converting. Then selecting the correct motor to drive them etc. I'm not saying it can't be done but it is a lot of research and work to do so. I actually have plans in my head for adding a small CNC XZ table to my lathe of similar size for threading mostly. But that is down the road a ways.

John

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08 Jun 2011 06:17 #10368 by occesar_0
Replied by occesar_0 on topic Re:Stepper motors-lathe
Thanks a lot,

so I'll be thinking about a NEMA 34. There's so much work to do, I'll be posting my advances and I hope you can carry out your project without problems.

C├ęsar

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11 Jun 2011 22:16 #10432 by andypugh
Replied by andypugh on topic Re:Stepper motors-lathe
Nice lathe.

Even NEMA 34 might struggle with that. If I was you I would be stalking eBay for cheap / mis-advertised servo motors.

You might be able to keep the leadscrews if you write the G-code to always back out before in, like you do with a manual machine. However, you would need to use the leadscrew full-time, rather then the power-feed shaft and transmission, to I think that a ballscrew conversion might be needed for longevity.

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