A Motor and encoder to use with a Sherline lathe for ridged tapping

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ChrisMe
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A Motor and encoder to use with a Sherline lathe for ridged tapping

Post by ChrisMe »

I'm looking to "build" a CNC lathe system to mainly make mainly mine screws. I was going to buy a Sherline Ball Screw Chucker lathe however the Sherline motor is not capable of reversing (and I don't think their software is capable or ridged tapping) so I was going to run it on Acorn however this is still leaving me with the hardware problem of "I need a motor that is compatible with the Sherline lathe and Acorn" and as the motor will drive the spindle with a pully -as supposed to directly- I also need an encoder to accurately drive the spindle. For example advance the tap 12 thou for every spindle rotation.

I'm also in the UK to confuse things more. If anyone could recommend a motor and encoder that would be great. Thanks for the help.
Nigelo
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Re: A Motor and encoder to use with a Sherline lathe for ridged tapping

Post by Nigelo »

Chris

It doesn't matter how the motor drives the spindle. You will need to provide an encoder compatible with Acorn that is driven by the spindle not the motor (e.g. with Toothed timing belt) at a strict 1:1 ratio for rigid tapping.

Another issue I can see is that the Sherline chuck appears to be attached to the spindle by screw thread, similar to Myfords, which is not recommended for reversing as it could unscrew itself although that might not be an issue for your intended use.

Finally, the motor ideally needs to be AC driven by a VFD. It is the driver (ie VFD) not the motor that needs compatibility with Acorn which accepts 0-5vdc and PWM as well as the more common 0-10vdc. I believe a DC motor can be controlled in a similar way but search the forum for more info on this.

See also the technical bulletin https://www.centroidcnc.com/dealersuppo ... ds/304.pdf

Also don't worry about being in the UK, there are several of us on here :mrgreen: and Centroid's delivery to the UK is excellent, sometimes within 48 hours

Hope this helps
Nigel
ChrisMe
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Re: A Motor and encoder to use with a Sherline lathe for ridged tapping

Post by ChrisMe »

Thank you for the reply. This is making more sense now. Wire the control board to the VFD and wire the VFD to the motor.

How do I know if the VFD is compatible with Acorn? Will any 10VDC VFD work?

And will that also be able to reverse the motor on it's own? Can I sent the software to stop the current for a set time so the motor has time to stop before reversing the current?

Thanks.
Nigelo
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CNC Control System Serial Number: F045DA80C8B8-0905181172
E415F6F70BC3-0318203049
Location: UK

Re: A Motor and encoder to use with a Sherline lathe for ridged tapping

Post by Nigelo »

Yes, but remember the VFD has to be compatible with the AC motor.

Pretty much all VFDs supporting 0-10vdc will work with Acorn but to be sure before you buy, post the Make and Model here not forgetting to upload the VFD specs or at least a link to same. I am not a fan of Chinese equipment although some on here use the genuine non-cloned items to good effect. I use Schneider's Altivar range.

The VFD should have inputs for Fwd, Rev and speed control all of which will need to be connected to Acorn and configured accordingly. Upon receiving an M3 command in your G code the Acorn software can then activate a SpinFwd command on the appropriate Output (wired to the VFD Forward input). Similarly, an M4 command in your G code activates a SpinRev command on the appropriate output. An M5 command in your G code stops either of course by deactivating your M3/M4. If you need a pause between FWD and REV this should be provided in your G code equal to your Decel setting in Acorn which should also match your VFD settings.

Start off the right way and study Keith's straight forward guides (including the links they contain) as follows:

viewtopic.php?f=60&t=3397

viewtopic.php?f=60&t=5313
martyscncgarage
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Location: Mesa, AZ

Re: A Motor and encoder to use with a Sherline lathe for ridged tapping

Post by martyscncgarage »

Consider a motor from TVT America. 3 phase small motors. Use a Sensorless vector VFD with them
https://www.tvtamerica.net/collections/mt%C2%AE
Since they are made in Italy, I would imagine you could find a dealer near you.

What kind of spindle motor is on the machine now? Picture/nameplate?
Is it variable speed? Picture/model of the controller? Give us the BIG picture
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
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