Help needed with PM-940m CNC VS conversion to the Acorn Controller

[rickwjenn]

Nice. And all running good?

Martyscncgarage - so far so good. Really like the straight forward acorn documents and software. The nmotion was, well, 3rd world.....

[pburgh]

That's interesting. I used Jake's diagram to eliminate the relays and it caused the Acorn board not to boot. I wonder if it's because I have the original version of the Acorn. Rickwjenn, did you make any programing changes to the VFD or did you just follow Jake's diagram?

Thanks
Doug

[Gary Campbell]

As posted numerous times, and especially with the early versions of Acorn, there are some known issues when external voltages are applied to the BBG prior to it booting. There are a number of posts explaining this and an equal or greater number of fixes. Including a simple one where those voltages are applied via an onboard relay set to OkFaultOut

[phazertwo]

PZ

cut2cut provided the direct wiring for Acorn to Delta VFD w/o relays at https://www.hobby-machinist.com/threads ... 196/page-2

I give him all the credit!

Wow... I have read through his thread a dozen time and can't remember seeing that...

PZ

[pburgh]

Yeah PZ, remember when I first set mine up I removed the relays and it killed the Acorn. Once I put them back everything was ok. I never looked into why that was happening. LOL, There are too many other hurdles with the 940 that keep me busy.... Once I replace everything, I should have a pretty good running machine.

[pburgh]

This is a question for Marty. I've used the spreadsheet you created to set the turns on all axis. It works very well. However, my Y axis is not calculating out right. I'm either over by a couple thou or under by half a thou. Any thoughts on why it would be inconsistent? I did change the count to 2000 from 1600 on the drives. Would it be that hard to tune? The X and Z worked well. And the backlash looks to be .0001. Thanks for any suggestions, comments.

Regards,
Doug

[martyscncgarage]

This is a question for Marty. I've used the spreadsheet you created to set the turns on all axis. It works very well. However, my Y axis is not calculating out right. I'm either over by a couple thou or under by half a thou. Any thoughts on why it would be inconsistent? I did change the count to 2000 from 1600 on the drives. Would it be that hard to tune? The X and Z worked well. And the backlash looks to be .0001. Thanks for any suggestions, comments.

Regards,
Doug

Pretty simple math.
Are you sure everything is mechanically tight? Check for backlash on Y axis?

[phazertwo]

Yeah PZ, remember when I first set mine up I removed the relays and it killed the Acorn. Once I put them back everything was ok. I never looked into why that was happening. LOL, There are too many other hurdles with the 940 that keep me busy.... Once I replace everything, I should have a pretty good running machine.

Yeah, it's coming back to me know. I could remember there was a good reason I didn't try it, but couldn't remember what it was....

I feel the same way about my 940 right now... too much other stuff going on to mess with stuff that is working.

PZ

[pburgh]

.
Pretty simple math.
Are you sure everything is mechanically tight? Check for backlash on Y axis?

I was able to dial it in when the count was 1600 and it was right on, but 2000 seems more touchy. Everything seems tight and the backlash is about .0001. I'm really scratching my head on this one. Plus, I'm not sure how good these Leadshine steppers are. Eventually I'd like to replace them with the DMM DYN4 setup. But I'm bleeding money into this thing and the big boss is starting to wonder what I'm doing.

Thanks,
Doug

[martyscncgarage]

Not a cheap hobby for sure!
Go back to 1600 and see if you can get it dead nuts.
Post your latest report.