# PM-940 CNC VS Converted to Acorn



## Rickwjenn (Jul 29, 2018)

First thanks to pburgh, cut2cut, phazertwo - all the info you guys shared was very valuable as I read and re-read then went to work...

Got my PM-940CNC VS a few weeks ago.   Spent one day looking the nMotion controller and the terrible documentation and ordered the Acorn.

Rewired all the home and limit switches to be NC and got a new NC E-Stop Switch.

"Bench" tested with the Acorn on the bench and jumpers running to the Stepper Drives as first step. 

Then mounted Meanwell RD-RD35B where the nMotion was and used 10-32 threaded rod to build a stand off mount for the Acorn.

Getting the spindle motor running took the most time and I eventually pulled the relays and when direct from Acorn to the Delta VFD - that did the trick and out came the relays and their wiring...

Bought Fusion360 and am going to start making some simple parts for my muscle cars and my dads '58 chevy truck.  With the mill and my Miller MIG, Miller TIG, and all my handtools I feel like I can fab just about anything.   Sheet metal brake and sheer is next tool!

Here come the pictures....


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## Rickwjenn (Jul 29, 2018)

Here is the Acorn in it is new home


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## Rickwjenn (Jul 29, 2018)

Here is Delta VFD wiring - note open area were relays WERE


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## Rickwjenn (Jul 29, 2018)

Here is what came OUT - NMotion, Relays, Wiring, NO E-Stop Switch


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## Rickwjenn (Jul 29, 2018)

PM-940 CNC all done and ready for me to try some simple parts...


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## Rickwjenn (Jul 29, 2018)

One of the cars I am going to make simple brackets, linkage, etc. for - 1967 Camaro 396 4 speed.  I have two engines - the original number matching one that is mildly modified and another big block for all out hot rodding.  Two trans as well - the original M-22 and a Jerico that  can be punished.  I can get the engine and trans out of the camaro in about 45 minutes as most work is simply easier with the powertrain OUT.   Loves these old cars - 7/16, 1/2, 9/16, and 5/8 inch tools get 90% of the fasteners and one 12v hot line + gas and it starts and runs!


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## 7milesup (Jul 29, 2018)

Awesome!   That looks like a great project.  I have an 833T mill that I have been thinking about doing a CNC convert on.

Is that a Ferrari in the foreground?


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## Rickwjenn (Jul 29, 2018)

7milesup - are you pilot?  Very cool.

The 833T is a great mill and I was going to get it but it was back ordered. Then the deal on a PM-940 CNC was offered on a unit in stock.   I bought it the next day!


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## 7milesup (Jul 29, 2018)

Yes, I am a pilot.  My avatar is the type of aircraft I flew the longest which was about 14 years or so.  It is a Hawker 800XP.   Lovely flying aircraft.  I retired early due to a medical condition, so now I play with metal working, radio control aircraft, and whatever else piques my interest  
Just found out while attending the Oshkosh airshow this past week that I might be able to get back into flying just for fun.  WOOT!


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## Rickwjenn (Jul 30, 2018)

7milesup - nice!  It has to be a lifetime experience to be the Oshkosh airshow!  Maybe you be in the air again soon sir.


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## phazertwo (Jul 31, 2018)

Just read through this on the Acron board.  Good stuff.  Glad that the other 940-Acorn guys and I were able to help.

How did you wire the VFD with out the relays.  I seem to remember that I needed them...  I would love to use them for other stuff though!

Thanks,


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## Rickwjenn (Aug 5, 2018)

Phazer - I believe you picked this up on the centroid board as well:

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!


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## phazertwo (Aug 5, 2018)

I did, thanks.

PZ


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## Rickwjenn (Aug 20, 2018)

Continuing to make some good progress.  While I am learning Fusion 360, I am writing more G Code programs to get the feel of the machine and creating tool paths.   Got the head lined up better with the table - it was sagging  .

Was pretty impressed (for a newbie) after aligning the vise fixed face to be parallel with the x axis:






Next I did a practice run for a power steering actuator bracket for my dad's 58 Chevy truck street rod.   Pretty simple clamp to go around 2.5 inch cylinder.  I wrote a simple G code program to cut the 180 degree arc with offset for a 0.5" end mill.   Played around with cutting as little as 0.01" in depth per pass to 0.1".    Once I make the part in Fusion 360, I will use this learning to see how many passes to make.    Going to make one out of mild steel as well.


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## pburgh (Sep 5, 2018)

Hey Rick,
Glad to see things are coming along for you.  And, I see you got the  remote. That makes things very convenient.  Are you still running the steppers at the original setup of 1600?  If you saw Keith's post, he recommends at least 2000.  I had to set mine to 3200 because I couldn't get the Y axis to dial in consistently at 2000.  The other 2, no issue.   I know that sounds weird, but it happened like that.  It runs smoother at 3200, and I don't know that it lost enough torque to make it an issue.  And I don't see any struggle with the Z going up.

Take care,
Doug


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## Rickwjenn (Sep 5, 2018)

Doug - thanks.  No on my first runs the actual distance traveled was off from machine steps/machine measurements.   Knew something was wrong.   The motors were on 2000 steps / rev from the Leadshine profile.   I looked up that settings should 3200 and it works great.  I put 3200 steps / rev on all axis and so not an issue.  I did this part from Fusion 360 all the way to the milling and it out exactly on the geometry to at least 0.002".  I didn't try to measure any more accurately.


My Z axis flies up and and down with the only issue it will creep down on power down unless I set drag on the head with the locking screws.


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## TomS (Sep 5, 2018)

Rickwjenn said:


> Doug - thanks.  No on my first runs the actual distance traveled was off from machine steps/machine measurements.   Knew something was wrong.   The motors were on 2000 steps / rev from the Leadshine profile.   I looked up that settings should 3200 and it works great.  I put 3200 steps / rev on all axis and so not an issue.  I did this part from Fusion 360 all the way to the milling and it out exactly on the geometry to at least 0.002".  I didn't try to measure any more accurately.
> 
> 
> My Z axis flies up and and down with the only issue it will creep down on power down unless I set drag on the head with the locking screws.



Nice work!  I read the thread about increasing steps to 3200.  My X and Y were set at 1000.  After changing to 3200 steps and adjusting steps/per I saw a significant change for the better in surface finish, especially on radius and angle cuts.  Thanks to Keith for the heads-up.


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## pburgh (Sep 5, 2018)

Guys, 
Good to hear.  If you haven't seen Marty's video on you tube  



  for tuning the motors, you have to check it out.  He gives a convenient spreadsheet too you can use to make the calcs.  I was too lazy to make my own spreadsheet.   Marty's the best!

Regards,
Doug


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## Rickwjenn (Sep 6, 2018)

Thanks for the link - will check it out!


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