PM-940m CNC - VS Motion Controller Conversion to Centroid Acorn

pburgh

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Originally, I was going to CNC a PM-940m with hardened ways from the ground up. When I started to gather the components for the build, I ran across the Centroid Acorn controller, and that was the first component I purchased. But during the course of starting the process, I decided to switch gears and purchase a turnkey machine instead and give that a try. Once I received the machine and checked out the nMotion controller with Mach 3, I decided to switch it out with the Acorn controller. One reason was that there is not a lot of information on the nMotion controller, and another is that I don’t have any experience with Mach 3. With all of the issues that I’ve read about Mach3, I decided to focus my efforts on switching to the Acorn controller and becoming familiar with the Centroid control software. This thread will document the process and I hope that others who have similar machines and want to change the controller/software will benefit from the information gathered here. Please feel free to share your knowledge and opinions during this process.
There is a wealth of information on the Centroid Acorn site page and Centroid’s Acorn forum. I will post the links below in the outline to get this started.

The general outline will be as follows:
  • Gather information on the Centroid Acorn setup
  • Compare and match the nMotion schematics to the Acorn schematics
    • Identify wiring matchups and changes needed. Determine what’s missing (5v power supply, momentary jog contact for limits)
    • Know that the wiring numbers may vary from machine to machine (thanks Jake)
    • This link to a post I created in the forum will fill in some of the info from questions that I had: http://centroidcncforum.com/viewtopic.php?f=60&t=1270
    • Document the changes needed for getting motion working on the machine with peer review
  • Focus on the Spindle/VFD setup
    • Formulate and verify the necessary changes through peer review
    • Test Spindle function
  • Look into adding flood coolant pump, lube pump, etc to outputs
I have already setup my computer and have bench tested the Acorn card according to the instruction videos. I followed Centroid’s recommendation on setting up an Intel NUC with Windows 10 Pro and I’m using a Viewsonic 24” touch screen monitor.
 
YES! Sub'ed and can't wait to see this thing in action!

I hope to be only a step or two behind you in this whole process! Building my new computer tonight!

PZ
 
Yup, right there with you both! I already have my computer setup and the 5v+24v power supply. Just waiting for the Acorn which should show up by the weekend. Cheers !
Jake
 
Great to hear guys! I'm pondering on how best to mount the new card in place of the nMotion card. I'd like to mount it perpendicular to the back board so i can leave space for a 4th axis drive if i go that direction. How are you all looking to mount yours?
Regards,
Doug
 
Hey All,
Here is a good video that I found on you tube giving an overview of using the Centroid software:

Enjoy!
Doug
 
Hey All,
Here is a good video that I found on you tube giving an overview of using the Centroid software:

Enjoy!
Doug

It is very good ! By coincidence I watched it this morning!
Good news, I have the Acorn moving all axis and also the spindle is spinning, and the e-stop working.
Initially I had not run the 24v jumper so the E stop was not functioning but would almost work but only upon restart of the program.
Unfortunately the E stop switch that comes with the PM940 does not mechanically function as Normally Closed. It has only two wiring terminals. The default wiring for the limit and home switches is also NO. I am not sure if they can be wired as NC as that’s preferable. Something to check.
The axis direction and axis STEP and DIR had to be inverted in the setup wizard, yours may not?! Also currently the spindle appears to be spinning the wrong direction but I need to verify that. There doesn’t appear to be a software fix. Likely two of the motor wires just need to be swapped on my 3 pole inverter motor.

More details to follow. The most pressing issue for me is to figure out why it persistently runs a default flange program when I hit the cycle start button. I have to quickly hit cycle stop which aborts the job, then I can jog around.

Anyway, good progress today, but hit a few snags, but nothing bad at all.

Jake
 
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HUGE note to avoid a crash while setting the software up or if you want test new hardware without it running a job. EVERY time you hit cycle start Centroid CNC software v12 will open the last job file you used. In my case it was "FLANGE. xxxx " something like that. It was probably loaded by the person that tested my card at the factory, or maybe its the default? Regardless, while you are troubleshooting the conversion to Acorn, you'll undoubtedly need or want to jog around to see if things are working you'll have to hit "cycle start ". What happens right away is it will load and start performing the last job / program you loaded. It will persist. This is a good function as it doesn't require you to find a file before continuing with the job you started the day before.

The solution is to create a "--NULL--" file that you load. It shouldn't have ANYTHING in it. Then you'll just load that file after you are done with a real "job/program" Thankfully someone posted that solution in October.

Note: I have not turned on "Home to Switch" yet, so this may change the behavior possibly?

Jake
 
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Good to know Jake, thanks for the heads up on all of this. That's fantastic that you've made this much progress. It's been unusually cold here in Florida, so I didn't work out in the garage as much as i'd liked to yesterday. I'm hoping to get more time today and i'll check out how my limits are wired for NO or NC. I didn't ring them out yet, but I'm going to have to get into each one to determine the colors they used for each wire on the common. Plus i'm still mulling around how I want to mount everything to take full advantage of the space.
Regards,
Doug
 
I started getting into the wiring on the 940 last night in preparation of the Acron showing up today. The limit switches can be wired NO or NC, there is an extra set of terminals inside the switch. On another note EVERY wire in my limit switches was loose, and one was even broken. No wonder my limits never worked right with M3... All better now!

Also, on my mill (ordered Jan 2016) there is a yellow wire that is not used in the step/dir cable going to the stepper drives. I Pulled that out for each axis and will use it as the enable. Also, the back plane in mine had holes for the drives to be moved to the right, I would assume to make room for the 4th axis. I went ahead and moved the drives over to create a little extra room for the Acorn. I'd post pics but it looks like the local squirrel population did a number on the phone line going into my house... So my interwebing is reduced to what I can do on breaks at work...

PZ
 
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