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PM-940m CNC - VS Motion Controller Conversion to Centroid Acorn
- Thread starter pburgh
- Start date
Spent most of yesterday working on the mill. It was bugging me that I was only getting 40 ipm out of the Z, even though the spec on the quote from PM was 75ipm. So I started digging into it and the X,Y,Z drives were all set identically, even thought he Z is a 1200 oz-in and the X and Y are 640 oz-in. Looks like the Z can run 1 row higher on the amperage table (according to the specs from Leadshines website), so I configured the dip switches accordingly and started testing. I was able to get 75 ipm with out missing steps (just jogging around) however it sounded like hell, which made me remember a post from Jake about removing the manual Z. I decided there is no time like the present and I pulled the electrical panel off the column and removed the pinion from the manual Z and did some more testing. WHOOLY SMOOTH! The Z has always been noisy and clunky, now it's smooth as butter and running 75 ipm!
Made this test part as another validation. Everything is ±0.002, with most operations in the y being ±0.001 so I might need to re-tune the X. Tried to use more tools that I haven't used with the Acorn yet, so I used the Super Fly to bring the top down (though I didn't come down far enough, as shown by the tool marks down the center from the original scrap part), roughing end mill to hog everything out aggressively, drilled a hole down the center, and used the chamfer tool to deburr. Everything ran flawlessly.
LOVING the Acorn. I'm ready to make my first useful part, which will be a cover plate to replace the bearing cover for the manual Z.
PZ
Made this test part as another validation. Everything is ±0.002, with most operations in the y being ±0.001 so I might need to re-tune the X. Tried to use more tools that I haven't used with the Acorn yet, so I used the Super Fly to bring the top down (though I didn't come down far enough, as shown by the tool marks down the center from the original scrap part), roughing end mill to hog everything out aggressively, drilled a hole down the center, and used the chamfer tool to deburr. Everything ran flawlessly.
LOVING the Acorn. I'm ready to make my first useful part, which will be a cover plate to replace the bearing cover for the manual Z.
PZ
Thats awesome PZ, the part looks great. Yeah, I'm really liking the Acorn too. My Z is still a bit noisy but hugely better than when I had the manual crank connected. I intend to dig into it, but my Z ball screw seems to be miss-aligned or bent. Someday I'll get into that but until then, I have other projects, like rigid tapping.
Not sure you guys saw Marty's video on the cheap Omron encoder. It works ok so far and its only $25. The supplied coupler is just barely adequate and will probably result in failed encoder bearings. It can handle 5000 rpm max so it should be adequate for most jobs. Currently I've rigged mine up so I can see if I can do rigid tapping. Too early to say if I have my VFD setup properly as I need some proper sized bits for my test tap. I'll report my results. Likely I'll use a hybrid most of the time, with a compression/tension tap head and the encoder to give the tension head the least amount of "work" possible, so it won't be truly rigid tapping but only because it should produce the results I want.
If you can sometime, please share a picture of the dip switch settings for the Z drive. I'd like to push mine a bit more so it won't loose steps as easily.
Cheers,
Jake
Not sure you guys saw Marty's video on the cheap Omron encoder. It works ok so far and its only $25. The supplied coupler is just barely adequate and will probably result in failed encoder bearings. It can handle 5000 rpm max so it should be adequate for most jobs. Currently I've rigged mine up so I can see if I can do rigid tapping. Too early to say if I have my VFD setup properly as I need some proper sized bits for my test tap. I'll report my results. Likely I'll use a hybrid most of the time, with a compression/tension tap head and the encoder to give the tension head the least amount of "work" possible, so it won't be truly rigid tapping but only because it should produce the results I want.
If you can sometime, please share a picture of the dip switch settings for the Z drive. I'd like to push mine a bit more so it won't loose steps as easily.
Cheers,
Jake
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Looks like we are near each other ! I live in Seattle.
Mine has been randomly not firing up as well. I'll have to make note of that when I fire up the computer the next time !
Jake
Yes, I am over in Port Townsend, just moved from Sammamish. Andy
Sorry it took so long, but here are my current settings for the Z and Y axis. X is set identical to the Y.
I did have a strange situation where I missed steps on Sunday, not sure what caused it but the Y just didn't go. It really messed up the part, which was a huge bummer, so I backed off on the speed and acceleration.
My current settings:
X & Y set to 100IPM and 0.3s accel
Z set to 60 IPM and 0.3s accel
I feel like these are a touch conservative, but after messing that part up I decided it's better to move a bit slower and get it done right.
PZ
I did have a strange situation where I missed steps on Sunday, not sure what caused it but the Y just didn't go. It really messed up the part, which was a huge bummer, so I backed off on the speed and acceleration.
My current settings:
X & Y set to 100IPM and 0.3s accel
Z set to 60 IPM and 0.3s accel
I feel like these are a touch conservative, but after messing that part up I decided it's better to move a bit slower and get it done right.
PZ
Holy cow Batman. 100ipn. Assuming that’s just rapids . What Speed are you cutting at usually ?
Yeah, 100 IPM is max speed. I seem to spend a lot of time between 15 and 25IPM cutting, but it all depends, I have hit 39IPM roughing aluminum.
I've just been running everything at full spindle speed and then setting the IPT to 0.001 or 0.002 depending on roughing or finishing. I got this set of carbide end mills and they have been awesome. I used the 6mm to do 8 0.825" holes in a 0.5" steel part, and it's still in great shape.
https://www.amazon.com/gp/product/B01M0W9XON/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
And I have been using this to rough out aluminum.
https://www.amazon.com/gp/product/B01AOE7DBU/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
That rougher loves to plow through aluminum, I have really been pushing it to see what it can do and I honestly can't believe it still in as good of shape as it is. I have had to use a small punch and hammer to clear aluminum from it more than once, but it still looks sharp and cuts like new.
I'm working on a S&F spread sheet I'll share once I get it a little more nailed down. I'm going to include links to all of the tools I bought online (mostly amazon).
PZ
I've just been running everything at full spindle speed and then setting the IPT to 0.001 or 0.002 depending on roughing or finishing. I got this set of carbide end mills and they have been awesome. I used the 6mm to do 8 0.825" holes in a 0.5" steel part, and it's still in great shape.
https://www.amazon.com/gp/product/B01M0W9XON/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
And I have been using this to rough out aluminum.
https://www.amazon.com/gp/product/B01AOE7DBU/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
That rougher loves to plow through aluminum, I have really been pushing it to see what it can do and I honestly can't believe it still in as good of shape as it is. I have had to use a small punch and hammer to clear aluminum from it more than once, but it still looks sharp and cuts like new.
I'm working on a S&F spread sheet I'll share once I get it a little more nailed down. I'm going to include links to all of the tools I bought online (mostly amazon).
PZ
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