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

phazertwo said:
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
Click to expand...

Thanks for the end mill suggestions and also the stepper drive settings. , I’ll give them all a try. Looks like you are enjoying yourself!

Was busy yesterday evening wiring up the VFD I’ve had sitting around collecting dust. It has a feedback card to take advantage of the spindle motors encoder to maintain better torque and rpm. Also implementing a brake resistor. It’s all to be able to rigid tap. Fast acceleration and deceleration are required. It’s just one of those goals, I gotta be able to tap easily and consistently , even if it’s with a compression / tension tapping head, I need it ! Lol I really should be focusing on the power draw bar though, but almost everything needs threads, right ! Lol. I should order up that cylinder Doug suggested. I just don’t really want to have a compressor running all the time. Noise.... lol. Going to have to build a sound proof box for it, I guess ! Totally worth it though , to have a power draw bar.

Jake


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I hear you on the rigid taping, it would be super nice. I'm going to attempt some thread milling, the tooling is expensive, and its a much slower operation (at least with single point) but I mostly am going to need 3/8-16 and 1/4-20 threads, and If I get the two tread mills that can do that I think I'm out ~$140. With those two mills I should be able to do anything with a 14-56 TPI thread, assuming it will fit in the ID. For everything 1/2" to 7/8" I will have to do UNF instead of UNC, but I can live with that.

I'm thinking now that I might need to upgrade my motor and do a belt drive before I get into the power draw bar. The noise from the fan always running, and the gear box when it's spinning are terrible and really limits what you can hear from the actual performance of the machine. Not to mention the huge HP loss it seams to have (I've been having trouble keeping 3200 RPM with some cuts I really should be able to do). I think if I re-design the top plate on the mill I can make a much nicer power draw bar.
 
phazertwo said:
I hear you on the rigid taping, it would be super nice. I'm going to attempt some thread milling, the tooling is expensive, and its a much slower operation (at least with single point) but I mostly am going to need 3/8-16 and 1/4-20 threads, and If I get the two tread mills that can do that I think I'm out ~$140. With those two mills I should be able to do anything with a 14-56 TPI thread, assuming it will fit in the ID. For everything 1/2" to 7/8" I will have to do UNF instead of UNC, but I can live with that.

I'm thinking now that I might need to upgrade my motor and do a belt drive before I get into the power draw bar. The noise from the fan always running, and the gear box when it's spinning are terrible and really limits what you can hear from the actual performance of the machine. Not to mention the huge HP loss it seams to have (I've been having trouble keeping 3200 RPM with some cuts I really should be able to do). I think if I re-design the top plate on the mill I can make a much nicer power draw bar.
Click to expand...

People really rave about the motor I have. Its been really solid but I can't say I"ve pushed it hard. It can be had currently for $470 plus, its very heavy so expect close to $100 for shipping. Maybe you want more HP though ? I just ordered another pulley and belt so I can run 1:1 if need be. Ultimately I think it would be best to buy 4 pulleys and run any combination 2:1 ,1:2 or 1:1 with just two belts. To keep my motor form hitting the low basement ceiling I put the pulleys down below where the gearbox was. You could possibly have it exposed up higher to change belts but I also worried about putting too much strain on the spindle bearings due to tensioning the belt. I considered a top bearing too to remove the side load from the belt. I want to experiment with 1:1 to get the supposed 5400 rpm max from this motor ( I've been using 120 hz with a 3500 rpm limit ) at 1:1 rather than the 2:1 I am using now for basically 7000 rpm. Without getting hugely expensive AC bearings for the spindle, I have my doubts I can go much higher RPM with the spindle. Maybe too cautious.... can't be sure until something fails ! lol So if I settle on one belt ratio for all my needs, I can put a bearing on top, then the power draw bar and hopefully it will just run for a long time. One other thing I like about this pulley system is that if I ever crash hard into the table or whatever, the belt might fry instead of a gearbox or the end mill just going through whatever is in its path. I can detail more information... but one thing for sure, if you use J profile belts get GoodYear brand. I believe its what McMaster sells. They are much much better than any other brand.

Maybe send me one of your fusion 360 files of a part you made that bogged down the motor. I'll run it on my mill to see if it bogs my setup. No promises when.. my schedule is difficult to predict. But I'll attempt it....

Jake
 
Last edited:
cut2cut said:
People really rave about the motor I have. Its been really solid but I can't say I"ve pushed it hard. It can be had currently for $470 plus, its very heavy so expect close to $100 for shipping. Maybe you want more HP though ? I just ordered another pulley and belt so I can run 1:1 if need be. Ultimately I think it would be best to buy 4 pulleys and run any combination 2:1 ,1:2 or 1:1 with just two belts. To keep my motor form hitting the low basement ceiling I put the pulleys down below where the gearbox was. You could possibly have it exposed up higher to change belts but I also worried about putting too much strain on the spindle bearings due to tensioning the belt. I considered a top bearing too to remove the side load from the belt. I want to experiment with 1:1 to get the supposed 5400 rpm max from this motor ( I've been using 120 hz with a 3500 rpm limit ) at 1:1 rather than the 2:1 I am using now for basically 7000 rpm. Without getting hugely expensive AC bearings for the spindle, I have my doubts I can go much higher RPM with the spindle. Maybe too cautious.... can't be sure until something fails ! lol So if I settle on one belt ratio for all my needs, I can put a bearing on top, then the power draw bar and hopefully it will just run for a long time. One other thing I like about this pulley system is that if I ever crash hard into the table or whatever, the belt might fry instead of a gearbox or the end mill just going through whatever is in its path. I can detail more information... but one thing for sure, if you use J profile belts get GoodYear brand. I believe its what McMaster sells. They are much much better than any other brand.

Maybe send me one of your fusion 360 files of a part you made that bogged down the motor. I'll run it on my mill to see if it bogs my setup. No promises when.. my schedule is difficult to predict. But I'll attempt it....

Jake
Click to expand...

Hi Jake! Can you post some pictures of your belt drive conversion? Maybe in another thread so we don't drift off the purpose of this thread. I'm asking because my conversion works fine but the drive spline "rattle" is driving me nuts.

Thanks
 
I would like to bump the HP, for no other reason than more is more better.

I think even just changing the current motor to a belt setup (if that's even possible) would net a huge difference in how the mill operates, and if I drop the gear set I'm sure I can start over driving the motor with out too much concern.

PZ
 
HAHA! I have been checking this thread everyday just to make sure my notifications didn't accidentally turn off.

Anyway, not much new hear. How's your project coming pburgh?

PZ
 
Hey Guys,
Sorry, i haven't been getting the notifications. Going a little slow right now. Having back problems. I'm getting an MRI this friday. Been trying to spend some time in the garage to work on the mill. I've extended my air to the garage, so i hope to start on the PDB soon. I'm trying to tune the motors and i'm using a digital indicator. They seem a little touchy. What type/brand of indicators do you use?

Regards,
Doug
 
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