Pm-940m-cnc (pre-assembled)

phazertwo said:
20k steps/rev is A LOT! My drives are set to 1600 and 2000 would be the max that I would go. At 2000 steps/rev, each step is 0.0001" linear movement of the table. At 20k steps/rev your table is moving 0.00001" per step.... or one, one-hundred-thousands of an inch... Which is an insane number, especially considering the run out on the spindle bearings is only rated at like 0.0015" or 150 x larger than your step distance.

Also, just to run 100IPM your going to need 166khz/axis. I can't imagine that the nMotion/M3 handles that well. I would try bumping it down to 2k steps/rev and give it a shot, that essentially reduces the load on the nMotion/M3 by 10. Also, stepper motors get hot, I have never measured mine so I don't know how hot they get, but they feel toasty. Due to the nature of a stepper, heating will always be an issue.

Is there a reason you are not using Fusion 360 for CAM?

PZ
Click to expand...

Yeah it does seem like a lot, but having the drivers set to 1600 (what they were by default, also what you have in your picture above) and 8000 in Mach3 resulted in really noisy movement. Everything is so much quieter and smoother now.

I just am not quite used to Fusion 360 yet, but I'll try outputting the same file from both it and Aspire and see what's going on.
 
Steppers do run smoother when you increase the steps/rev, but the loose torque as well. I found that it wasn't an issues for me as long as I was running above 6IPM, which rarely ever happens anyway.

As with everything, there are trade offs. Just one of the reasons I'm contemplating servos.

PZ
 
Hello, my pm940vs CNC will be coming in this week. I am a gunsmith and wanted this mill to do small “ manual” jobs and hopefully later make parts if needed. After reading this thread I am kinda nervous about everything I need to do to “ set up” the mill when it gets here. If someone if very experienced with this mill, I would love to talk on the phone about it and set up. I don’t know if one can send private messages to each other but I will send someone my number if they would be so kind to give me some of their time. Thanks
 
To private message just mouse over the name, and then click "start conversation"


<- Name should appear about here.

The only issue I see with you trying to use the machine manually, is that the spindle is controlled with a VFD and it needs a signal from the controller in order to fire up, and change speed. Your best bet is probably to just get it set up with Mach 3 and feed spindle commands into the controller, but there are other ways to do it if you're interested. Also, the steppers seem cog pretty bad every 1.8° even when de-energized, which could make manual precision operations tricky.

As for setup, first thing I would do is tighten all the wire terminals you can. It seems to be a re-accruing issues with these mills, most likely from the amount of time it spends in transit. After that it's not to bad to get it going, especially if you have some experience with Mach 3.

Not sure how much help I can be, considering how much I have changed mine. But I'd be willing to talk to you some night after work (I'm near Denver).

Here is a link to the mods I've made so far:
https://www.hobby-machinist.com/threads/another-pm940-cnc-vs-thread.68291/

PZ
 
I did the wall mount for the electronics to mine a while back. Some of the conduit runs have been pulled apart. Do you know where I can get new conduit in longer lengths to protect my wires? I have found a few things, but they are in 100' min rolls.

Joe
 
megaplow said:
I did the wall mount for the electronics to mine a while back. Some of the conduit runs have been pulled apart. Do you know where I can get new conduit in longer lengths to protect my wires? I have found a few things, but they are in 100' min rolls.

Joe
Click to expand...

I have the same issue. I tried to find the same stuff but couldn’t. By coincidence, just yesterday I thought to ask Precision Mathews if there is a source for the original.
Maybe we could do a joint venture on the 100’ roll ? There may be others . Can you share what you found and pricing , etc ?

Cheers,
Jake
 
Hi Guys,

I was just reading posts and saw yours about the conduit. So I am a bit late, but I could use some of the conduit. When I moved my electronics cabinet to the right hand side of the machine and rotated it so that the doors opened to the front a couple of the conduits were a little short, especially the one to the x-stepper which is on the other side of the machine. I had to drill couple new holes in the cabinet and move some of wires around to make all of them reach where they needed to go. I just looked again, maybe it is the same/similar as: https://www.heyco.com/Liquid_Tight_Conduit_Fittings/?sub=flexible-pvc-conduit-tubing-fittings The end caps look a lot like: https://www.heyco.com/Liquid_Tight_...ittings&section=Liquid_Tight_Conduit_Fittings

By the way, earlier in this post there was conversation about a spline wrench. Since I live in Pittsburgh, I went to see PM. Matt had one at the time and helped me out. It may have been a sales sample someone gave him. I have no info on the manufacturer other than "Made in the USA". It is nice and big/thick. I will attach a couple of photos. It is made of Al and with the thickness it does not bung up the splines! I don't see it on the PM web site, but maybe Matt can get them, or can let us know where to purchase it. I looked around on the web, but never found anything quite like this one. I put a rule next to the wrench so you could get a perspective on its length and thickness.

Dave
288156288157
 
megaplow said:
I did the wall mount for the electronics to mine a while back. Some of the conduit runs have been pulled apart. Do you know where I can get new conduit in longer lengths to protect my wires? I have found a few things, but they are in 100' min rolls.

Joe
Click to expand...

If it is the stuff I am thinking of, it is available at Lowes, Home Depot and Menards in the electrical section. Here is a link to Lowes. Lowes Liquidtight Flexible Conduit
It is also available at McMaster. https://www.mcmaster.com/electrical-conduit Scroll down on the McMaster page and you will see all variations. I am thinking they are not the cheapest but buying a few feet from them would be cheaper than a 100' roll.
 
Thanks 7milesup.
The "Liquid-Tight Flexible Plastic Conduit" at McMaster might actually be the same as the Heyco and is sold in smaller lengths. However, I have looked at the Lowes and HDepot sites and their product is way to stiff so will not make a small radius. I have a number of lengths of something similar to these already made up with connectors. They are stronger and more heavy duty. I used one of them on a position where there was no motion. However, you need the flexibility on moving tables etc. By the way, the dimension drawings of the conduit and the fittings on Heyco maybe handy.

Dave
 
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