Who has a PM-932V? Couple questions

[arty1]

I'm about to place an order for a PM-932V...basically identical to the 932M except with VFD. The VFD components are housed in a (somewhat large) cabinet on the rear of the square column. Due to space limitations in my shop I have to place the mill against a wall, which will block access to this cabinet. I'm hoping to relocate the cabinet (lengthening cables if needed) down below to one side of the stand.

1. What are the dimensions of this VFD cabinet? I asked PM and they say they don't have access to that information and the manual hasn't been updated yet to include info on the VFD stuff.
2. Would it be a big hassle to relocate this cabinet? Seems pretty straight forward to me but thought I'd better ask before I make the purchase.
Thanks

 

[B2]

I have a PM940M-CNC which has a much larger cabinet and weighted about 200#s but it is much bigger than yours. I flipped it around and mounted it to the column side so that the doors faced forward. A couple of inch standoffs would have been nice so that the doors better cleared the sides of the mill. I cannot comment on this style mounting for your machine as I know nothing about the column strength/size. However, there is a picture of the insides of the 932V cabinet on the PM web site. It shows the VFD and you can look up the dimensions of a standard 2HP Delta VFD and from this you can roughly scale the dimensions to give you a rough idea of the overall size. (my wag from looking at the picture is that the cabinet dimensions are less than or about 18Wx24H" by ~7-8" deep.) You mentioned mounting it low. Keep it high enough that the cutting debris and coolant and lubricant do not splash or run into it.

You can figure the hassle of rewiring it by the number of wires coming out of it to the mill controls. Not much compared to my CNC, but you may have to lengthen the cables depending upon how far away you place the cabinet. Some of the metric size encased wires can be a little hard to find.

Good Luck.

Dave L.

 

[graham-xrf]

Just a general observation about VFDs in enclosures..

The "somewhat large" aspect for the enclosure boxes for electronics involving VFD, motor drives, switching, etc. is sometimes deliberate. Any kind of semiconductor switching of motor energy usually involves heatsinks, and most of the enclosures for servo stuff I ever used ended up quite large, with DIN rail heatsinks mounting the SSRs, or the motor drives had big heat sinks. I usually used box fan cooling with replaceable filter inlets.

Where the surface area of the box was not enough to dissipate the heat, and we wanted a compact build, I would opt for a large heatsink with low °C/Watt specification mounted on the outside of the box, and the semiconductor SSRs were on the inside, where the connections could be safely enclosed. It always meant a cut-out in the back of the box, so the bits needing cooling could be directly fixed onto the heatsink, with suitable heatsink compound at the interface.

VFDs for typical machine tool motors, up to a couple of HP are considered "small", and might well be OK simply mounted in a large(ish) enclosure. The thing to know is that the junction temperatures of the electronics inside depends on the ambient temperature around the heatsink. If (say) the temperature outside is reasonably warm, say 25C or 28C, the temperature inside the box might be 35C or 40C, which limits the room a VFD entirely inside the box has to stoke up it's heatsink.

I'm just saying that the "large" size of the enclosure might be a sensible design feature. That said, I have come across a lot of stuff where designers just didn't care, and overheat failures were the norm.

 

[arty1]

B2, now that’s an idea I haven’t considered…flip the box around and mount on the side of the column. I’ll have to think about that one some more. Quick glance looks like this approach might eliminate a few cables needing to be lengthened. I didn’t quite follow your last comment about “metric sized encased wires”...can you clarify? Are you referring to cable assemblies that have over-molded insulation?

Graham, yeah agreed. Being a retired M.E. one of my responsibilities was thermal analysis of circuit cards and electronic packaging. Everything you mentioned is spot on. In the photos and the few videos I could find of the enclosure I didn’t notice any exposed heatsinks or even a fan. There is a small vent area (perf pattern of holes) near the top of the enclosure, but that’s about it for any obvious thermal management. In any case, I’d probably add a small muffin fan to the enclosure.

I think I’m going to go forward with the purchase but will weld up my own stand. If I don’t end up mounting the box on the side of the column I’ll incorporate it into the stand, most likely with the door facing the front. Thanks for the comments.

 

[B2]

URL to Photo of my machine below. Box mounted on the side and the stand is on casters. However, after I get it where I want it I block it off the casters for stability. I can put in on the casters and wheel it out for working on the back if need be. I also put down thin bath shower rubber under it to keep the oil off the concrete.

https://www.hobby-machinist.com/attachments/pm940m-cnc-front-i520-jpg.274812/


I should have put stand offs between the box and the column so that the doors cleared better. After I did mine I suggested this to @ptrotter and he did so. He did his own CNC conversion and so his box was smaller than mine from the factory.

The cables on many of the machines come in a plastic flex type cable wrap and this is what I am talking about. Mine are metric. I swapped some of my cables around and made them work out, but the one that goes to the stepper motor at the end of the x-axis is a stretch. I also had to drill some holes in the top and bottom of the box for the cable exits to be closer to their final destination. The cable wrap stops at the box surface strain relief so you can have plenty of individual wire length inside the box.

Most VFDs have heat sinks built on the back of them and these bolt to the box. In my pm940M case there was a large heavy steel plate which all components were mounted to. So the heat sink was attached to it and this would spread the heat out over large distances quickly.

Dave L.

 

[arty1]

Wow, I see what you mean...that enclosure is LARGE. Regardless of the 932V enclosure size, I'll just have to make it work. I was hoping it would be short enough to fit next to the cast stand. Not looking forward to fabing my own stand so I'm going to ping PM again next week and press them to see if they can get me measurements. Hopefully I'll get a different rep than I spoke to last week.

 

[verbotenwhisky]

I'm about to place an order for a PM-932V...basically identical to the 932M except with VFD. The VFD components are housed in a (somewhat large) cabinet on the rear of the square column. Due to space limitations in my shop I have to place the mill against a wall, which will block access to this cabinet. I'm hoping to relocate the cabinet (lengthening cables if needed) down below to one side of the stand.

1. What are the dimensions of this VFD cabinet? I asked PM and they say they don't have access to that information and the manual hasn't been updated yet to include info on the VFD stuff.
2. Would it be a big hassle to relocate this cabinet? Seems pretty straight forward to me but thought I'd better ask before I make the purchase.
Thanks

The V and M are similar in size and share many of the se parts; but, the big difference is the M is a gear driven unit while the V is belt driven. I have a 940V, I like it a lot....

 

[arty1]

The V and M are similar in size and share many of the se parts; but, the big difference is the M is a gear driven unit while the V is belt driven. I have a 940V, I like it a lot....

Can you take some measurements of the vfd enclosure... overall height, width and depth?
Thanks!

 

[verbotenwhisky]

Can you take some measurements of the vfd enclosure... overall height, width and depth?
Thanks!

15" wide, 21.5" tall and 8.5" deep with the handle adding 1.5" for total depth/clearance of 10". Please remember mine is a PM940V wich over all is a bigger machine; but, I cannot see the box varying to much.

 

[verbotenwhisky]

URL to Photo of my machine below. Box mounted on the side and the stand is on casters. However, after I get it where I want it I block it off the casters for stability. I can put in on the casters and wheel it out for working on the back if need be. I also put down thin bath shower rubber under it to keep the oil off the concrete.

https://www.hobby-machinist.com/attachments/pm940m-cnc-front-i520-jpg.274812/


I should have put stand offs between the box and the column so that the doors cleared better. After I did mine I suggested this to @ptrotter and he did so. He did his own CNC conversion and so his box was smaller than mine from the factory.

The cables on many of the machines come in a plastic flex type cable wrap and this is what I am talking about. Mine are metric. I swapped some of my cables around and made them work out, but the one that goes to the stepper motor at the end of the x-axis is a stretch. I also had to drill some holes in the top and bottom of the box for the cable exits to be closer to their final destination. The cable wrap stops at the box surface strain relief so you can have plenty of individual wire length inside the box.

Most VFDs have heat sinks built on the back of them and these bolt to the box. In my pm940M case there was a large heavy steel plate which all components were mounted to. So the heat sink was attached to it and this would spread the heat out over large distances quickly.

Dave L.

Beautiful machine, you have the same machine but your cabinet is much larger than mine, likely due to extra components for CNC. Mine has a single door.