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Pm-932 vs PM-30

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Djl338

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#1
Hi everyone
New to the forum, been doing lots of searches, reading and learning. I currently own a microlux mill, 3/4 hp brushless dc motor which I like, installed a dro and power feed, also things I’m thinking I really need. The downside is there’s not enough “real estate” for some projects. Most of what I do is automotive, vintage restorations making NLA parts, fittings Boring carbs etc, threading .Aluminum and mild steel materials. I’ve been reading through the posts from owners with both machines and it’s a hard decision, I really like dialing in the r.p.m. the microlux peaks at 2600 r.p.m., not so-much torque at the Lower speeds but does ok.
Seems like the 932 has lots of features for the money and at 1000+ lbs assume it’s a fairly stable machine, power down feed installed is also a plus for me, not sure about the r.p.m. Limitations for aluminum or if that’s even a concern. On the PM-30, also has some nice features, belt drive is the real plus for me, but they’re out of stock for a while, I can wait.I’ve read of some VFD mods on the 932 but not sure I want to go down that road and don’t want to void a really nice 3-year warranty.
Any advice fro the experts?, I’m not a machinist, and haven’t worked a full-size mill so have a minimal database on personal knowledge.
BTW everyone on this forum seems really nice, respectful, helpful and not condescending which is really makes this forum a pleasure to read and learn and unique among others.
Thanks again
David
 

shooter123456

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#2
Im not an expert, but maybe I can help compare the two.

The PM-30 has a 2 HP brushless motor which is variable speed, while the PM-932 is single speed with gears. The gearing means the 932 will have the motor running at its peak torque all the time, so the lower speeds won't lose torque the same way the PM-30 would. For manual machining, that may be the better option, since a lot of the cutting happens at lower speeds.

In terms of spindle speed, on a manual machine, I don't think the lower spindle speed is a huge deal. On a CNC, you really do want a higher speed spindle for working in aluminum, but you won't get there with a manual typically. For example, at 1970 RPM, 3 flutes, and .005 IPT, you need to get it moving at 30 IPM. That's not generally going to happen without CNC.

You mentioned the power down feed which I think would be a nice option, but that also adds $800 to the price. You could probably add a power down feed to either one for a lot less.

The two are about 300 lbs difference when you don't count the base. I don't think the base weight adds a ton to the machines rigidity, so I wouldn't consider it. The PM-30 also has more travels compared to the 930. That means the 930 will be more rigid since it is heavier and has less travel. For manual work, I would find that preferable, so long as you don't need the extra space. When cutting manually, I prefer bigger cuts going slower, so it would need the extra rigidity.

I hope that helps a little.
 

Djl338

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Shooter, thanks! , that more than helpful, it’s a great comparison and brought up things I didn’t think about or know, which at my stage is minimal. The point about the motor on the 932 running at peak torque at all times sort-of sways me in that direction. I saw a couple of YouTube’s with guys using a PDF for boring and seemed like a nice feature, but as you pointed out, a fairly expensive feature. I don’t plan on adapting to CNC so no worries there, Again, thanks for taking the time to compare these machines.
David
 

38Bill

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#4
"You mentioned the power down feed which I think would be a nice option, but that also adds $800 to the price. You could probably add a power down feed to either one for a lot less."

Doesn't the PM932 with the power down feed also include power X and Z?
 

shooter123456

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"You mentioned the power down feed which I think would be a nice option, but that also adds $800 to the price. You could probably add a power down feed to either one for a lot less."

Doesn't the PM932 with the power down feed also include power X and Z?
Yes it looks like it does. I missed that. I thought the positioning motor was standard on all of them and the X axis power feed was an extra.
 

Djl338

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Bill, there’s a 5-option menu, from basic to space shuttle version, but I also didn’t realize the Power down feed included the other axes... little less painful when I look at it that way!
 

mcdanlj

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On the PM-30, also has some nice features, belt drive is the real plus for me, but they’re out of stock for a while, I can wait.
As a point of reference, I ordered my PM-30 in late June, and I apparently barely missed a late July shipment. I understand that my mill is included in a shipment that has arrived at QMT (probably the same inbound shipment as @sfsteel 's new PM-30), and that my mill is being prepared to ship out now (I ordered it with DROs). I got the impression that this shipment took longer than they expected to arrive, so maybe the tariff war is getting in the way.

I’ve read of some VFD mods on the 932 but not sure I want to go down that road and don’t want to void a really nice 3-year warranty.
If I were ordering a gearhead mill or lathe, I think I would just go 3Ø and consider the VFD part of the initial acquisition cost. Does @qualitymachinetools really void warranty for adding VFD? (I never asked before because belt-driven DC makes more sense for me right now anyway.)

Also, it looks like the 932 includes X and Z power feed even without PDF, unless you back out to the "BASIC" model. I bought the PM-30 with the X power feed option, but since a Z power feed isn't available as an option for the PM-30, I guess I'll be making a shop-made Z power feed.
 

mksj

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I would contact QMT as far as warranty coverage, in my discussions with them in the past (and having done numerous VFD conversions including the 932), the mechanics of the machine are still covered. QMT also sells the Hitachi WJ200 VFDs which work well, some people have also used the Teco L510 which is less expensive but doesn't support an external braking resistor. Three phase motors tend to be more reliable than single phase, in particular with frequent start/stops. A gear head will be louder vs. a belt drive. The higher RPM is a plus in softer materials (like aluminum), but if you want to remove a lot of material use a rougher endmill, you will be limited by the drive feed rate. Rigidity wise, the additional weight of the 932 is a plus, but then it depends on the work you are doing. If smaller parts, I doubt you would notice a difference between the machines. The DC drives tend to be more powerful at lower motor speeds vs. a VFD drive, but the latter can be operated at higher RPMs to give better performance (my VFD knee mill operates from 20-200 Hz). The VFD conversions I have done for 932-940 owners, a typical motor operating range is 20-75Hz, your top speed is limited by the gearbox. The stock 932 has a high speed spindle RPM of 1970, with a VFD you could push it a bit higher, maybe 2300-2400 RPM, I wouldn't want to go any higher. So the VFD is more for speed flexibility as opposed to top end speed.

Variable speed is great for dialing in the sweet spot, but you can get by with 6 fixed speeds. On the 932, I would definitely recommend a minimum of the 932M (power X and Z feeds), cranking the head gets old very quickly especially with the heavier heads. PDF, well depends if you think you are going to use it, so boils down to the type of work you are doing. I had PDF on my previous benchtop and my current knee mill, in 6+ years I have yet to use it, but if you are going to do boring, it gives a smoother finish then by hand.

Axis travel is often overlooked, it was the one major limiting factor in my previous benchtop mill, in particular the Y axis. Add a DRO scale, and a large vise any your Y travel disappears very quickly, also Z axis height/travel.

So no clear answer, either would work very well. Cost wise with X axis drives they are very close.
 

Djl338

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Thanks, reading through all the pluses and minuses, and past reviews, I think I’ll go with the 932 with all the options. I’ll see how I like the drive, if not there’s always the option of speaking with PM about warranties and VFD’s. I’m not a production shop, I restore vintage German cars, and parts aren’t always available. i Also want to be able to do some carburetors bores and face, warped mounting plates on 50 year old Solex carburetors (sending them out for that costs about half the price of the new machine). I made the decision to upgrade from my current small mill after finding that an axial indicator can’t be put into the spindle without removing the workpiece...kinda defeats the purpose
 

mksj

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i Also want to be able to do some carburetors bores and face, warped mounting plates on 50 year old Solex carburetors (sending them out for that costs about half the price of the new machine).
Very cool, both should get the job done and be a major step up. I do like that the larger benchtop mills come with a power Z Drive, was one of the first things I built for my last mill. Please be aware the the Z axis height table to head can get eaten up very quickly, when you add the vise height, a face mill and the R8 arbor. On my setup I loose about 6" using a 6" vise, and a 4" face mill with R8 Arbor. So if you were surfacing something tall like a manifold or a head you may be limited. The PM-940M has an extra 4" of head to table height (22" vs. 18"), the motor is 2Hp vs. the 932M which is 1.5Hp, Y travel is 12" vs. 8". I always say buy once, cry once. One reason why I sold my old benchtop mill was the limited Y travel which was 8".
 

Djl338

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Thanks, the y axis travel gave me a bit of pause, but I did some measurements and what-if’d the parts and mounting and I’m pretty sure it will work for me. I did look at the pm40 and I know it’s more machine, but knowing how my mind works after many years of saying to myself “ it’s only this much more”, I reeled myself in. My wife puts it like this, I could go car shopping for a Fiat and come home with a Ferrari ‘cause it was just a bit more (largely exaggerated)
 

Djl338

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Mkjs, thanks for your time and help. The 932 is in the shop and I’m already convinced that a bit of r.p.m. control would be nice...So, I called QMT, and have a 2hp 220v 3-phase motor on the way, they said warranty issues, baring spinning it past 2300 or so isn’t an issue, so I’m sold. Reading through the many threads, it was mentioned you may have a parts list of things to make it beyond the basics of the vfd? It would be nice not to need to reinvent the wheel, and I’ve read some threads of installs, but want to have all parts in-hand before I move ahead. I purchased a teco L510-202-H1-U from marshal-wolf, super helpful company, just looking for what I need to fill the gaps.
Thanks in advance
David
 

Rickwjenn

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I am starting to make car restoration and performance mod parts for american muscle cars and bought the PM-940 CNC....

My comment would be GET THE VFD. The ability to linearly change spindle speed up/down instead of gear/pulley changes is a big improvement. Plus if you ever go CNC via an Acorn board, this is the set up IMO. The 3 phase motor down stream of VFD controller is super smooth and the finish machine quality is often called out vs. single phase.

Just my view and worth what you paid for it.
 

Djl338

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Rick, I’m with you, parts are on the way. Well, the motor and VFD. Where do you keep your gearing with a vfd? I read one thread where they were talking about belts on drill presses, but haven’t found info on gear head.
David
 

Rickwjenn

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David. I have a Delta VFD that drives my PM-940 mill. The spindle has a high and low gear setting. I have left mine in high, and the VFD goes as low as 300 rpm to 3100 rpm on this range. I have not tried the low setting but believe it drops by ratio of 2 so it should be 150 rpm to 1550 rpm on the VFD's 0 V to 10 V input.

So far, I have no need to change the gear setting - just leave in high and change spindle speed via the CNC program or with the Centroid Remote control RPG. The RGP can overide a running CNC program's set spindle speed as needed (i.e. like for some of my early CNC programs :) )
 

Djl338

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Rick, that’s helpful thanks. This vfd thing has been a mystery to me until I found the info here, and watched some really well done YouTube’s on how and what they did. Seems like a no-brainer to install, it would have been a nice additional option from QMS,
 

mksj

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PM-932 has 6 speed gearbox, requirements are a bit different for CNC, but agree with benefits of VFD. There are previous threads with details, but may be hard to find.
 

Rickwjenn

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If you do not have a CNC motion controller, isn't easy to wire? Take your 220 1 phase to the VFD controller and the 3 Phase 220V out is wired to 3PH motor.... There is no 0-10V input signal and you simply change speed with the VFD speed knob? Attached is wiring for my Delta VFD if I was going to use manual speed control (i.e. no CNC controller or RPG remote).

1538095223590.png
 

Djl338

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Thanks Rick, the threads I read here, and bits and pieces of what I found in them was related to altering the stock control buttons on the panel to work the vfd. I don’t mind starting simple, and working my way to a more complex convenient setup. I would like to, use an r.p.m. display. Some of the setups used a proximity type and they didn’t use the magnetic sensor or maybe I missed it, us but programmed the The vfd to read it. There is a good chance I misunderstood that
 
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