Some questions about my 932

[mas]

Like many here, I took possession of a PM-932 a few weeks ago. This is my first real piece of machinery (not counting the tiny 7x10 Hazard Fraught lathe I bought on a whim, which sits mostly unused until I can convince myself to put the purchase price's worth of mods in it, just to make it a usable machine... but I digress), and marks my first serious intent to venture into the world of metalworking. I normally hate to admit stupidity, but I'm an electrical guy by trade and I'm a bit lost with some of this stuff, so I guess I'll swallow my pride and commence the questions

First off... The machine comes with a box of goodies. In the box is the drill chuck and arbor, and a second arbor with a thread in the business end and some steel blocks with socket head screws counterbored into them on the sides. For the life of me I cannot figure out the function of this arbor! Someone care to enlighten me?

Next. How much oil should be in the gear head? I think the manual says halfway up the sight glass. Mine is closer to a quarter or third up the sight glass, is that OK or am I inadvertently starving the top of the gearset of lubricant?

I ask the former question as a precursor to this one. During prolonged usage, the head gets quite warm, warmer than I would expect for something which does not contain an electrical load. Granted, the motor fan does blow down onto the top of the head, so is this the source of the heat, or does the gearbox in fact get quite warm of its own accord, or maybe does something have more friction than it should? The head is not what I would call "quiet" in operation, although I don't have any baseline for how it "should" sound. It's certainly much louder than a drill press.

Has anyone built a coolant system for this unit, since it is not included? Is there a standard reference design lurking around here somewhere?

Early next year will see the addition of a DRO. Is there any particular advantage to the Easson ES-12 type that makes it worth two or three hundred dollars more than a traditional segment-type display?

There's a couple of other things on my mind, but I think I'll read over the Grizzly manual a couple of times to avoid asking too many questions that can be easily found. Thanks in advance!

 

[Ray C]

HI. Congrats...

If you could show a pic of the accessories, that would be great as I havent seen how the 932s are shipped.

The sight glass should show half way after its been sitting for a couple hours. It takes that long for the heavy oil to settle. How long do you consider prolonged usage? On my machine, after 30-40 minutes of regular use, the motor will get about as hot as a cup of coffee and the gearbox will be lukewarm. Being slightly low on oil will not harm things unless you tilt the head at a sharp angle. Still, that oil splashes around like crazy in there... Yes, it is louder than a drill press but I'd be hard pressed to describe a sound with the written word. My wife had a breadmixer that was about the same sound and it's quieter than an old dishwasher we once had. Sound varies based on RPM -louder as you go faster.

Also, please unplug the unit and check the wires in the motor terminal box. There was one case where the wires were loose. This is a 10 minute double check.

Like many here, I took possession of a PM-932 a few weeks ago. This is my first real piece of machinery (not counting the tiny 7x10 Hazard Fraught lathe I bought on a whim, which sits mostly unused until I can convince myself to put the purchase price's worth of mods in it, just to make it a usable machine... but I digress), and marks my first serious intent to venture into the world of metalworking. I normally hate to admit stupidity, but I'm an electrical guy by trade and I'm a bit lost with some of this stuff, so I guess I'll swallow my pride and commence the questions

First off... The machine comes with a box of goodies. In the box is the drill chuck and arbor, and a second arbor with a thread in the business end and some steel blocks with socket head screws counterbored into them on the sides. For the life of me I cannot figure out the function of this arbor! Someone care to enlighten me?

Next. How much oil should be in the gear head? I think the manual says halfway up the sight glass. Mine is closer to a quarter or third up the sight glass, is that OK or am I inadvertently starving the top of the gearset of lubricant?

I ask the former question as a precursor to this one. During prolonged usage, the head gets quite warm, warmer than I would expect for something which does not contain an electrical load. Granted, the motor fan does blow down onto the top of the head, so is this the source of the heat, or does the gearbox in fact get quite warm of its own accord, or maybe does something have more friction than it should? The head is not what I would call "quiet" in operation, although I don't have any baseline for how it "should" sound. It's certainly much louder than a drill press.

Has anyone built a coolant system for this unit, since it is not included? Is there a standard reference design lurking around here somewhere?

Early next year will see the addition of a DRO. Is there any particular advantage to the Easson ES-12 type that makes it worth two or three hundred dollars more than a traditional segment-type display?

There's a couple of other things on my mind, but I think I'll read over the Grizzly manual a couple of times to avoid asking too many questions that can be easily found. Thanks in advance!

 

[Ray C]

Oh, BTW: Coolant system... I guess flood coolant is popular but I have no idea why, given the mess and lack of visibility. On fully shielded CNC setups where the operator is in a different room, it makes sense. Many folks -myself included- switched to Kool Mist. Lots here written about it... and the search button will find it all.

A fancy DRO... I don't see it and look forward to other opinions. I have 3 axis on mine and I'm pretty sure I even used the Z axis once -maybe -but I could be wrong. I use the line hole, circle, 1/2 axis and datum point functions on mine regularly -and that's about it.

Ray

 

[qualitymachinetools]

Hi Mas, And Ray, thanks for covering most of that.

The arbor is for a shell or face mill. They just stuck them in there, so we leave them in there. You may find a use for it later on, shell and face mills will fit it, so you never know. Its better than taking them out, and us having a pile of them!

You will also find a few small black square blocks, they come off when the power feed goes on, so just extra parts now.

As far as the head getting warm, after a bit, change the oil out, but do not worry about break in or anything. Just use the mill as you normally would. I have found that during normal use, you are not going to have the machine running for an hour or 2 at a time, normally. Mill a bit, shut it off, measure, mill some more, etc.

So a lot of people end up with that. Just run it and use it. It will break in as you use it. And as long as the oil is in the sight glass for sure, its close enough. Trust me, oil is flying around everywhere in there, so no problem there.

Thats a good tip for the motor wires too. I have had the guys check them recently, but not sure which ones they got and did not as far as when they shipped, so its always a good idea to check them.

The ES-12 DRO is nice, it has the same functions as the ES-8A, but just a prettier screen, with graphics. For example, if you are doing a bolt circle, it will show you a picture of where to go, instead of with the ES-8A, it just shows the numbers. Both work, just a different way to do it.

If you come up with more questions, feel free to email me direct, I check this, but not too often.

Thank you, and good luck with your projects!

 

[mas]

Good thing you guys said something. I checked my motor screws and found them all to be somewhat less than tight. They weren't 'falling out' loose, but I was able to tighten them all half or three quarters of a turn, and at least one a full turn. In doing so I noticed that one of the rear motor connections had only a screw's width of grab on the motor lead, and that the plastic around this and the adjacent screw were starting to see discoloration or deformation.


The rear of the block. The upper left wire sure doesn't look like it's in there very far.


Removing the Z1 connection, we can see that it is just beginning to show signs of heat damage. Meanwhile, the block to the right has obvious deformation.


Here's the removed wire from the upper left motor connection. I guess the screw had "enough" grip on the wire, but I sure like to see more. You can also clearly see the deformation in the center screw from this angle.

I tried putting the wire back in and tightening it properly, but before I got it snug (I wasn't even torquing that hard!) the threaded brass insert cracked. So I guess I'm in the market for a new terminal block as well.

While we're at it, in case Matt's listening, I wouldn't mind a quote on a new electrical box... mine got a little bit of force during installation:

(Nothing a little duct tape and some zip ties couldn't fix, for the time being)

Now, regarding temperature. When I said "prolonged" I meant about 90 minutes at about 90-95% duty... was hogging out a bunch of material from an aluminum block, stopping only to double-check measurements every once in a while. By the by, I took some thermal images of the mill after an hour of un-loaded operation this evening (10 minutes per speed), since I didn't have another block to destroy. The surface of the motor hits at least 60C and the top of the spindle gets to at least 75C (the camera can't figure out shiny surfaces very well, so it usually reads a little low). I suspect the temperature may end up higher if the machine was actually "doing something". I guess 75 isn't all THAT hot, for machinery... feels pretty warm to the touch though!

Motor


Spindle


Interestingly enough, through the observation port (broken corner) of my electrical box, the innards get to 60+ degrees as well. I wonder what that means for longevity of those components... not that there's much in there to feel the effects of temperature-induced accelerated aging.

Here's the "mystery arbor" I was talking about (even though it's not a mystery anymore):

I still don't quite grasp how it works, but at least I know what to search for now.

The mist system is a good suggestion... part of my brain somehow didn't grasp the fact that a 1000-RPM spinning articulated shaft may throw an applied liquid everywhere in the immediate vicinity. I don't have a compressor, though, so for the moment I guess I'll continue applying WD-40 with a paintbrush, and continue researching.