PM-932 Spindle Runout, Cheap chuck issues, and head wobble when boring, Gibs adjustment from factory?

[tlmartin84]

Lots of questions!

Just got my new mill, cleaned it up, and started setting it up.

I had some issues right off the bat.

The 3 Jaw Chuck had runout of .015". I took it off, and checked the R8 arbor at the top of the shank, and the bottom. Checked within .001". So I got the other 3 jaw that came with the mill, and slapped it on....SAME THING 0.015"... No clue whatsup with it, dropped it off at a buddies to let him check them. I could understand one, but both being messed up? Maybe it was the arbor, but t checked in both the mill spindle and on the lathe?

Oh...and when I went to take the drawbar out, the threads snapped in the R8 arbor, looked to be a defect in the metal. PM sent me a new one.

I ordered a MT3 and R8 High Precision Chuck Keyless chuck after the problems with the others. Put it in the Mill and checked the runout. It was 0.002", much better.

I also checked the Spindle runout, it appeared to be 0.0005"-.001". Does that seem normal?

I bought some brand new DrillHog M7 bits and wanted to try everything out. I put a 3/4" in and drilled a hole in a piece of 1/4" plate. The hole ended up kind of triangular, and there was noticeable movement in the Head. Everything seems tight. Maybe it is the Z Gibs? At this point I can't imagine milling anything of large capacity after seeing the movement in the head. Is any of this "Normal"?

Do you need to adjust the Gibs straight from the factory?

 

[Z2V]

I would take it apart, clean and lube everything, then adjust. That's what I did with the new lathe. Time very well spent.

 

[RJSakowski]

Drill bits tend to cut holes with one more side than the number of flutes. The lack of a pilot hole and thinner work seems to enhance the process. A lack of adequate rigidty will also affect the outcome. A 3/4" hole is a fairly large hole for a small mill. I usually work up to that size by drilling a pilot hole, followed by an intermediate size and then the final diameter. When drilling large diameter holes it would be a good practice to lock the x and y ways. Smaller machines can do some amazing work but they are definitely not in the same league as the big industrial machines.

I would definitely check the gib adjustments. Unless the vendor specifically makes those adjustments prior to shipping, I would expect any Asian machine to need some adjustments prior to use. Many purchasers of Asian machines strip them down and clean,. inspect, lube, and adjust before use.

 

[darkzero]

Your mill will have no problem drilling a 3/4" hole but drilling a 3/4" hole in 1/4" plate without a pilot hole is bound to give you undesirable results.

 

[mikey]

I ordered a MT3 and R8 High Precision Chuck Keyless chuck after the problems with the others. Put it in the Mill and checked the runout. It was 0.002", much better.

I also checked the Spindle runout, it appeared to be 0.0005"-.001". Does that seem normal?

I bought some brand new DrillHog M7 bits and wanted to try everything out. I put a 3/4" in and drilled a hole in a piece of 1/4" plate. The hole ended up kind of triangular, and there was noticeable movement in the Head. Everything seems tight. Maybe it is the Z Gibs? At this point I can't imagine milling anything of large capacity after seeing the movement in the head. Is any of this "Normal"?

Do you need to adjust the Gibs straight from the factory?

Just out of curiosity, how did you check the spindle for concentricity? 0.0005" to 0.001" is somewhat ambiguous but it also sounds a bit much to me. Did you get this range of runout with the mill running?

The stated runout of the high precision chuck from PM is +/- 0.001". How did you arrive at 0.002" TIR? With the machine running against something held in the chuck?

A big drill produces big cutting forces so a lot depends on how you drilled the hole. If you used a spotting drill and then a pilot drill then the hole should be a bit more accurate. If not, then the hole will typically be triangular and this is especially true if you did not use enough down feed to keep the drill cutting continuously. Since we are not clear on your procedure or technique, everything is a guess.

As for whether or not the gibs need adjustment, maybe so but I would think the table gibs are more to blame than the Z axis. A big drill will push the table around if the gibs are not adjusted well and I suggest you start there. Then lock the X and Y axes and try drilling again to see how things turn out.

Not being critical. Just need more info to be more helpful to you.

 

[tlmartin84]

Just out of curiosity, how did you check the spindle for concentricity? 0.0005" to 0.001" is somewhat ambiguous but it also sounds a bit much to me. Did you get this range of runout with the mill running? I just placed my dial on the outer lower edge of the spindle, it was the same whether I turned it by hand or with it running.

The stated runout of the high precision chuck from PM is +/- 0.001". How did you arrive at 0.002" TIR? With the machine running against something held in the chuck? I placed a bit I in the chuck (Checked it in lathe prior) and then set my dial on it and turned the spindle. (having said this .001" at the spindle plus .001" in the chuck would get to that .002".

A big drill produces big cutting forces so a lot depends on how you drilled the hole. If you used a spotting drill and then a pilot drill then the hole should be a bit more accurate. If not, then the hole will typically be triangular and this is especially true if you did not use enough down feed to keep the drill cutting continuously. Since we are not clear on your procedure or technique, everything is a guess. I do not have a PDF. But I did keep good pressure on it, and it turned some nice ribbons, only letting off to break them. I did not predrill, the bit manufacture recommends against pilot drilling. It did however clean up really nice when I went to a 7/8" bit.

As for whether or not the gibs need adjustment, maybe so but I would think the table gibs are more to blame than the Z axis. A big drill will push the table around if the gibs are not adjusted well and I suggest you start there. Then lock the X and Y axes and try drilling again to see how things turn out. After the first hole I did lock the axis. It seemed to help some, but there still seemed to be movement. It appeared to be in the head/spindle flexing but maybe my eyes were deceiving me, and it was the table????

I'm going to recheck the tightness of everything, I just expected this thing to be more rigid than what I'm seeing. My only experience is with a WW2 era Bridgeport which never moved. Maybe I am asking too much of it, but I just didn't expect a 3/4" hole to be too much.........

And, more than likely, I have something setup wrong.

Not being critical. Just need more info to be more helpful to you.

 

[mikey]

A DI run on the outside of the spindle is probably not going to give you an accurate reading. I suggest a dial test indicator run inside a clean taper. Clean the taper well and mark the outside of the spindle with a Sharpie, then bring the tip of the DTI into contact just inside the spindle taper. If you can, rig a pointer to align with your Sharpie mark. Zero the dial and make one complete revolution of the spindle by hand and realign your marks. The DTI should read zero. If so, make another revolution and look for deviation from zero to get your TIR. Do this in several places inside the taper to be sure the TIR repeats and that will be your TIR or concentricity of the spindle. I would expect a new spindle to run under 0.0005".

Once you know the concentricity of the spindle then checking run out on the chuck "might" mean something. If it is an integral shank chuck then maybe it will fall within specs. If it has an arbor then much depends on how the arbor was installed. Assuming it was done correctly, chuck up an accurately ground pin and preload the DI with about 0.015" and zero the dial. Then mark the chuck, do one rev to check repeatability and then check for TIR. Again, do not do this under power.

I agree - check all the gibs and see how your cuts turn out. I'm not sure I would judge a mill by how well it drills big holes but you're right; you shouldn't see the head moving with an acceptable cut.