How to adjust alignment for PM 3520B?

[Dan Forman]

My lathe is just a touch out alignment, but enough to cause vibration issues on small pieces working between centers. The manual doesn't have any info on this. Has anyone had to do this on theirs? Thanks,

Dan

[Scott Hubl]

First try Leveling it.
Take a 4 foot level and make sure the bedways are level the length and check the short side front to back at all four corners.
Believe it or not that cast iron moves.
If you have a low or high spot in the floor were one of the leveling feet sits it can twist it slightly.

[Jim Becker]

Scott's advise is spot on...cast iron will twist and bend just from the feet being out of level. It only takes a small amount to cause the spindle alignment issues you describe. I had them with my Stubby, too, for the same reason.

[Ken Fitzgerald]

Dan.....when I first got mine, it had similar problems. Then I cleaned the bottms of the headstock and the tailstock really good and the problems went away. The excess cosmoline was enough that the centers wouldn't align properly.

[JerHall]

In addition to the good observations above check that the headstock is not rocking slightly. Put your finger on the interface with the bed and see if you can feel any "rocking." If so then it may not be locked down well or the headstock may not be flat on the ways. I added a longer turned locking handle to make it easier to cinch it down. When that didn't do it I cleaned the interface with the ways. When that didn't do it I discovered there was a high spot on the headstock bottom surface under the locking shaft. I lapped it carefully (fine sandpaper on mdf,) even used a mill file for the worst of it. Checked frequently with a straight edge, and that did it. Took a while. More detail and pictures on mustardmonster dot googlepages dot com on the "Mechanical" Page, "Headstock Rocking"

Hope this is not a problem. It was a PITA. Of course if you are under warrantee you should make it PM's problem.

[Dan Forman]

Thanks to all who contributed! Well, thought I had leveled it properly, but when I double checked with a four footer I found it was off just a tad on one corner. That took care of the horizontal alignment issue. I also re-cleaned and waxed the ways and bottoms of the head and tail stock. The vertical alignment is still off, so I suspect I'll have to look at Jer's solution, though getting that headstock off is more than I can do by myself. To clean it, I just slid it halfway off on either end of the bed, so it didn't have to come off. I haven't checked if it rocks, if not, maybe just a shim would work, and it wouldn't need beheading.

Dan

[Scott Hubl]

Just for the heck of it, try raising and lowering the adjustment feet to see if that will help move it into alignment.

It will be back to slightly off on level but it may just twist it in place.

Gonna be a trial and error testing kinda thing.
Good luck

If not then contact Powermatic and see what they can do.

[JerHall]

There have been previous threads indicating that there is a lot of wiggle room on that. And you can't trust the center points to be centered. Mine is off at least a 64th and doesn't cause a problem for me. I could dig those threads up if you want. I wonder about the cause itself. How old is the lathe? Could it be the bearings? or a worn or burred morse taper, or defudgilty with the live center? Does the behavior happen with a chuck and also a drive center? I wouldn't settle on a particular cause just yet. If you do take the headstock off two suggestions:
- A workmate on extended legs comes within inches of matching the ways and provides a stable platform to tilt the headstock and examine it for flat.
- Look for a shiny spot around the locking shaft as evidence that it is high. Mine was. My theory is that the shaft hole was bored after the face was machined, and made a high spot.

If you can't feel a clear rocking on the seam of the headstock and ways I bet it is some other cause.

I know you would you rather be turning than having this hang over you. There has to be a simple solution, it just isn't simple to find.

I am not sure about shimming. Would that prevent you from moving the headstock? I would shim the tailstock before the headstock tho.

Keep us posted.

Jerry

[Dan Forman]

I think all is well now. There was no clear rocking from the head. After just cinching both head and tail down FIRMLY, it seems to be in alignment. It may just have been the head needing a little more oomph behind it to bring it down to level.

The lathe was new in November, so I don't think it's a wear problem. I'm using carbide tipped dead and live centers to turn pens between centers. With such small pieces (2-3" x 3/8 to 1/2"), and fine fit tolerances, it tends to show up a problem more than larger spindle work, such as a table leg. I'm gluing up another blank to give it a try, but I think it will be alright. Hope so anyway.

Dan

[JerHall]

Glad it was simple. You might be well to take a few minutes to turn your self a long handle with ferrel to replace the ball on the headstock handle. Will be easier to reach and give you more leverage to lock it down.