PM 3520B Tailstock Swing Away problem

[Ricc Havens]

I just got a new Powermatic Tailstock swing away. It's marketed as fitting the 3520, 3520A, 3520B amd 2020.

I have the 3520B. I installed it per instructions and used a straight edge to make sure the swing away was level and even with the lathe bed ways. When I slide the tailstock onto the swing away I only get about 3/4ths the way onto teh swing away before the tailstock won't move any more. But it's not far enough back to let the clamp block clear the lathe so it won't swing away.

I have checked the swing away for burrs and used a micrometer to check the thickness of the ways and they are the same thickness as the lathe ways. I even loosed the locknut on the bottom of the tailstock clamp block to give it a little more room. But still no luck.

Anyone else have the same issue and have a fix?
Thanks
Ricc

[Dick Mahany]

Could the sides that the extension ways are welded to have insufficient clearance (space between them too narrow)? If so then even if the ways are correct, they may be binding against the sides of the locking plate under the tailstock and limiting movement.

[Ken Fitzgerald]

Could the sides that the extension ways are welded to have insufficient clearance (space between them too narrow)? If so then even if the ways are correct, they may be binding against the sides of the locking plate under the tailstock and limiting movement.

I think Dick's suggestion about the underside of the tailstock is worth investigating. It has been years since I looked at the locking plate on my PM-3520B but if there is a nut there to adjust holding pressure on the ways, it might be worth the effort to see if loosening the nut, thus decreasing the locking pressure, might allow the tailstock to come all the way out as desired. Maybe the ways on the swing-away extension are thicker than the ways on the bed.

[John K Jordan]

Can you crawl under and see anything with a bright light?

Also, when removing and remounting tailstocks and banjos on various lathes I sometimes have to guide the washer with my fingers to keep it from binding. Try that?

[Joe Kaufman]

Mine has 2 setscrews to adjust the swing away parallel with the bed ways. It could be that the swing away is slightly high or low towards the end of travel of the tailstock. I had difficulty with that adjustment. There was a lot of paint build-up on the underside of the bed ways in that area also. Two other 3520B's I have looked at exhibited the same condition. The tailstock travels a lot easier with the paint removed.

Joe

[Timothy Thorpe Allen]

Like Joe suggests, could the far ends of the swing-away beds be a tad too high or too low, thus at a slight angle relative to the lathe beds? Lay a straight edge along the bedway longitudinally and check that the swing-away is in the same plane as the lathe bed.

[Sam Force]

I have the same issue with my 3520B and the swingaway. Will be following this thread

[Jeff Clode]

Had the same issue which was fixed by loosening the lock nut on the bottom of the tailstock about 1/8- 1/4 turn. Did this after trying to find any other source of obstruction without success (poor alignment, paint buildup etc)
Jeff

[Ricc Havens]

Mine has 2 setscrews to adjust the swing away parallel with the bed ways. It could be that the swing away is slightly high or low towards the end of travel of the tailstock. I had difficulty with that adjustment. There was a lot of paint build-up on the underside of the bed ways in that area also. Two other 3520B's I have looked at exhibited the same condition. The tailstock travels a lot easier with the paint removed.

Joe


Mine didn't come with adjustment screws just the two mounting screws.

[Ricc Havens]

Like Joe suggests, could the far ends of the swing-away beds be a tad too high or too low, thus at a slight angle relative to the lathe beds? Lay a straight edge along the bedway longitudinally and check that the swing-away is in the same plane as the lathe bed.


Tim, you got it correct. Although the from end was level with the lathe bed it wasn't truely flat the whole length of the swingaway. Their welding must be slightly off. the end of the swingaway was a hair low. I could see a little light under the straight edge. after some trial and error it took some shimming of one strip of duct tap and one strip of masking tale on the bottom edge below the mounting screws along with loosening the tailstock lock nut 1/8 of a turnas Jeff Clode suggested.

I couldn't just loosen the locknut and forego the shimming. I tried no shimming and loosening it more like a 1/2 turn without and the tailstock locking arm was almost horizontal and not much locking pressure.)

Thanks for the help guys!!
Ricc