Knowledge You Can Build On — Est. 1998
Tail Stock Quill
Sam Scalzo
Has anyone ever have tail stock Quill freeze up on a Powermatic? It is a 3520A and Powermatic said they did not make them anymore. I asked if the 3520B would work and they said no. I went to one of our club members and look at his 3520B and it was the same size. Only difference mine had the grove on the bottom and his was on the side. I ordered a new quill and drive bolt and it works perfect.
Don't know how the drive bolt on mine got stripped and would not move.
Re: Tail Stock Quill
john lucas
I don't know if your 3520A is exactly like mine or not. The A series has the spindle locking pin underneath the spindle and it's a tapered pin on mine. It fell out a few times until I put it back in with a little more force (bigger hammer). The 3520B had the pin located on the backside of the tailstock and is a threaded bolt. A much better design. On my lathe the 2 won't swap. If yours swaps out then your lathe is different than mine.
I have seen 3 things happen on tailstocks of various brands. The threads strip on the quill feeding bolt or mechanism that drives the quill. The locating pins that keep the quill from rotating get damaged or break (what your problem is I think). I forgot one. The slot this pin rides in can get damaged making it difficult to screw the quill in and out passed those dings. The quill locking mechanism gets jammed or broken. Those are the 4 things I've seen most often and usually only on the less expensive lathes.
Re: Tail Stock Quill
William Duffield
Sorry we didn't get a chance to finish discussing this on the Chat last night.
First, some philosophy: The quill lead screw is the least expensive part of the mechanism, so if anything goes wrong, it should be the part that breaks. Thus, it should be made from the softest steel.
There are a few things that can go wrong causing the failure. John has mentioned some of them.
Forgetting to loosen the locking handle before trying to retract the live center is the most common.
A dirty or galled Morse taper can cause the live center to freeze to the quill. If this happens, then trying to eject it with the quill lead screw and hand wheel instead of a knockout rod can over-stress the threads.
On your new assembly, I think the locking handle rides in a groove in the quill, keeping the quill from turning. If you loosen the handle too far, the quill will rotate. Tightening the handle may be able to gall the cylindrical surface of the quill, making it hard to slide in the tailstock, which also puts more stress on the threads. However, since the quill is more expensive than the parts it interfaces with: the live center taper, the locking knob and the lead screw, I'm guessing it is hardened, so any of the other, less expensive, parts would be damaged instead of the quill. Also, if the quill were damaged, it would damage the tail stock casting itself, which is even more expensive.
Re: Tail Stock Quill
Sam Scalzo
John
The only difference I can see is the slot on mine is on the bottom and the slot on the one I replaced is on the side. I just turned it to the bottom and it works fine.
The only difference are the numbers but I never use them anyway. Thakns for your input. SAM
Re: Tail Stock Quill
john lucas
I should have stated that there are two different ways manufacturers lock the quill from rotating. One is to use a pin that is more or less permanently installed, but can be removed in a pinch. With this method the quill never rotates unless you remove this pin.
The other method is to use the quill lock to screw into a slot in the quill. As mentioned above if you screw it in firmly it locks the quill, screw it out too far and the quill rotates.
3520B Quill Photos, etc.
Doc Green
I have photos of the 3520 B quill mechanism and instructions for taking it apart on my website:
Re: 3520B Quill Photos, etc.
Sam Scalzo
Doc,thanks for the info. I did just what you suggested anmd the threds on the drive rod would not come out. Someone did not take care of it before I got it. I bought it used. I replaced the quill and rod and it works fine. Sam
Re: 3520B Quill Photos, etc.
Cyril Griesbach
Excellent tutorial, Doc. PM owners thank you.
Re: 3520B Quill Photos, etc.
Peter Hyde
I always thought the quill design of my 3250B was inadequate. When drilling using it as a horizontal drill press the only thing resisting the torque from big forstners or spade bits is that little screw which is a loose fit in the groove. I noticed some small burrs were being raised on either edge of the groove and causing the quill to be "sticky". Easy cure was a short piece of suitable key stock with the right sized hole for the screw tip drilled in one side. Now no torque movement at all when drilling and no more "sticky" quill. I don't understand why it's not a standard feature as costs would be absolutely minimal during manufacture.
But on the other side of the equation it's the only complaint I have so compared with other lathes I think I made the right choice😃
Thank you Peter.
Doug Wolf
Quote "When drilling using it as a horizontal drill press the only thing resisting the torque from big forstners or spade bits is that little screw which is a loose fit in the groove. I noticed some small burrs were being raised on either edge of the groove and causing the quill to be "sticky"."
I finally got around to putting piece of 3/16" x 3/16" key stock with the right sized hole for the screw tip drilled in one side in my tailstock after grinding one side off. And now there is no torque movement at all when drilling and no more "sticky" quill. I can't believe the difference when drilling holes with a forstner bit. The quill doesn't drag and I don't have to take it apart to remove the burrs in the groove.
Re: Thank you Peter.
Peter Hyde
Hi Doug,
glad it worked for someone else. Why it's not a standard thing beats me.
