changing a 3520A tailstock quill to a 3520C

[john lucas]

When I was at the AAW symposium in Louisville I was talking to James Green of Powermatic and told him that I had measured the parts from my friends 3520C and though they would fit my A. He called one of the engineers and had them check and they said that they thought it would work. He volunteered to send me the parts if I would do the conversion and write up an article on it if it worked. Why would I want to do that you ask. Well the 3520C has an Acme thread that is 6tpi. It is a beefier square thread so it's much stronger. Since it's 6 instead of roughly 16 advancing the quill is much faster. The job only took me about an hour. If you have patience the slot for the quill pin is easy to cut with a Dremel and small straight cutter. I did have to drill and top a hole for the screw that holds the quill pin. If I can figure out how to put a PDF file on here I will post it. I obviously don't have any info on cost and it may or may not be prohibitive to do this but man what difference it makes when using the tailstock.

 

[James Seyfried]

I wonder if that would work with a 3520B. It already has a quill pin. It would be a nice upgrade depending on the price.

 

[RichColvin]

I am wondering the same thing about the 3520b.

 

[Dean Center]

The original 16 tpi screw is kinda nice for boring. Each turn is 1/16", so you can keep track of how far you've drilled, and it's hard to drill too fast, even with a 1" forstner bit.

However, boring is only an occasional activity for me, and turning the quill out and back in, is a very, very common one, where more speed would be a good time saver. Hmmm.

 

[Ron Solfest]

I have a B as well and the acme threads are a selling point for me, depending on what the price would be…

 

[Alan Weinberg]

beyond my abilities. I’ll just turn it more unless I can borrow you.

 

[john lucas]

I have a B as well and the acme threads are a selling point for me, depending on what the price would be…

Ron get with me. We can measure the parts. I'm guessing since it fits my A series and the C the dimensions of the B is probably identical.

 

[Dave Landers]

However, boring is only an occasional activity for me, and turning the quill out and back in, is a very, very common one, where more speed would be a good time saver. Hmmm.

When you add a motorcycle transmission (or whatever) to your tailstock, post a build-along thread

 

[john lucas]

Dave. I once saw a turner who sold 2 ft diameter spheres. His lathe was a truck rear end using the axle as the spindle. He had a lawn mower transmission for speed and I think ha a 5 horse motor attached to that. He used sharpened lawn mower blades to turn the outside.

 

[Chuck Engstrom]

When I was at the AAW symposium in Louisville I was talking to James Green of Powermatic and told him that I had measured the parts from my friends 3520C and though they would fit my A. He called one of the engineers and had them check and they said that they thought it would work. He volunteered to send me the parts if I would do the conversion and write up an article on it if it worked. Why would I want to do that you ask. Well the 3520C has an Acme thread that is 6tpi. It is a beefier square thread so it's much stronger. Since it's 6 instead of roughly 16 advancing the quill is much faster. The job only took me about an hour. If you have patience the slot for the quill pin is easy to cut with a Dremel and small straight cutter. I did have to drill and top a hole for the screw that holds the quill pin. If I can figure out how to put a PDF file on here I will post it. I obviously don't have any info on cost and it may or may not be prohibitive to do this but man what difference it makes when using the tailstock.

Quill and lead screw (both are needed) together cost about $250. The lead screw is about 1/2, quill the other 2/3. Just bought a set, and they do fit in all versions of the 3520. Quill is 1-3/8 OD, that's the critical measurement. BUT even with Acme threads (a left-handed metric Acme per the manual) excess cranking on the hand-wheel can cause distortion of the threads. Powermatic may need to start hardening these parts.

 

[Ron Solfest]

Thanks @Chuck Engstrom, at that price I don’t think I’ll spring for it given the acme threads don’t sound that much better than what I already have

 

[Saleem Shafi]

@john lucas i stripped the threads on the lead screw of my 3520, and luckily a friend of mine had a 3520a and his quill, lead screw fit my tailstock. i was hoping that meant that your article would mean that the 3520c quill/lead screw would fit my 3520, but the lead screw won't come through the back of the tailstock.

i see a bushing of some kind in the tailstock that holds the lead screw in place, did you have to take that out? if so, how?

 

[john lucas]

The 3520c fits the 3520 perfectly. In my photos there is a small bushing I added to keep the quill from locking up when you crank it all the way back in.

 

[Saleem Shafi]

hello John,

i bought the 3520c quill and lead screw, but they definitely do not fit my 3520. The lead screw is 3/4" and the hole in the back of the tailstock is 1/2". I'll add some picture below to show the difference. For what it's worth, the 3520A that my friend had is setup the same way as my 3520..

is it possible that the brass bushing in the tailstock can be removed? it looks like the original hole might be the right size for the 3520c lead screw.

thanks,
Saleem.

 

[john lucas]

I'm sure it can be removed. Not sure how because ice never seen one. Worse case scenario have a machinist bore it out.

 

[Saleem Shafi]

yeh, will have to do the same the the hand crank, as well..

i'd be curious to see what your old 3520A lead screw looked like.

 

[Dean Center]

Saleem, could your Powermatic be one of the very first 3520 (not A, B, or C)?

 

[Saleem Shafi]

Saleem, could your Powermatic be one of the very first 3520 (not A, B, or C)?

Yes it is. One of the last two out of the US factory, i'm told.

 

[john lucas]

They made several modifications of the 3520 when they made the 3520A. The tool.post lock is different and several other things that I can't remember.