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3520 Live Center ?

M

Mark Warden

Joined
Feb 9, 2009
Messages
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Location
Sinking Spring Pa.
I noticed when I use the live center on my pen mandrel and buffing system it gets pretty hot. Is this normal or am I putting too much pressure on it?
Also does anyone know where to get different screw on tips for it?


Thanks in advance
Mark
 
Mine doesn't get hot under very heavy pressure turning a 19" x 8" deep bowl blank. You should not even remotely approach that kind of pressure turning pens. The speed is fairly low on these. I do turn smaller spindles at close to 3000 rpm with much less pressure on the tailstock and it doesn't heat up when I do that either.
 
Hi Mark,

From the PM live centers I have seen, it looks like a direct knock-off on the Oneway live center. I would bet that you can get some of the different cone tips from Oneway. I know that the Oneway is threaded 3/4-10. They also have a pen turning tip that fits in the end of the live center.

I have abused mine to no end. :) And have never experienced any heating problems. But I am sure that buffing puts a lot of side pressure on the live center.

Best wishes,

Dave
 
Mine gets warm, though not "hot", when running at speeds over 900rpm. I seem to recall the designed induced load tops out at around 500 pounds (??), so I suppose you could exceed that, but I cannot think of why one would need to crank in so much strain from the tailstock. The PM live center is pretty much like the OneWay live center, and while OneWay does sell a point to use for pen turning, I am not sure if it will fit in the PM center. As for the threaded accessories, you can pretty much make what ever you need from wood, brass, aluminum, plastics, and even cast iron or steel if you are careful turning it (I have turned them all on the 3520B with no troubles), etc. The threads are 3/4" x 10 tpi (same as the OneWay), and taps are readily available at Enco, and other machine supply houses. Other than a screw-on adapter to mount a scroll chuck to the live center, and the large and small cones, I do not know of any other commercially available screw-on accessories for it.
 
I do turn pens around 3000 rpms and turned 10 out in a row when I noticed the heat.It's not too hot to touch but it gets very warm.As for buffing I have the Beal 3on and I don't want it slipping in the Morse taper so I do crank it down tight.I'll try the oneway tips I just don't want to wreck the point on the center using these attachments. Thanks for the input.
 
I don't turn pens, but I just ordered two live centers from Osolnik Machinery - YESTERDAY because I noticed that my live center was warming up...
It might never seize, but I'm not going to have it happen and not have a good backup. Joe has them on "closeout."
Mine ship today, they should hold me for another decade, so you folks can have whatever are left :)
 
I recently had a live center that started to get warm, then it started getting hot, and it was not long before it became a dead center in every sense of the word.

As far as tailstock pressure goes for pen mandrels, it should be almost nothing. The way that I judge it is as follows: set the tailstock so that it does not quite touch the mandrel and then with the lathe running at a low speed, gradually advance the live center until it begins to turn. Apply very light finger pressure and see if the live center stops -- if so, advance the live center just a tiny amount and verify that very light finger pressure does not stop it from turning. Stop right there -- that is all the pressure that you should be using. If you apply too much pressure it will cause the mandrel rod to flex and the result is that the pen can't be turned round -- instead it will have an egg shape cross section or worse, it might look like chatter work.

During set up, you also need to insure that the mandrel rod is perfectly straight -- if it isn't, fix that before proceeding or you will never to smoothly turn a pen without lot of unnecessary sanding.
 
when I first got my 3520 the live center got so hot, it started to smoke.
I called Powermatic and they sent me a replacement and said keep the old.

So I dissembled it and found that it was not milled cleanly in the bottom, the part that contains the bearings closest to the MT.

the bearing turned with no resistance without load but under load the shaft would just touch the casing and heat up.

I cleaned up the the high spot and now have two (smoke free) live centers.
 
3520 Live Center

I have both the Powermatic and Oneway Live Center I use the oneway pen mandrel point on both. Neither gets warm that I have noticed on my 3520 or Jet 1220. I would let Powermatic know as it should not get warm doing pens unless you really over crank the tailstock, but at this point you should be getting flex in your mandrel and know it's to tight. I've had problems in the past getting the center point out of the Powermatic live center so if you do get the point from oneway and have a problem with the center point get a long drift pin and a big hammer. Make sure you put it in the vise correctly as you don't want to put pressure on the bearings.
Bill D. :cool2:
 
Mark if you are turning pens you should have a 60 deg live center. The stock powermatic is not 60 deg and is a ligher metal, maybe even aluminum. If it works I am not telling you to change, however I bought a 60 deg from an on line place and it is wonderful you don't need as much pressure and the mandural just feels more solid.
 
I contacted powermatic service and they told me it is normal for it to get pretty warm so i'll just keep using it and see what happens.Oneway make a tip just for pen mandrels that I will be getting asap.Thanks again for the replies.
 
Mark I turned long and hard with mine this last weekend and it does get warm but I wouldn't call it hot. I can hold it in my hand and it's quite warm. My Nova Chuck on the other hand is much older and when I do the same thing it's just mildly warm.
Hope that helps.
 
I too was comparing it to my old generic center that I never noticed getting as nearly as warm so compared to that I conidered it hot.The guy from powermatic said if I can hold it it's fine.Maybe I just didn't care enough about the $12 stock center to notice :) thanks for the reply.
 
Replace the bearings

Brearings in live centers can be replaced by any authorized PM repair center/company. I have had mine done, 2x since the first set were not "all square". No big task and minimum $$. Philip
 
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