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PM 3520A Bearings

Cutting Crew

Cutting Crew

Joined
Feb 24, 2005
Messages
18
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Location
Derbyshire, UK
Hello all,

I've recently noticed play in the bearings on my 6 month old PM 3520A, is there any adjustments that can be done or do the bearings need replacing after such a short time?

This is one of the few Powermatics in the UK so there's no one over here to check with as to the bearing condition on other PM3520s.

Regards....Mike
 
No they should not need replacing, unless you turn about 20 hours per day. 🙂 Seriously though, that should be covered under warranty, unless you bought it used from someone. Do you feel comfortable replacing them yourself?
 
I have a lot of friends with 3520's and 3520a's and don't know of any of them having bearing problems. Most are fairly old. Mine is a year old and has quite a few miles on it with no problems. I'll look tomorrow and see if I can find any adjustments. I have to work until 11pm tonight so you can bet I won't look then.
 
Cutting Crew said:
Hello all,

I've recently noticed play in the bearings on my 6 month old PM 3520A, is there any adjustments that can be done or do the bearings need replacing after such a short time?

This is one of the few Powermatics in the UK so there's no one over here to check with as to the bearing condition on other PM3520s.

Regards....Mike
Click to expand...

Mike,

Would be good if you define "play." Do you mean the spindle has lateral movement at 90* to the shaft's axis? Do you mean in/out movement as in line with the axis of the spindle? Have yo measured the play with a dial indicator?

The front spindle bearing may need a bit of tightening on the pre-loader castled nut if your machine uses such. Been a long time since I looked under a 3520 hood, so I don't remember if that is the case.

You should also e-mail PM tech support.

M

ps: Just looked up a 3520 schematic

http://power.forest.net/wmhtool/PMWood/Manuals/CurrentManuals/3520A-M-0460221.pdf

and it shows both a bearing castle nut (HS part #s 14 & 15) on the handwheel end of the spindle plus a bearing retention collar and set screw (HS parts 64 & 65) on the arbor end. Either of those may have worked in a bit of slack that will allow the bearings to not sit tight in the headstock casting and give some "play" in either direction.

M
 
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Hi all,

Thanks for the help, I do use the lathe quite a lot as I'm a full time gallery turner, so it does get a fair bit of use.

As regards the play, with a chuck mounted I can feel some lateral movement in the bearings, I haven't looked at the rear end of the spindle as yet to see if it can be adjusted and as it's getting on for midnight over here that can keep till the morning.

Any help or advice with the adjustment of the bearing lock nut would be most welcome

Thanks again for the help.

Regards....Mike
 
Cutting Crew said:
Hi all,

Thanks for the help, I do use the lathe quite a lot as I'm a full time gallery turner, so it does get a fair bit of use.

As regards the play, with a chuck mounted I can feel some lateral movement in the bearings, I haven't looked at the rear end of the spindle as yet to see if it can be adjusted and as it's getting on for midnight over here that can keep till the morning.

Any help or advice with the adjustment of the bearing lock nut would be most welcome

Thanks again for the help.

Regards....Mike
Click to expand...

Good Morning Mike,

Can't help you on as to what the adjustment should be as I've never done that on your machine. Think you'd best e-mail PM directly for the "how to" info. However, since you mentioned you had a chuck mounted, before you go further, I think you need to verify that the play is in the spindle and not your chuck. So,

1. Remove the chuck, grasp the spindle and try to move it side-to-side in several directions. You should be able to feel, even hear slight lateral play in the bearing/spindle/casting assembly. You can use your live center inserted in the headstock's taper to give a bit more leverage, but make sure that the tapers are clean and that it's seated tightly or it will wobble in the taper. You can spin on a faceplate for a better grip as well.

2. Remount your chuck and make sure that the thread adapter is seating tightly against the spindle's shoulder at the back end of the threaded section. If that's not happening, chances are the play you're getting is in the threads because the chuck adapter is not tight. This can happan if a chuck's thread adapter is not cut with sufficient thread relief to allow the collar ring to seat properly. If the chuck doesn't seat tight to the spindle's shoulder, your solution will be to have a machine shop extend the thread relief a bit deeper into the adapter. The temptation is just to use a washer, but they're not uniform in thickness and will throw off alignment of the chuck so don't.

3. If you couldn't feel play in the bare spindle, and if the chuck adapter is seating tightly on the spindle's shoulder, you need to check how well the adapter is seated in the body of the chuck. If the adapter has loosened (as it may with reverse turning operations) even a fraction, that's likely your source and your solution will be to reset it. I use a bit (NOT much) of thread lock compound on my adapter threads inside the chuck which, in addition to the grub screw, keeps things tight.

Chances are, PM will ask you about 1, 2, and 3 anyway, so you might as well do them before you contact Tech Support. They're trained to blame the problem on stuff other than their own parts, but you'll be able to say "Done That" and get them in the mood to send you new parts. 😀

Mark
 
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I have over 2,000 hours on my PM3520a (maybe over 3,000 hours). A few months ago I noticed a very minor amount of play. I do mean minor. I was able to just barely move the shaft and detect that movement. It was almost undetectable, but it bothered me.

I discussed this with WMH (Powermatic) at the AAW symposium. The procedure to fix it is simple. And they handed out DVDs at the symposium which included the procedure as well as info on the 3520b.

The motor-side of the shaft has a castellated nut on it (aka castle nut). The detents in that retainer can be loosened with a screwdriver. Note the position of the nut before you do this. They suggested just barely tightening the nut so that one of the fingers on the castle nut lined up with a slot. Using this procedure you will find that one of the castle nut's fingers probably lines up with a different slot.

The amount of castle nut turn was about 1/8"-1/4" of a turn on the nut on my machine. Note that is not 1/8 of a turn, but 1/8 inches - 1/4 inches. I just barely moved the nut. That fixed it on my machine. If you tighten it too much it will overload the bearing. The symptoms of an overloaded bearing is that it will get real hot. And it will fail early. You might want to do a day of turning, and feel the bearing. Then do the tightening procedure. That way you have a sense of how warm the bearing normally runs.

I agree with Tangboy5000 that you should not have to replace your bearings unless you have a huge number of hours on the machine. You can probably just tighten the bearings to resolve the issue. Let me know if this wasn't clear or if you have more questions. Also I'll be interest in hearing if this resolve the problem or not. Thanks.
 
Hi all,

Thanks again for the advice and Jeff for the "How To".

I tightened the castle nut and it stopped the movement but I had to turn the nut further than I expected to stop the lateral play.

I have a load of work to do tomorrow so I'll keep checking the bearings and see how they feel as I'm going on.

Regards....Mike
 
It's possible that your bearings could wear faster than mine based on the type of turning you do. It's also probable that you also have a lot of hours on your machine.

Sorry I didn't respond earlier. I've recently gone to work at a PC company startup and they are getting the hours out of me. 🙂
 
Hello All,

It's a good week or so since I last posted about the bearing problem with the 3520A, I tightened the castle nut until the lateral movement disapeared and at the time I mentioned I had to turn the nut further that I was expecting.

I did some turning the next morning and noticed the spindle was getting warm so I asked further questions and someone suggested the bearings could be a poor fit in the housings. When I removed the bearings initially the front bearing did come out very easily.

Since then I have again replaced both bearings this time using a liqued sealant around the outside of both bearings, this tiny drop of liqued seems to have done the trick. Now as I tighten the lock nut onto the spindle with just finger pressure the end movement is gone and, more importantly I can feel no lateral movement either. It would appear the original bearings were OK but they were badly fitted into the housing.

Thanks all for the help and advice offered, hopefully, now I can get back to work and start on the pile of timber waiting for me.

You can't help me with car problems can you? I've had a Vauxhall car (GM Group I think) on order for almost 6 months and all the company do is keep putting the delivery date back and back, they're having problems with supplies for the assembly line in Belgium. Still my lathes working and I suppose I can't have everything.

Kind regards....Mike
 
That's great news Mike. I'm glad you were able to get the bearing problem resolved. It's interesting that they didn't seem to seat very well.

I don't know what a Vauxhall car is, but it can't be worth the wait. There are plenty of cars in most dealers' inventories.....why wait for one?
 
Mike,

I wonder if a part may be missing. Often, the outer recess for a bearing will be slightly oversized on purpose to facilitate installation and removal of the bearing. In order to remove the free play, a special type of corrugated cylindrical shim is fitted into the space between the recess and the bearing. This arrangement also compensates for misalignment error and concentricity error. Just a thought.

Bill
 
Jeff,

A Vauxhall is/was a British car. Were you forgetting where he is?🙂 From what I've heard, generally in the UK and most of Europe, the dealer orders a car for you, as the don't carry much inventory on their lot, just demo's.

JimQ
 
Hello Jim,

That's true, most of the dealers, whatever the make carry very few cars as stock, just the ones they have for demonstrating.

When they get an order for a particular model they then order it from the factory which normally takes 4 to 8 weeks in most cases.

Regards....Mike
 
Mike, We, on the west wide of the pond, are mostly used to going in to the dealer and saying, "I'll take this one." Then driving it off of the lot an hour later. The car companies found that they were 3 times as likely to make the sale on a right now basis, than an order for later delivery. Unless there was something special needed.

JimQ
 
Hi Jim,

That sounds like bliss, mostly we go into a showroom, take a test drive and place an order. The car I ordered should have been delivered inside 8 weeks, the way things are going I will be lucky if I get it in 6 months.

The plant the SRi models of the Vauxhall are made at in Belgium has problems, one of their suppliers of the body kit parts has failed to deliver and production of the and one or two other models has stopped.

On a better note, the bearings are working just fine now, in the last few days I've turned 3 large hollow forms, no bearing noise and no warm spindle. The liqued around the outside of the bearings did the trick.

Regards....Mike
 
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Duh?

Cutting Crew said:
The liqued around the outside of the bearings did the trick.
Click to expand...

Mike,

I assume it's a British term, but I just have to ask, what is "liqued"? I can equate to "liquid," "licked" or "lacque[re]d," none of which make any sense in your sentence.

Mark
 
Mark,

The liqued should have had a capital "L" (Liqued) it's the trade name of a bearing lock used over here that I bought with the second set of bearings.

It's neither a liquid or a paste but a gooey type substance that takes up any minute play between the bearing and the housing. The sealant sets hard in a few hours so I was advised to use it scarefully and not to get any inside the bearing.

When the bearings first came out of the headstock there was no fit at all, I had been told the bearings should be a good push fit into the housing, the smaller bearing at the handwheel end was a good fit but on the front there was none at all.

Regards....Mike
 
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