Powermatic 90 questions

[Lee Alkureishi]

Hi all,

So, my PM90 clean-up / tear-down is now underway, albeit slowly. When I bought it, I was aware that it made a little more noise and vibration than is ideal. Over the last couple of weekends, I hooked up and mounted the VFD and control box. Finally got everything working last night. Now, it's time to figure out the source of the noise :)

I took the belt cover off, and removed the v-belt. It's a wider one than I'm used to - anyone know the size or type of this for replacements? Or, can I use a regular 1/2" red link belt in it's place?

Once I had the belt off, I played with the reeves drive sheaves. On the spindle pulley, the movable portion of the sheave (sheaf?) has about 0.5-1cm of play around the circumference of the spindle - I can rotate it a small amount by hand with the spindle fixed. Doing so recreates the same "clunking" sound I get when the lathe is running.

Is this small amount of play normal, or would it potentially account for the clunking/vibration I'm getting? Any idea how to fix it? I'm guessing I need to take the headstock cover off, and there'll be a setscrew to tighten or similar, but haven't yet figured out what to unbolt to get access to it :)

I know that spindle bearing replacements are also in my imminent future, but I'll need to save my pennies before I can make that happen. I'm not sure the bearings are the source of the problem, though - spinning the spindle manually with the belt removed is smooth and silent.

Are there other bearings in the headstock that will likely need replaced? I've read something about v/s roller and v/s roller bearings, but I'm not sure exactly what they are or whether to tell if they need replaced.

Thanks in advance, sorry for the multiple questions,

Lee

[Mike Cruz]

Hi, Lee. If the belt you are referring to is from the motor to a jack shaft, yes, you can use a linkbelt. If it is direct drive from the motor to the spindle, no, you can't use it. There are a number of sources for your belt. Belts4less is one, but you really do want a quality one without kinks etc.

I don't believe there should be any play in the pulley. Have you tightened down the set screw(s)?

There are two major bearings in the headstock. One at each end of the spindle. There is a grease "seal" between them that you will likely ruin when you take it all apart. If I were you, I'd order 3 or 4 of them. You will inevitably have to take it back apart at least once, and you ruin the seal each time. They are litterally a couple bucks each, so well worth not having a cow when you ruin one (or put it on backwards, or realize right after putting it on that you forgot the previous step, or, or, or...DAMHIKT) or having to pay the shipping (more than the seal) to get another.

The v/s roller bearing is a bearing inside the variable speed control (the handle that you move to change speeds). It rides along a "groove" of sorts on the VS controller. I didn't have to change mine, so you may or may not have to.

[Lee Alkureishi]

Hi Mike,

Thanks for the reply. I found the model of the belt (goes from motor directly to the spindle), and have ordered a couple of replacements, thanks.

There is no set-screw I can find on the inner sheave of the upper reeve's pulley - see the pictures. Unless the set-screw is inside the headstock? In which case, how do I get in there? It seems like a solid piece of cast iron...

Here are a few pics of what I'm seeing. Having played with it a bit more, I believe the play is in the outboard-side bearing - would that make sense? The pictures show the amount of play (in a clock-face orientation - there's no fore-aft or up/down/side play at all).

With the spindle locked, it's possible to move the sheave (with the blue tape attached) about 2-3 degrees. Not sure how much of a problem it is, but wondering whether it's the source of the vibration.

There's also some fore-aft play in the motor arbor - maybe 5mm or so. With the belt off, and the motor running, there's a very small amount of vibration - just detectable that the machine's running. With the belt on and the spindle turning, the vibration level goes up by a lot.

Also, is there any way to tell the model of the outboard-side bearing without taking the reeves mechanism off? I'd rather just tear this down once, with new bearings in hand, if at all possible!

Thanks again,

Lee

[Mike Cruz]

Well, since mine has the jackshaft, I'm not sure if anything else is different, but I do have an idea... You don't have to take the entire thing apart, but you may have to do a little disassembly/assembly... IIRC, you are correct that there is no set screw for the inner 1/2 of the upper pulley. There is, however, again IIRC a keyway (like on a motor shaft) for that pulley on the spindle. So, take off the outter ring. Take off the outter 1/2 of the pulley, and then pulle off the inner 1/2 of the pulley. These ought to all come off without incident (hahahahahahahaha, hehehehehehehe, hohohohohohoho...I kill myself...without incident...yeah right!) What I found best to get them off (if/when they refuse) is to heat the pulley with a hairdrier or heat gun...trying not to heat up the spindle, too, to expand them ever so slightly to get them off. I have a sneaking suspicion that someone pulled them off before and forgot to replace the key/lost it/whatever. NOTE: The key has a pin, so it lifts out...straight up. Try that, to see if you get anywhere with that.

IIRC, the outboard bearing is not all that difficult to replace. The inboard one is a little trickier. It would help to either have the right tools and know how, or just take it to a metal shop and say here are the new bearings and shaft...please replace them. They would have both! ;)

BTW, that's a sharp looking machine you've got there, and I'm envious of you gapless bed...

[Jon Prouty]

Lee, before going to the trouble of taking it all apart, does your belt have a memory to it? When it is off, and laying on the ground, does it form a circle or an oval? If oval, I would try a new belt before digging into the lathe too far.

Just a thought form a guy that does not have a lathe like this.

Jon

[Lee Alkureishi]

Thanks for the tips - I changed out the belt, but the noise is still there.

I tested the lathe with some scrap wood last night - it's very nice. There IS some knocking and vibration, but it doesn't seem to transmit to the workpiece - I can get a very nice finish on it without too much trouble. I love the motor - the 1hp 3 phase motor has tonnes of torque, even with the VFD at 20hz - I can't slow it down, let alone stall it. At 60hz, I was able to take a cut the entire width of my 14mm carbide cutter in a damp piece of river birch, and the motor didn't even hesitate.

I do plan to still replace the bearings, as soon as I can get some time off on a weekday. One additional question though:

Any idea how to get a stuck faceplate off the spindle? :(

It's not rusted on - I actually just put it on there last night. When I was done testing it (no catches), I couldn't spin it back off. I even clamped a large c-clamp to use for leverage, but no joy. The spindle lock holds it locked, but I can't budge the faceplate.

I sprayed some penetrating oil on it and left it overnight, and plan to go buy the biggest pipe wrench I can find tonight... But, any other ideas for this would be much appreciated!

Thanks,

Lee

[Mike Cruz]

WIth the spindle lock engaged, it should free up...So, not sure what to tell ya.