PM90 riser blocks

[Mike Cruz]

Hello. Not sure if this is the best spot for this thread, but I recently acquired a 1981 PM90 lathe. It has a 12" swing over the bed. My understanding is that the PM91 was the same lathe but with riser blocks. I've contacted PM and they no longer have them. They referred me to a company in Atlanta that "may" have them. I called them. They do not, and for the one request a year for them, will not be making/getting any more.

I know that I could probably get them made at a local fabrication shop. But, if they don't know what it is they need to make, I'd have to be quite specific...and I'm not certain that I would know enough what I need to get exactly what I need.

Does anyone know where I could get a set? Or does anyone have a set they are willing to part with? I know it's a long shot, but it is the only thing from keeping this from being my dream lathe.

EDIT: I suppose I should add that I'm talking about risers that add swing capacity, not to make the lathe taller. 😉

Thanks for your time.

 

[glenkey]

http://www.owwm.com/pubs/detail.aspx?id=822
Don't know if this will do you any good or not.
If it were me and I was going to have parts fabricated I'd start by taking the head off and getting measurments and seeing what kind of clearance is needed inside the head. Then ya gotta go to the other end and get the tailstock lifted 😀
Good luck with the project, hope you are able to find what ya need.

 

[Dale Miner]

Mike,

There is more to it than just the riser blocks.

The drive belt will need to be longer. The reeves drive belt is kinda pricey.

The belt guard will need modification to properly mount and guard the belt.

The banjo will be to short to effectively get out to and around bowl blanks.

Unless it is the jack shaft version, the minimum speed is going to be to high for larger bowl blanks.

Having said the above, I have a PM90 and thought about raising the headstock before deciding to get a 3520B.

I have machine shop capability, but thought I would use hard maple for the riser blocks and work them to size with a thickness sander and table saw. A glue up with end grain as the load bearing surfaces would be best for the riser blocks. End grain would resist wear better, and hold the vertical height through weather changes better. If the headstock block was intentionally made a bit low (1/32"?) it could be shimmed up to match the tailstock height, and lowered as the tailstock riser wears, although I would think that with a little care and wax on the ways, wear would be a long time coming.

Later,
Dale M

 

[Rick Crawford]

Mike,
I have considered doing the same modification to my Yates-American J170 lathe, might still do it. The advantage I have with my Yates is that it has already been modified with a DC motor with true variable speed, and uses standard industrial drive belts that are readily available at NAPA. Oneway sells their banjos separately, which will probably take care of that end of the modification...check their website for particulars.

Smiles,
Rick

 

[john lucas]

I did this with plywood blocks on my old J-line lathe. It worked but gave me a little extra vibration. I made tool rests with longer tool posts to solve the tool rest height problem. My lathe didn't have a reeves drive and I had replaced the belt with a link belt so I just added more links. The tailstock locking mechanism took a little more work because in those days I didn't have access to a metal lathe. I don't remember exactly what I did but I'm sure it involved making a longer bolt.

 

[Mike Cruz]

Thanks, all for your replies. Sorry I didn't get back earlier. I was expecting (and I have to be honest, a little disappointed that I hadn't heard anything yet) an email when someone replied. I never got any, and decided to just check in. I suppose I never activated that option...I'll try to get right on it.

As for my set up. The lathe is 3 phase, so I had to either get a convertor, or swap out the motor. I went with a VFD. I also bypassed the START and STOP positions, so they are merely slower speeds now. I can get 336 RPM as my slowest speed, and with the VFD and a pot, I can go down to, well, zero! I also put a digital tach on it. So, the lift is all that is keeping it from being a dream...

glenkey, I haven't gone to your link yet, but will as soon as I'm done writing this. 😉

Dale, yeah, I knew about the belt, but also found out today that PM actually still sells the PM91 belt cover, so I'm set there. I hadn't thought about the banjo not being long enough to get out to a 21" bowl. Good point. Even with tool rests with longer posts, I will/may max out before 21". I'll go take some measurements.

Also, I've had PM email me the manuals for both the PM90 and PM91. The PM91 manual show the configuration of the riser blocks, so I have something to go on.

My plan would be to go steel, not wood. I'm a set it up once kinda guy. I don't want to constantly have to readjust due to the wood wearing down. Also, while my plan is to do the full 4" rise, it is not because I want/need a 21" lathe (hehe, it makes me laugh saying that I dont' want/need it...of course I do 😀 ), it is more because I can get a belt cover that fits without modification. Otherwise, I would probably do a 2" lift. Oh well, guess it'll have to be 4" or nothing... 😉

If anyone else has any thoughts, please chime in.

 

[Dale Miner]

The 90 is a very solid machine, and there is no doubt the bed and headstock could stand the swing.

Go for it, and report back.

Later,
Dale M

 

[waltben]

I don't know about PMs, but I put 2" risers on my Stubby's headstock several years back to gain extra swing for oval turning. The Stubby's motor is in integral part of the headstock, so all I needed to do was have the blocks machined with flat surfaces and holes drilled in the correct spots. Longer bolts from Grainger fasten it down. A friend who is a machinist made screw in extensions to all my tool rests. Only down side is that I can't use the tail stock any more unless I remove the riser blocks, but I hadn't used it for at least three years prior anyway. If I ever need to do long spindle work, I'll probably pick up an extension for my Delta 46-460.

 

[Jim Echter]

I have PM90 Riser blocks, etc. For Sale

Powermatic 90 owners,

I am the proud owner of, what I was told, are the last set of steel riser blocks that were cast for the PM90 before the mold cracked. My plan was to convert my 90 to a 91. I accumulated a second belt guard, pulleys, shaft, longer belt, pillow blocks, etc. over an 8 year period. Long story short, I have over $1000 invested in the project. It is almost everything needed to raise a PM90 to a 20" swing.

I was all about to start the project when I had the opportunity to purchase a newer lathe and sell my PM90 at the same time. I will say, that 90 was a tank and ran smooth as silk. I still miss it and wish I still had it for baluster jobs, etc.

If interested in this "kit", contact me to discuss.

Jim
jim (at) truecreations (dot) biz

 

[Mike Cruz]

Wow, that would have been a great find...if I were still in the market! :mad: I ended up having them made (out of steel) to give me an 18" swing. LOVED that PM90. I did, however, sell it recently. Got a premium for it, and couldn't pass the offer up.

IIRC, those risers (factory to make the PM90 a PM91) gave the lathe a 21" swing, not 20"...but I could be wrong.

If you simply put these risers up for sale, I'm sure you could sell them quite easily. I've heard of a LOT of people that were looking for them over the last few years (while I was searching).

Thanks for the offer. I do appreciate it!