Help getting Powermatic 87 back in service

bobbyf · Sep 29, 2022

Hi Guys,
Long time lurker here but this is my first post. I’ve learned a ton and gotten a lot of good advice over the years using the search engine. I’m hoping you can help me out with a 1967 Powermatic 87 band saw.
It seemed to be in good shape when I bought it, I should have looked harder.
The most interesting issue is the lower wheel. It’s a cast wheel that’s supposed to mount on the transmission output shaft with a keyway and lock screws. The wheel itself was cracked (wish I had seen that!) so had to come off. Turns out that the lock crews were missing and the threads were gone on one side like maybe someone drilled them out. Instead of fixing that, I think they took the transmission apart, turned the shaft, added an oversized bronze bushing and pressed the wheel on. It doesn’t make a lot of sense but the bearing on the output shaft looks newer – maybe they were in it anyway?
I brazed the crack in the wheel. It’s 10-20 thou out of round and won’t fit in my lathe. Is that something to worry about? Also puzzling on how to get it back on the shaft.
The rest of my issues are mostly parts. The tranny has a few gears that are worn to the point of being sharp. I can’t find a reference for the gears anywhere.
I’m still trying to cross reference some bearings etc…
I would appreciate any thoughts on the lower wheel situation and advice on parts sources.

Thanks!!

memphisjed · Sep 29, 2022

.02 runout out is going to make your saw do a bobbing head or/and make for blade breaking- you also need to tension it as blade stretches.

If you have a mill with a rotary you can true it up with that.

wood2steel · Sep 29, 2022

Bobby,
PM me when u get a chance. I have a couple contacts in Tennessee and here in GA that might be able to steer you with the repairs. Have been running Powermatic equipment for 45+ years.
Johnny

bobbyf · Sep 29, 2022

I was worried about that. Unfortunately I don't have a mill that'll take a 20" wheel.

Wood2 - PM sent

Richard King · Sep 29, 2022

You may want to ask this in the Woodworking forum as Powermatic is more of a wood grade machine in my opinion. Also Keith Rucker on You Tube has a show on Band saw rebuild

reggie_obe · Sep 29, 2022

If the saw has value to you, it's not unreasonable to have to have the wheel trued, crowned and balanced by a machine shop. May prove to be cheaper than sourcing another used wheel with its own problems.

bobbyf · Sep 29, 2022

How important do you think balance is? The wheel is drilled in several places from the factory balancing. The crack was only a few inches and actually through one of those drill holes. I used a die grinder to create some space around the crack, brazed it then sanded the brazing down smooth. The difference in balance is just the weight difference between the bronze braze and the iron that it replaced.

TGTool · Sep 29, 2022

bobbyf said:
How important do you think balance is? The wheel is drilled in several places from the factory balancing. The crack was only a few inches and actually through one of those drill holes. I used a die grinder to create some space around the crack, brazed it then sanded the brazing down smooth. The difference in balance is just the weight difference between the bronze braze and the iron that it replaced.

If you have the eccentricity you note, you'll also have a shift in mass. Meaning, essentially, that the current center hole is not actually quite on the centerline used when it was manufactured. The gut sense is that the difference in material weight between cast iron and braze isn't material. Since they balanced it initially from the rough casting, if you were to set it up on a mill, indicate the machined rim surface, then bore and sleeve the hole, you should be back to where it started. More or less.

bobbyf · Sep 29, 2022

TG - I may be confused - or confusing. The wheel was cracked at the outer rim where a spoke tied in. The free side of the rim was raised at the crack and had enough movement that the rubber belt was worn away from the area. I've been a hobby welder for over 40 years but haven't done brazing. I was so concerned that the rim would be raised at the crack that I used too much clamp pressure and the rim now has a slight low spot where the braze is. I don't think I changed the center any -just goobered up the rim. A lathe would be ideal but I suppose a jig and a mill would work like someone suggested. Does this sound right or am I missing something? I can send pictures tomorrow...

jwmelvin · Sep 29, 2022

Fill in with additional braze material and machine/file back to round?

bobbyf · Sep 29, 2022

jwmelvin said:
Fill in with additional braze material and machine/file back to round?

Or epoxy and new tires. It's not warped - just has the one low spot. I thought about a benchtop jig but never had muck luck doing that type of work by hand. If I can find a machine I should be able to true it up.

memphisjed · Sep 29, 2022

Balance at the levels you are thinking about will not make a difference. Low rpm.

richard newman · Sep 29, 2022

If I understand you correctly, the od of the cast iron wheel is .020 low just in the area where you braised,correct? As far as balance, it shouldn't change much, you haven't lost any iron, just filled in the balancing hole, which might just compensate for moving that part of the rim in .020. I think you could just put a new tire on and grind it true and be pretty ok. You might want to contact Wood Workers Tool Works, I think they can vulcanize a new tire on, grind it true, and balance your wheel.

But you should probably resolve the shaft/transmission issue first. You might want to look at the OWWM site https://owwm.org they also cover metalworking machines. One of those guys might even have the parts you need.

And the sister site http://www.vintagemachinery.org/ will have manuals and parts lists for your saw.

Bill D · Sep 29, 2022

I read it as 0.002 out of round. That is no problem. You could grind the tires round after install. I would balance the wheel on a simple axle and knife edges. Drill holes at heavy spots and drill and lead wool fill light sections. A car wheel balancer should be able to do this?
BilL D

bobbyf · Sep 30, 2022

Thanks for all the input. I looked on OWWM (already knew about Vintage) and found some interesting posts. I'll definitely look closely there.
I hadn't thought of truing after vulcanizing - that may well be the answer if the shipping doesn't kill the deal.
So - one more question, I've noticed that Delta and others made a similar saw. I don't absolutely have to change the transmission gears but I'd feel a lot better if I could. If several manufacturers used the same tranny it would broaden my search. Anybody have any knowledge on interchangeability with other saws?

reggie_obe · Oct 1, 2022

SMT gave you some good advice in his post here in the woodworking section.
It's a large rotating part, if i were mine, I'd want it running true and balanced.

Andrew L. · Dec 6, 2022

bobbyf said:
Hi Guys,
Long time lurker here but this is my first post. I’ve learned a ton and gotten a lot of good advice over the years using the search engine. I’m hoping you can help me out with a 1967 Powermatic 87 band saw.
It seemed to be in good shape when I bought it, I should have looked harder.
The most interesting issue is the lower wheel. It’s a cast wheel that’s supposed to mount on the transmission output shaft with a keyway and lock screws. The wheel itself was cracked (wish I had seen that!) so had to come off. Turns out that the lock crews were missing and the threads were gone on one side like maybe someone drilled them out. Instead of fixing that, I think they took the transmission apart, turned the shaft, added an oversized bronze bushing and pressed the wheel on. It doesn’t make a lot of sense but the bearing on the output shaft looks newer – maybe they were in it anyway?
I brazed the crack in the wheel. It’s 10-20 thou out of round and won’t fit in my lathe. Is that something to worry about? Also puzzling on how to get it back on the shaft.
The rest of my issues are mostly parts. The tranny has a few gears that are worn to the point of being sharp. I can’t find a reference for the gears anywhere.
I’m still trying to cross reference some bearings etc…
I would appreciate any thoughts on the lower wheel situation and advice on parts sources.

Thanks!!

Hey Bobby. I don’t know of this would help, but my Powermatic 81 was tipped over with a forklift (not by me). The upper part of the trunnion for the table broke, and the upper bearing housing mounting bracket broke. Other than those two pieces, I am unfortunately going to part out this amazing bandsaw. I have removed all pieces and parts, and thought I would share with everyone here that I am going to sell everything. Upper and lower wheels, doors, table, switch, counterweight assembly, lower trunnion bracket, upper wheel housing bracket, lower wheel bearing housing, full foot brake assembly, motor mount plate, blade bearing assemblies, etc. Get ahold of me before I put these parts on eBay!

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Help getting Powermatic 87 back in service

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