Refurbishing a Powermatic 3520b

[ted sherman]

Yesterday I purchase a Powermatic 3520b, but without the motor and all electronics (switches, cables, control panels, etc), for $400. It’s got the headstock, bed, tailstock. The spindle turns smoothly and the pulleys look good. The electronics were damaged/destroyed from a fire in the other side of the guy’s shop. yea, I know, I could have been suckered, but anyway. The bed is flat, the spindle turns freely and smoothly.
I couldn’t find a discussion here regarding rebuilding a Powermatic, but if there is one could someone point me to it. Or, if any of you Powermatic folks have had to do so or know someone who has, I would love for you to contact me. If not, do any of you have recommendations for non-manufacturer parts and/or where I can get them? Or do any of you have 3520b parts that you’re willing to sell?

I’m okay with electrical, but no genius at it, though I can follow a wiring diagram and easily connect wires. I much prefer wood! I talked to Powermatic yesterday morning and the tech guy there thought I could probably replace all the “innards” (my term) for $1200-1500. Part of me says go all original manufacturer parts, but the other part says save $. Also, I’ve heard/read problems about the OEM Delta inverter—that it trips and/or fries rather easily.

If you weren't going to put in OEM parts, what would you recommend for motor and inverter? I've found Hitachi inverters for under $300--Powermatic wants over $600 and I've heard those Delta inverters have some problems. PM's website says something like $575 for motor but the tech guy I spoke with said under $500. I've got one guy willing to sell me a new motor, signal cord, safety on-off switch, and potentiometer for $500.
I’m open to any/all advice and suggestions. Feel free to contact me privately tedsherman@me.com.
Thanks,

[Don Jarvie]

There's a forum PM 3520 Tips dedicated to the lathe. Even buying what you need from PM your still way ahead of the game. Used 3520s run 2500 plus.

[Jim Underwood]

There's a forum PM 3520 Tips dedicated to the lathe. Even buying what you need from PM your still way ahead of the game. Used 3520s run 2500 plus.

To clarify, the forum name is: "PM 3520 Tips" ?
I wish I'd known about it when the motor on my Jet 1642 died. They use essentially the same motor with a different shaft configuration. From what I can tell, it's nearly impossible to find an aftermarket motor for these things....

[ted sherman]

Thanks. That forum has migrated here: https://docs.google.com/document/d/1...hVIyVJ4oc/edit

[Dennis Ford]

You can get inverters from a number of suppliers, Hitachi is one of the best and much less expensive than from Powermatic. The motor will be difficult to find except from Powermatic, it has a longer than standard shaft.

[Brice Rogers]

Dennis F., your post has me curious. How much longer is the shaft? I think that it would be possible to use a specialty coupling or a custom machined coupling.

I made a specialty coupling (extending a shaft) to allow me to use tool rests from a 9" lathe on a 22" lathe.

[Geoff Crimmins]

If the fire caused that much damage you might want to replace the spindle bearings while everything is apart. I don't imagine the heat did anything good to the seals or grease in them. You'll likely have to go with the OEM motor and motor pulley because I doubt you'll find anything else that fits. You could call someplace like Factorymation and they could help you select a VFD that would work well. The forward-reverse switch and speed-control pot and knob could be purchased from an electronics supplier or even Radio Shack if they still exist. You can buy various on-off buttons from Grizzly, but I don't know if they have one that would fit. I have no idea about the tachometer sensor and LED display; you might have to go OEM with those as well.

--Geoff

[ted sherman]

I've got two hits on two 3520b motors, one new, one rebuilt, so that won't be a problem. I've found the Hitachi vfd and the DocGreen site has instructions on installation and programming it for a PM motor, so that's very helpful. Now, it's just buying all the stuff. Thanks all.

[ted sherman]

Yeah, I probably will replace them. I'm trying to get the quill/lead screw out of the tailstock--they are frozen. I'm hoping not because of the fire. I've tried using a block of wood against the end of the lead screw and hitting that with a hammer, but it hasn't budged. Any suggestions?

[John K Jordan]

Yeah, I probably will replace them. I'm trying to get the quill/lead screw out of the tailstock--they are frozen. I'm hoping not because of the fire. I've tried using a block of wood against the end of the lead screw and hitting that with a hammer, but it hasn't budged. Any suggestions?

Assuming you checked that the quill locking lever is loosened and that the setscrew on the back side is not jammed: if any parts are warped by the heat they might need to be replaced. Does the screw turn? Sometimes a lot of heat will cause oxidation and lock up things. I've had some success in unlocking stubborn parts by soaking in PB Blaster for a few days, occasionally tapping with a hammer on the outside to make "ringing" vibrations. I buy it by the gallon PB Blaster and submerge the parts. I've soaked in WD-40 also but I like the PB Blaster better.

If locked because the metal is warped or galled I would next try a hydraulic press for something that was normally supposed to slide straight out. You have to be careful that everything is aligned and supported properly or you can severely damage parts with a press - sometimes this required fabricating a jig. I have a 20 ton press (perfect for farm equipment maintenance and repair.)

You might also ask this on the other forum where you first posted before you bought it. Some people there are quite experienced with the PM lathes and various issues.

JKJ

[Bob Behling]

the belt on 3520 is by Gates. Can be be purchsed from Motion Industries for approx $20.00 Price quoted 2 yrs ago vs $94.00 @ PM

[ted sherman]

Thanks, John. I guess I'll try the PB Blaster (is that the name I'd find it by?). I'll put the handwheel back on, but I don't think the screw turned at all. I've thought about the hydraulic press, and that's what I'm afraid I'll have to do. I wonder if Harbor Freight or Northern Tools would let me "try" one of their presses? I don't have one and don't know anyone who does. I'll also ask on the Facebook Woodturning Exchange forum.

[ted sherman]

Thanks, Bob. It's actually got the belt. I do have to get the bottom sheave/pulley for the motor spindle though.

[John K Jordan]

Thanks, John. I guess I'll try the PB Blaster (is that the name I'd find it by?). I'll put the handwheel back on, but I don't think the screw turned at all. I've thought about the hydraulic press, and that's what I'm afraid I'll have to do. I wonder if Harbor Freight or Northern Tools would let me "try" one of their presses? I don't have one and don't know anyone who does. I'll also ask on the Facebook Woodturning Exchange forum.

https://www.amazon.com/Blaster-16-PB.../dp/B000I2079E
I buy it (and WD-40) by the gallon from an auto parts store.

This might sound odd for something damaged by fire but you can also use heat and cold to break loose parts. Muffler/frame guys sometimes call an acetylene torch a "fire wrench". A press is invaluable if you often fabricate or repair things but otherwise probably not worth the expense otherwise. I've seen them for $100 on Craigslist. It may be better to take the tailstock to a good equipment repair shop where they have the tools and experience and ask them pretty please and give them your wallet. I'll bet the local bobcat shop could get it apart quickly.

JKJ

[Bob Bouis]

I can't remember offhand how the tailstock is set up, but my favorite tool for getting stuck things unstuck is an air hammer. Spray it with pb blaster, then hit with the air hammer a little. Wait 20 minutes and do it again. If it still doesn't come unstuck, repeat the pb blaster until it does. Just make sure you use a non-destructive bit.

If you don't have one (but do have a compressor), they can be had for $10 at harbor freight or the like.