Help with grinder rebuild

[KF5LCH]

All, my trusted Buffalo bench grinder is sounding a little rough. I believe it's the right side bearing fixing to go. It has that typical bad bearing sound. The grinder still runs fine, has full power but makes a hell of a racket on the stone side.

A little history on this machine. My dad bought this grinder sometime around 1982 from our neighbor at the time. I can remember watching dad sharpen mower blades when I was just a kid, being totally amazed at the sparks flying from it. It is a Taiwan grinder, but it is still very strong. It has served my family well for three decades. I would love to know how many hours are on this machine. Trust me, it's a bunch.

Can you guys that have rebuilt these machines give me some pointers please? A couple of internet searches yielded next to nothing. I figure the sides of the housing pull apart & the guts come out all in one piece or what? Im just going to replace the bearings & clean it up, that's all it needs.

 

[KF5LCH]

Flippin pics wont resize.

Sorry about the huge pics guys.

 

[Southern]

I've rebuilt several, I'll give you a quick rundown to start, and you can ask me any specific questions you would like.

I've gone into some detail about this a few times before. Read up on my post here to give you some decent visuals to what I'm about to explain. There's a bunch of handy pictures:

http://www.garagejournal.com/forum/showpost.php?p=2663479&postcount=114

First thing you'll do is take the stone guard and both of the wheels off. Keep in mind the wire wheel's arbor nut turns the wrong direction, so righty-loosey on that one. Once you get both of the wheels off, you'll be able to see 4 screws on each side inside the "ear" of the body (right behind the wheels were the arbor enters the grinder). Take those out. What should come out is a thin metal disk and a foam bushing. Since it's a taiwan grinder, you'll probably see a bearing shield too, a thin piece of wobbly looking blue steel.

Once you get all of the goodies out of both sides sufficiently to see the bearings, it's time to take the body apart. Undo the 4 bolts there around the center of the body. Slise them all the way out, and lightly pry the body apart. You may need to use a flat blade driver in the seam.

What you'll have then is the two conical iron body pieces from each side, and the center cylinder with the Buffalo label on it. Inside of the center cylinder is the stator, a big round circle of metal with a ton of wires all the way around. Inside of the stator is the armature, a metal barrel that fits inside the stator almost perfectly. Running through the center of the armature is the arbor (or spindle) the metal rod that is threaded on both ends and has some propeller lookin' fins and the bearings chillin' on it on either side. The arbor and armature actually come completely out of the stator, but that won't be necessary for this rebuild if you only want to replace the bearings (replace both not just one). Just leave everything as is and work on the bearings.

Now the easy part, mark the arbor on the back side of each bearing so you know where it goes again. Take the bearing off with a puller, get the same bearing from your local bearing supply. Don't get chinese ****. Get a german made ***, a japanese bearing of any brand, or an Argentinean made SKF, prioritizing in that order.

Start here and report back to me with more pictures if you have any issues or problems. Don't force anything, all grinders are very different, so you may have an electric brake, grounding switch, or any number of things connected to the inside of one of the ears. The bearings might be designed to come off with the ears (with a plate behind them to keep them attached to the body). There's a mass of variables here. Start by getting the guards, wheels, and bearing shields off, and go from there. I'll be here to assist if you get stuck.

 

[larryq]

Tremendous description of a grinder rebuild-- we're indebted to you Southern.

 

[2oolhound]

Your grinder looks identical to mine here (also taiwan from same era). Mine had an induction type starter on it which you have to have a certain distance from the windings so be careful to mark it's position on the shaft during dis-assembly. See photos on post #19 here:

http://www.garagejournal.com/forum/showthread.php?t=102368&highlight=grinder

 

[KF5LCH]

Thanks for the help guys. I was too busy with the holidays this past weekend to start on it, but I plan on getting started this weekend. Southern, I appreciate the write up.

2oolhound, that looks alot like mine. Yours looks like it might be a little bit older than mine.

Be patient guys, I'm gonna need your help for sure.

 

[KF5LCH]

Back from the dead. I figured I would add to this thread vs. starting a new one. Fast forward a year.

I red tagged my trusted Buffalo & have been using my smaller POS Wal-Mart Black & Decker grinder for over a year. I can't stand it anymore. I need my old Buffalo back in service. On with the rebuild! This will be a simple clean up & bearing replacement. I'm going to post quite a few pics guys, enjoy.

Got the case apart with a flat screwdriver. It came apart, but was pretty stubborn. Took the centrifugal switch off & pulled the armature . Looks pretty chewed up to me, but it still runs like a champ & has twice the power of my B&D grinder




After a quick clean up. I used a pencil eraser. PITA.



Stator is fairly clean. I was actually surprised at how nice it still looked. Keep in mind this machine is at least 31 years old & has seen daily use.





What would be the best method for cleaning the gunk & grime out of the stator & windings? I thought about using some contact cleaner & wiping it out with a rag.

 

[KF5LCH]

Here are the trouble makers. They're shot. I'm amazed they hadn't locked up by now. One is so rough you can barely turn it by finger, the other isn't far behind. The spindle is fine, they weren't to the point of seizing.

The bearings are NTN 6202Z's. Still available & quite common it appears. Thank God.




One quick question, how do these come out? I know I'll need a puller, but it's pretty tight in there. I don't have a puller that will fit. Any recommendations?

That's all for now guys. Thanks for looking. If this refurb goes well, I might try to locate an old C-man block grinder & do a full resto on it. So far everything has went smoother than I thought it would.

 

[2oolhound]

You should be able to find a socket the right diameter to catch the bearing from the other side and use it as a drift to tap the bearing through. If you can't see the bearing from the opposite side you can heat the case up in the oven for 10 minutes (225'), place ice on the bearings and then slap the case down hard on a piece of wood till the bearing drops out. (wait till the wife is out and make sure you have ice although I've used a torch to heat the local area and had the bearings just fall out, no ice needed)

That is one clean grinder! The centrifical switch is positively mounted in position so there is no screwing up it's position on re-assembly.

 

[lilredex]

Place a socket in there that fits that outer race, then wind it out into a larger socket, with a bolt or threaded rod. It will come right out. Put the new ones back in the same way.

 

[KF5LCH]

Here's the other end. I might try the heat & ice method. Not a lot of room to work with.




New bearings are ordered & should be here sometime this week.

I'll be glad to get this grinder back in service. It's been a great machine.

 

[rsanter]

Before heat and ice, just take a socket that will fit into the hole and catch the edge of inner race and give some gentile taps with a hammer. That may be all you need to knock the bearings out.
On the new bearing you want to only put force on the outer part of the bearing so you do not damage it

Bob

 

[KF5LCH]

OK. Got the old bearings out. They were pretty easy. I used a deep socket on the backside to knock them out. 3 good taps & they fell out. My new bearings arrived safe & sound. I had a few projects pop up this last weekend & get in the way of the grinder rebuild, but I did manage to get it cleaned up. I also lucked out on paint. The Rustoleum Hammered finish Dark Bronze is a perfect match of the original!

I wanted to ask advice on how to install the new bearings. The housing is very tight. It's just cheap cast aluminum & I'm afraid if I try to drive them in I might crack it.

The hot & cold method: I just heat up the case in the shop oven to 225 & let them cook for 10 min or so, but what about the bearings? Do I just drop them in the deep freeze overnight?





I think I'll try the hot & cold method first. I'm quite leery of driving them in with a socket. They're REALLY tight.

 

[sasquatch12]

Most definetly heat the grinder housing, and yes put the bearings in the freezer, then work quickly but carefully, do not force things.

 

[454ragtop]

Before you heat up the housing, find a socket, probably 1/2' drive, that just barely slides in the bearing hole. You can use it to help pop the bearings in, don't want to be looking for one and letting the bearing and housing acclimate to the same temp while you look. The bearing bore in that end bell does look awful thin, so be careful.
Jim

 

[3shftmaint]

Press bearings on shaft instead of housing

 

[KF5LCH]

Well, I'm just about to finish up this rebuild. I got the grinder all buttoned up last night. The reassembly was pretty easy overall.

To get the bearings back in, I put the ends of the grinder in the oven at 225 for about a half hour. I put the bearings in my deep freezer overnight. They went in with 2 good taps of the rubber mallet. Very simple.

I put a new power cord on it & gave it a nice new coat of paint. I'm going to pick up a new wire wheel & a new stone for it this evening. I'm stoked at how it turned out. Looks like new & hasn't ran this smooth in years!

I ran it for 20 min last night with no wheels on it to make sure everything was ok. It purred like a kitten. It's so quiet with the new bearings & no wheels on it. I'll post a finished pic with the new wheels, but as of right now this project is basically complete. Very rewarding build for me. I'm not a fan of working on electric motors, so this was a small victory. Thanks for all the help guys.

 

[drivesitfar]

now you have an almost new grinder and an almost new Wilton sitting on your bench. very nice job. so what's next???

has your Dad seen it or a picture of the grinder yet? I bet he'll be smiling for a while after he does and maybe gramps too if they are around since they both used it didn't they?

 

[KF5LCH]

Here's the finished grinder.



What I wouldn't give if the local stores carried balanced stones & wire wheels. The stone is off just a hair, but the wire wheel looks like it was assembled by a drunk. It's going back tomorrow. Even with it out of round, the coast down time has tripled with the new bearings! I can't wait to get some good wheels on it.

Hey there Dean, no, this one belonged to Dad. I have Grandpa's old makeshift grinder pulling buffing duties. It's just an old Dayton 1/3 horse motor with a arbor attachment on it. He had a stone on it, but it's perfect for turning a buffing wheel.

I've yet to show Dad. He's gonna swing by tomorrow to look at it. He'll probably want it back! LOL.