MetalworkingFun Forum

my initial thought was to get another beer and i went with it.my next one was to mig and file but i dont think that would get it either.

i would expect it to be hardened and im not sure what heat i can get away with or not on it. i thought i might cut the gear off and press it into a extension tube to make up the length.

why dont i just throw it away? its very old iron made in usa or i just bonded with it quickly, it is new to me today.

May be a case of finding a replacement gear. I'd also want to figure out why it stripped it. Unfortunately it may be more effort that it is worth.

Someone gave me a busted grinder and I used it to make a spray paint can shaker. Made it too good, as it shook the can apart! Paint everywhere and a valuable lesson learned - don't test drive using a full can!!!

Mike, I'm usually all for repairs but in this case it might not be practical. What make is it? what size 4½", 5", 7".
I would imagine that if parts were available it would be the whole armature and probably more expensive than a new grinder.
Once replaced a small bevel gear on the end of the shaft of a Wolf 7" grinder but after machining off the old gear (one piece with the armature) cutting a little keyway and fitting the gear it worked, but I never had confidence in it to really put a lot of pressure on it.

bin it

(05-28-2012, 07:00 AM)krv3000 Wrote: [ -> ]bin it

Oh, Bob - a man of so few words

DaveH

Mike

That is a very common problem with many small tools. Yes those gears are hardened, or at least they are supposed to be. They are also built into the armature shaft, so cannot be replaced without replacing the complete armature, nor can they be welded safely as the heat from welding will transmit down the shaft and damage the windings.

Also what is the condition of the driven gear? It is rare that the pinion gear is worn without the driven gear being damaged.

Most times, if it is just those two parts, it is probably worth replacing them and your repair cost will still be a fraction of what a new replacement would cost. I am supplying these parts to clients regularly.

The most common reason for the damage you show is that the grease has hardened and thrown to the outside of the gear case. The grease has to be soft enough to constantly flow back to the gears to keep them lubricated.

Another reason could be loose bearings. The armature bearings should be replaced at the same time as the armature, and many come from the factory with replacement bearings already pressed on.

Walter

Dave, he got his point across didn't he?

I have 4 of the inexpensive Harbor Freight right angle grinders #91222. They are surprisingly reliable with light use. I usually pay about $15 a piece for them. I have one set up as a grinder, one as a sander, one as a masonry saw, and one with a cutoff blade. The masonry saw unit has seen some fairly heavy use with concrete dust and heavy cuts and is still going strong. I wouldn't bother trying to fix a grinder that had a serious problem.

http://www.harborfreight.com/4-inch-angl...91222.html
[attachment=1741]

I have several of those HF grinders myself. ($9.99 sale coupon)
It saves a lot of wheel changing. I open them all up and pack them with grease though. What is in there from the factory is somewhat lacking, and they will last longer with more / better lubrication.

(05-28-2012, 08:59 PM)Highpower Wrote: [ -> ]I have several of those HF grinders myself. ($9.99 sale coupon)
It saves a lot of wheel changing. I open them all up and pack them with grease though. What is in there from the factory is somewhat lacking, and they will last longer with more / better lubrication.

Good tip. I'll do the same. It may also help to quiet them down a bit. They do tend to have noisy gear boxes.