Need shaft repair advise

[midlf]

I have a snow blower auger drive shaft that has suffered damage from a bearing failure. I need to figure out how to repair this damage. I'm thinking about carefully adding weld beads around the shaft (adding beads at 180 from each other to prevent distortion), and then using a tool post grinder to get back to the 0.75 shaft dimension.

Any thoughts on this or an alternate method?

[Harold_V]

I don't care how you do the welding, the shaft is going to move on you. It is my opinion that you should do the build-up carefully, then get the shaft in a lathe, and adjust the distorted end(s). Be careful that you don't heat the worm, which may well be hardened.

I'm not sure why you would want to grind instead of turn the repair. It shouldn't be hard, and grinding is a tough job with a tool post grinder. especially if you have a substantial amount of material to remove. Look at it this way. If the weld is hard and can't be machined, the chance the shaft won't break when in use isn't good.

I may not have a total understanding of what you're facing. It would be helpful to see the entire shaft, and to know the length.

Harold

[Willy B]

It looks as though the worm gear is removable. If so, the best approach would be to make a new shaft. It would still be a low buck repair.

Saving such a shaft is possible, but a lot of work and I see no reason to do it in this situation. Now if you want to do it for the learning experience, remove the gear and have at it.

Bill

[737mechanic]

Had a friend of mine last year that had a very simular shaft from a tiller that had almost the same type of damage and even though lots of people said it wouldnt be able to be welded, I welded it up with a mig welder and turned it down then polished it with emery cloth and it looked brand new and is still working fine 1 year later.

[ehughes]

Hello, Have done many repairs like this, mostly on farm machinery, by welding as you suggest. Have always turned in lathe as Harold suggests, maybe finishing up with emery cloth. If the worm won't come off you can probably keep it cool enough by wraping a wet rag around it & allowing time for cooling between welds. Regards, Earl

[steamin10]

This kind of damage is common on home equipment. I would make a new shaft, but a weld repair is faster if you have the equipment. To finish the shaft even a sharp file can get you there, if you make sure to keep the bearing clearance a tight press fit to the shaft, as thats what caused the problem to start with. Go for it. Make it live again.

[Bill Shields]

if it is just a shaft with a removable gear, why don't you just take the worm off and make another shaft from a piece of steel?

Will probably be less work than welding (something that I don't like to do on shafts). The HAZ can cause them to crack in the future.

Again, I recommend based on industrial practice - which would be to not weld on a shaft unless you can heat treat it afterward.

[CarlD]

At work we repaired shafts like that all the time by welding. You turn the worn area down about .025" on a side and past the wear at each end. Then you weld it with soft filler using mig or tig and a helper to roll the shaft as weld. Lay the weld on as if it were a thread and build up in two passes to above the original diameter. After each pass lay the shaft on a solid surface and peen it all around the weld.

You will have to straighten the shaft but before you do take a cut on the shaft so it is about .025-.050" oversize then straighten it. We had an old lathe we straightened shafts in, don't do it in you good lathe. Use a press and V blocks and a dial indicator. When the shaft is straight take it to the lathe and finish it to size.

Give it to the boss and ask for another job, unless your at home doing it. If at home go get a beer and congratulate your self on job well done.

[midlf]

I can see no way to get the worm gear off the shaft. It is shown on the parts diagram as one piece and I can see no joint or pins. If the gear was a separate part there does not appear to be any way to get it off now. It does appear to be hardened. I don't have a picture of the entire shaft but it is about 18" long overall.


I mentioned grinding as I presumed the weld would be too hard to turn. As stated by those with experience it should be turned. Thanks to all for the comments now I can proceed with the repair.

Any ideas on how to keep the welding ground lead connected to the shaft while being rotated to lay a bead down like turning a thread.



I'm trying to repair this 30 year old snowblower because it is built like a tank and all the new snowblowers just look like junk compared to this old warrior. This shaft is no longer available. I would like to repair this and get another 10 or so years out of this beast. Then we both can retire from snow duties when I move to the retirement community. I also want to repair it because I'm stubborn that way, I seldom get rid of anything if I can fix it.

[GlennW]

Grab the gear with soft jaws and part it off just before the damaged area. Turn the stub down to 7/16 or 3/8" and thread it. Make a new shaft and drill and internal thread it and screw the gear on and Loctite it. Just get the rotation correct and thread it accordingly. It'll be straighter than welding and less work.

[jim rozen]

How much is missing off the bearing press fit?

The green locktite bearing retainer compounds (6xx series)
do a darn good job for things missing a few thou.

Just trying to save you some trouble.

Jim

[midlf]

It's a bit much for the locktite product (which I have). It is a 0.75 shaft worn down to 0.66 at the minimum.