Can you weld a motor?

[teamtom]

The shaft actually...I wanted to weld a sprocket to the shaft of a DC motor, can this be accomplished without messing up the internals of the motor? It seems like a dumb question but the result could have me wishing I had asked the dumb questions.
Tom

[rich bures]

motor

make sure you ground to the shaft your welding on - not the motor case -

[teamtom]

I probably have to clamp the ground around the sprocket but otherwise it's o.k.?

[dynasim]

I think most would say to provide a temperature barrier(like a wet rag) between the weld location and the motor, but I have never done anything like this. I have welded(brazed) pump connections like that, though.

Chris

[Craig in Denver]

Could you use a sprocket with a hub and set screws? Maybe McMaster-Carr would have something? Or you could make your own. Maybe a local machine shop would make the hub and you could weld it to the sprocket.

If you decide to weld it on, I second the idea of a wet rag wrapped tightly around the inside to dissipate the heat.

[teamtom]

It is a very little shaft (that's what she said...) and I wanted more grip than a set screw, maybe I'll use a thru-roll pin instead. Thanks for the input!
Tom

[teamtom]

Here's a pic, the shaft is 8mm and I was afraid the roll pin might not be strong enough.

[Dave F.]

I would be more concern about warping the shaft from the heat. of the weld just my .02 cents Dave F.

[aametalmaster]

I would go with a bushing and a set screw but thats just my thought...Bob

[teamtom]

Good points, I am officially not going to weld the sprocket. Thanks for all of the helpful replies!
Tom

[aametalmaster]

If you need a bushing made give a yell...Bob

[Craig in Denver]

It is a very little shaft (that's what she said...) and I wanted more grip than a set screw, maybe I'll use a thru-roll pin instead. Thanks for the input!
Tom

There is no reason to use a single set screw. Use 3 or 4 if you'd like. You have 360* to work with. Also, the shaft looks long enough to get a wet rag between the weld and the 'delicate' parts, so that would still work.

aametalmaster: If you need a bushing made give a yell...Bob

Now there's an offer I'd be jumping on.

[Thomas Harris]

If you use setscrews, you may consider giving the shaft a flat or dimple where the set grips the shaft to prevent slipping. The motor shaft is small, so a dimple would likely work best. And two setscrews is a heap better than one.

[metalmeltr]

[QUOTE=teamtom;341124]It is a very little shaft (that's what she said...)

No thats what she said to you.

[engnerdan]

There should be no reason that roll pin should not hold. As long as the mating slot in what ever part is a close fit (no slop). Those motors were used for Ford factory radiator fans (I have several in my garage) and they are very powerful, the factory design is to use the roll pin and it works just fine in the fan. Depending on the size of the hole in the sprocket I would most likely machine a hub that engages that roll pin and then has a set screw to hold it onto the shaft. Once you have the hub made lightly tighten down the setscrew onto the shaft just enough to leave a very faint mark. Then machine or file a flat onto the shaft for the set screw. If you don't do this the set screw will upset the metal to enough that you will not be able to remove the hub in the future.


This is for a fighting robot or something of that sort right?


-Dan