Anybody welded on a core bit shank?

[Hersheyfarm]

I have an old spline drive core bit. Milwaukee. My current rotary hammer is sds max. Thinking about buying a cheap sds bit from harbor freight and welding it on. I have no ideal what metal it is. Hard stuff. The shank is not replaceable on this one. Any advise?

 

[5030]

Runout as well as destroying the heat treat will be an issue

 

[Root Cause]

Most bits in a machine shop are made of M2 commonly known as high-speed steel or HSS.
My experience is mostly TIG welding. Stainless sticks to almost anything.

My guess is that you won't be happy with the result as keeping both pieces aligned will be difficult.
I might spend my time looking for another solution but if you know someone with a lathe, you can chuck both pieces in the headstock and tailstock while you weld. Hopefully someone has a better idea but that's all I got. Good luck.

 

[5030]

you can chuck both pieces in the headstock and tailstock while you weld.

That can be detrimental to the lathe as the current flowing can cause grief with bearings and other stuff.

 

[mrmikey]

I've cut the shank off a smaller SDS bit and welded it to a larger oddball brand bitt. Used tig and ss rod, it held for the two holes we had to do. Only reason I did it was it was a 1/2 hour drive to town to buy a $$$$ bitt for two holes.

 

[2manyrocks]

odds of ruining what you have seen pretty high. Is there some kind of conversion adapter available?

 

[ROUSTABOUT]

That can be detrimental to the lathe as the current flowing can cause grief with bearings and other stuff.

Not if grounded right.

 

[5030]

Unless you have a rotatable ground clamp, I'd refrain from doing it. Not my deal so I don't much care actually. Never happen on any lathe I own.

 

[Hersheyfarm]

odds of ruining what you have seen pretty high. Is there some kind of conversion adapter available?

Actually there is. just ordered a Milwaukee one. Cheapest I found..$130. Have other bits to use it on. So we will put welding it on hold. I’ve already wrote off all these spline bits, so if this adapter holds up it could be a win. If not, we weld. I ain’t scared.

 

[Root Cause]

That can be detrimental to the lathe as the current flowing can cause grief with bearings and other stuff.

Maybe on some small lathe but they endure heat. As for grief, I guess you are saying side pressure but that is exactly what a lathe tool does- apply side pressure. If someone has a $200 mini lathe you may well have a point. My experience is with Leblond and Clausing lathes up to 25 hp and doubt 2 more generations can kill them. After going down this useless rabbit hole, the result is that doing this at all may not yield what the op needs.