welding a bimetal hole saw

[The Cobbler]

I have a large bi metal hole saw where I inadvertently stripped out the threads where the mandrel goes in ( didn't have the pins set in place)
would an easy repair would be to weld a cap on from another hole saw? is there anything I need to know since it's hardened?
thanks

 

[Com_VC]

If you have a spare or old arbour you could also tack weld that into place and just leave it there permanently.

 

[matt_i]

There are the issues with concentricity...its good to use a lathe to do your best work there.

However, I think you could do a decent job if you had tightly fitted pins that aligned the two drive-holes, and weld on another center-section to the existing one.

 

[AA/FC]

I have done exactly what you're talking about, for the same reason that you're talking about.... I didn't have any problems. It's just a hole saw. You can't ruin it any worse than it already is. Go for it!

 

[bad_idea]

If you have a spare or old arbour you could also tack weld that into place and just leave it there permanently.

Done that countless times at work. Running a hole saw through a bulkhead or deck, it catches, and strips the threads on the hole saw. Have the welder throw couple tacks on it and keep going. Hole saws and arbors are a consumable item for us. I imagine you could cut the tacks and keep the arbor if you can get the hole saw off of it.

 

[The Cobbler]

not all that concerned with concentricity . they run at slow speeds, and I can alingn it well enough with a bolt thru the pcs.
I could use an arbor but then it takes up more height (not a big deal) but I do have several toast hole saws that I could get the cap from. also this is a 4" hole saw, barely used and i'm cheap!

 

[rsanter]

I would kill the remainder of the threads, weld a nut on it

 

[The Cobbler]

a nut on the top of the saw would negate the use of the pins, the top plate is too thick to be much value from a nut welded underneath .

 

[racingtadpole]

It’s Bi Metal, so only the teeth are hardened (marketed as a feature but reality is it’s a manufacturing cost efficiency).
Me, I’d weld the thread up chuck it in the lathe to bore it for new threads. If I didn’t have a lathe I’d probably look to a drill press. Use the arbor to centre it, then clamp it and drill for tap size

 

[racingtadpole]

a nut on the top of the saw would negate the use of the pins, the top plate is too thick to be much value from a nut welded underneath .

Or you could weld the nut on the inside, reduces the cutting depth but how often do you cut full depth with a 4” holesaw?

 

[The Cobbler]

, tthe top plate is too thick to be much value from a nut welded underneath .

Or you could weld the nut on the inside, reduces the cutting depth but how often do you cut full depth with a 4” holesaw?

top plate is too thich for a nut to be any value

 

[racingtadpole]

Sorry no idea how I missed that

 

[The Cobbler]

Sorry no idea how I missed that

hey, it happens LOL.