Tig welding bandsaw blades

[tab]

evening all

just after a bit of advice if anyone can help

my bandsaw blade decided to break on me the other day so i thought i would have a go at welding it back together. cut the old edges off to make a nice flat joint for a butt weld, cleaned the area to be welded front back and sides.
clamped either side of the joint onto the bench with a peice of copper underneath as a heat sink. tacked it at the top and bottom then welded it up. there was no gap so i didnt use any filler, welded up nicely, turned it over full penetration thought brilliant gave it a bit of a wiggle and snap! the blade snapped again, but not in middle of the weld where i would of expected but to the side and out 45 degrees to the top.

welded it back up again and had the same results

its the standard blade that the saw came with so its not the best anyway, should i take this opportunity to buy a better blade or has anyone got any thoughts or suggestions even just to get my by until the new blade arrives?

tom

 

[Shox Dr]

I've welded them before with mixed results. The bigger blades 1" plus seem to hold up better than the 1/2" ones. After welding I would heat it up to dull red and let cool slowly

 

[brightspark]

scarf the joint and silver solder it never fails make up a jig for holding them

 

[pedrobedro]

Slim the ends down on the belt grinder as above and solder or braze. Lots of examples for jigs on the net.

 

[CTB]

Cut the ends to 45 degrees to each other then weld. The bigger area you have to weld, the stronger the joint. A machinist friend told me that trick.

 

[penfold]

I thought bandsaw blades had lapjoints held with spot welds?

 

[printcom]

I've always use silver solder on my bandsaw blades, I was always under the impression that welding them was a no no due to excessive heat.

 

[hotrodder]

Lapjoints aren't very compatible with the blade rollers/guides. This how a 'real' bandsaw welder works... http://www.youtube.com/watch?v=995hjJbsKlk&feature=related, The two halves are clamped and then pushed into each other during the resistance weld. Shower of sparks is the welding, bit that follows is the annealing process. Bigger welds/stronger welds aren't the issue so much as brittleness

This goes into more detail... http://www.metalartspress.com/PDFs%20for%20MSKH/F%20--%20MSK-H%20--%20%20Chapter%206%20--%20Bandsawing%20Extrract.pdf

 

[Rrunnach]

Flash welding is the way to go, most, if not all, decent hori/vert bandsaws will have their own flash weld device intergral to machine. Did numerous re-welds when an apprentice, there was still a knack to it though, more so down to machine.

I had a tour of LS Starrett a while back, very interesting process all round.

BTW, blades are not designed for manual welding processes.

 

[tab]

Cheers for advice, will try what you've all mentioned over the weekend, well apart from the flash welding as i dont have anything to do that with

Just ordered a bi metal blade off ebay for about £12 so just waiting for that to arrive now but i'll have another go at repairing this one so i can use it as a back up should i need it again