Bandsaw blade welding

[Vinny]

I'll use the welder next time, this time I'd have to take it back out of the saw and those cheap chinese screws will only go in and out a few more times!

[Highpower]

Isn't that the truth!

I just had to drill and helicoil the lower blade guide bracket on my 7x12 saw. I went to install the table for vertical cutting and the mounting screws just kept turning, and turning, and turning......

[Dr Stan]

Are you familiar with the technique to grind the ends with complementary angles so you don't have to have both ends absolutely square?

Flip one end of the blade so you have the teeth of one end lined up with the back of the blade on the opposite end. Grind the two ends together and then match up the ends for welding. Perfect fit up.

[Vinny]

Never heard that one. I just put them together and grind. It only takes 10 or 20 tries to get them square. I'll try that on the next one. Thanks!!

[Vinny]

I tried tempering. Never saw blue, I stopped at the first color I saw which was a very very dim orange. It stayed silverish until I saw that orange. Didn't think to grab the optical thermometer until after it cooled down to about 205F.

[TomG]

You have to look at the clean area where you ground, and as I said it happens fast, so if you are using a torch, it needs to be a small flame. We aren't talking glowing steel here, just subtle colors that show up almost as soon as you apply the heat.

Tom

[Vinny]

Ok, that makes sense. Looks like I'll be making a new blade soon anyway, Apparently it wasn't as square as I thought when I welded it 'cuze there's a bounce in the bandsaw when it gets to the weld. I'll squeeze every bit of life out of this blade that I can. I'm making a dresser for the surface grinder and had to cut the base and the handheld dresser I already had - and I was just at wholesale tool yesterday and completely forgot to pick up the other dresser for my other grinder. Ooo... That means another trip to Wholesale Tool!!! Anyway, got the two pieces cut that I needed to for now. In the mean time I think I'll grab some old blade and experiment with the torch.

[RobWilson]

(12-14-2015, 06:10 PM)TomG Wrote:

• Weld it
  
• Anneal it bright red (not orange)
  
• Grind it
  
• Temper it to blue ?? 
  
• If that doesn't work, build my soldering fixture and silver solder it
  

          Tom

The very fact that the blade has been Annealed

Quote:Annealing is a heat process whereby a metal is heated to a specific temperature /colour and then allowed to cool slowly. This softens the metal which means it can be cut and shaped more easily. Mild steel, is heated to a red heat and allowed to cool slowly.

Means there is no need  to Temper . Tempering is used to reduce the hardness of hardened steel , so if the blade has been annealed  it can't be in a hardened state . 



Rob 

[Dr Stan]

I'll have to respectfully disagree as grinding the weld flush re-hardens the weld thus requiring a second round of annealing.

Here's a good YouTube on how to resistance weld a bandsaw blade including a 2nd tempering/annealing step. 

https://www.youtube.com/watch?v=GBwr3oPJHcs

[RobWilson]

(12-19-2015, 09:44 AM)Dr Stan Wrote: I'll have to respectfully disagree as grinding the weld flush re-hardens the weld thus requiring a second round of annealing.

Here's a good YouTube on how to resistance weld a bandsaw blade including a 2nd tempering/annealing step. 

https://www.youtube.com/watch?v=GBwr3oPJHcs

With respect could you please explain how grinding the blade heats the blade up to a sufficient temperature that it becomes hardened ?

Rob