How to anneal bandsaw blades and other hard metal?

[george wilson]

To anneal the end of your bandsaw blade: Just polish the end of the blade so you can see the bright metal. Heat it up with a Mapp gas torch slowly,watching the colors change.It will turn yellow,brown,purple,then blue. The next color will be a dull gray. That is when the blade is annealed. I pre heat the top of the sand in a can full of sand till it's good and hot. Then,heat up your blade as described. When the blade turns gray,stick it into the hot sand so it cools slowly.

You can just drill the blade without annealing by running a carbide tipped masonry bit AT HIGH SPEED,and drilling right through the blade. The high speed of the tip will heat the metal
up,and scoop it right out. You can drill holes right through files like that. I've drilled right through SOLID,ALL HSS old power hack saw blades like that. Be careful to not let your masonry bit get TOO hot,as the brazing will melt,and the carbide tip will fall off.

DO SECURELY CLAMP the bandsaw blade's end before attempting to drill it. If the blade got caught,you would get a severe mauling from the blade.

Your lathe bed was induction hardened,or flame hardened to a depth of probably 1/16",or a little more. On a newer lathe,you can see the hardening colors left on the end of the ways.

 

[Nelson]

Excellent instructions- I am going to give it a go!

Thank you!


Nelson

 

[Tony Wells]

It's hard to control the tempering of some things. I have tempered knife blades using indirect heat. This would work on hacksaw blades. I've used the large power hacksaw blades for knife material, and to draw them back, or temper them, I take a piece of steel about 1/2" thick and large enough to lay the blade on. Heat it to a red heat, and place the back edge of the knife in contact with the hot plate. The heat will migrate from the back to the sharp edge fairly quickly. If you watch, the straw color (or whatever you are looking for, depending on the material) will appear in a few seconds. Then you quench in oil. The effect is that the sharp edge will retain it's hardness, but the back will be a bit softer, and give the blade a little flex.