12-19-2015, 07:28 PM
I have no idea how Starrett and Enco grind their blades. Perhaps they use coolant.
All I can say is that in my experience, tempering the blade after grinding results in a MUCH less brittle blade, and I am not alone in that assertion. DoAll recommends that a blade be annealed before and after welding. Here is a quote from one of their blade welder manuals:
"Imperial Bi-metal and narrow carbon saw bands require special treatment to protect a weld against accidental breakage. It is recommended that welds in these saw bands be annealed BEFORE removing for grinding and AFTER grinding as well."
(Their caps not mine)
And here is a commercial blade company (BandsawBladesDirect) that does a secondary anneal as well:
https://youtu.be/muqWF4UWUpc
The Lazy Machinist video (which I have never seen) is exactly the way I have welded blades all my life and will result in weld that is every bit as strong and flexible as the band itself.
In my opinion, I doubt that the grinding process is hardening the blade from heat. It is more likely a work hardening process from the action of the wheel on the thin cross section of the weld. Whatever the mechanism though, grinding definitely makes the weld harder than the surrounding blade.
Tom
All I can say is that in my experience, tempering the blade after grinding results in a MUCH less brittle blade, and I am not alone in that assertion. DoAll recommends that a blade be annealed before and after welding. Here is a quote from one of their blade welder manuals:
"Imperial Bi-metal and narrow carbon saw bands require special treatment to protect a weld against accidental breakage. It is recommended that welds in these saw bands be annealed BEFORE removing for grinding and AFTER grinding as well."
(Their caps not mine)
And here is a commercial blade company (BandsawBladesDirect) that does a secondary anneal as well:
https://youtu.be/muqWF4UWUpc
The Lazy Machinist video (which I have never seen) is exactly the way I have welded blades all my life and will result in weld that is every bit as strong and flexible as the band itself.
In my opinion, I doubt that the grinding process is hardening the blade from heat. It is more likely a work hardening process from the action of the wheel on the thin cross section of the weld. Whatever the mechanism though, grinding definitely makes the weld harder than the surrounding blade.
Tom