Efficient annealing clean up

A

Aktundra

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Feb 17, 2019
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I have been making blades out of old saw blades. This has required annealing the tang to drill holes for the pins. At first I heated the tang with a propane torch till red hot and no longer magnetic. But results were inconsistent. (Assumed I needed to hold the heat longer) Next I heated to red hot and non magnetic, then jammed them into the dying charcoal brickettes after a BBQ, and left till morning. This seems to work 100%, however leaves substantial blue discoloration on the steel.
How is the best way to grind/ polish out the discoloration ? I’ve run through several grits of sandpaper, & tried metal polish. Just seems like it takes a lot of time.
Is there a better way to anneal without causing the discoloration?

if discoloration is inevitable, is there an efficient way to buff the metal back to bright ?
 
OLD ( pre-1950) sawblades over 36" diameter are probably some sort of carbon steel. Most saw blades since then and below that size are likely high alloy or HSS steel. It will actually harden by heating to red and slow cooling, because they are air hardening steels. Annealing these steels takes a HT oven and many hours of very slow cooling at 25-50 ° per hour.

Best solution - Use a carbide drill bit.
 
Aktundra said:
I have been making blades out of old saw blades. This has required annealing the tang to drill holes for the pins. At first I heated the tang with a propane torch till red hot and no longer magnetic. But results were inconsistent. (Assumed I needed to hold the heat longer) Next I heated to red hot and non magnetic, then jammed them into the dying charcoal brickettes after a BBQ, and left till morning. This seems to work 100%, however leaves substantial blue discoloration on the steel.
How is the best way to grind/ polish out the discoloration ? I’ve run through several grits of sandpaper, & tried metal polish. Just seems like it takes a lot of time.
Is there a better way to anneal without causing the discoloration?

if discoloration is inevitable, is there an efficient way to buff the metal back to bright ?
Click to expand...
Do you have pictures of saw you use ? Most of them/circular one for wood/ are around 50 HRC so you need to HT them to get proper hardness for knife. Ordinary HSS drill bits will drill hole easy in saw.......Except if that was HSS saw for metal .
 
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