Quenching bent screwdrivers for optimal hardness

[Blue98GT]

I need to make some "custom" pry bars out of small screwdrivers to remove an airbag without removing tons of trim.

What's the proper (or approximate) quenching liquid to retain optimal hardness? Motor oil? Water?

These are harbor freight Pittsburg red handle screwdrivers with the black tip. I'm heating with propane and bending in a vise. Thanks.

 

[MoonRise]

Proper heating and quenching (and then TEMPERING) for a steel object depends on

the EXACT alloy of steel you are dealing with.

Quench some O1 steel in water and it will likely crack during quenching (quench rate too high for the alloy).

Heat up some A2 steel and it can quench in air. Quench it in oil or water and it will crack (quench rate too high).

Try to quench some W1 in oil and it might not get hard enough (quench rate too low).

And I have no idea what alloy some HF screwdrivers are made of.

 

[seber]

Best guess would be oil hardening. Heat to cherry red and quench then quickly heat to straw and quench. Any oil will do since you don't know the exact alloy anyway. Used motor oil is as good as any and may give some corrosion resistance from the free carbon.

 

[Blue98GT]

Will heating to less than an orange color ruin any kind of heat treatment on the tips? I just need it hot enough to bend easily.

 

[MoonRise]

Will heating to less than an orange color ruin any kind of heat treatment on the tips? I just need it hot enough to bend easily.

Yes. If you heat up the steel, you will change the quench/temper characteristics.

Depending on the steel alloy and the specific existing heat treatment and properties, you could make the steel harder (and more brittle) or softer.

And you can also melt the plastic handle as you heat the steel.

 

[seber]

If you are not going to full temper temperature (somewhere between 400f and 700f) then just quench it from your hottest point.

 

[Blue98GT]

Figure I'd post what I'm doing.

https://www.dropbox.com/s/knneemrmvji11wm/tool2 (edited-Pixlr).jpg?dl=0

https://www.dropbox.com/s/lpwvdrq7jo46f7g/tool1 (edited-Pixlr).jpg?dl=0

https://www.dropbox.com/s/goz14mcv9gkxtr7/tool3 (edited-Pixlr).jpg?dl=0

 

[rlitman]

Figure I'd post what I'm doing.

https://www.dropbox.com/s/knneemrmvji11wm/tool2 (edited-Pixlr).jpg?dl=0

https://www.dropbox.com/s/lpwvdrq7jo46f7g/tool1 (edited-Pixlr).jpg?dl=0

https://www.dropbox.com/s/goz14mcv9gkxtr7/tool3 (edited-Pixlr).jpg?dl=0

Nice. Those will make good brake spoons when you're done with this.

 

[Blue98GT]

Well I get to test these out tomorrow at the salvage yard.

 

[Blue98GT]

Well, they worked pretty well. None of the tips broke which is a plus. The tips did not deform at all. Pretty impressed with these Harbor Freight screwdrivers. Not sure if the black tips are just painted or are actually hardened. I'd venture to say they may be hardened since no tips bent. I was prying pretty hard with them enough to scuff the metal.

 

[Iowafox]

Well, they worked pretty well. None of the tips broke which is a plus. The tips did not deform at all. Pretty impressed with these Harbor Freight screwdrivers. Not sure if the black tips are just painted or are actually hardened. I'd venture to say they may be hardened since no tips bent. I was prying pretty hard with them enough to scuff the metal.

I have heard that for the money those screwdrivers you used are some of the best and hold up really damn well. I know a few people who use them over snapon and other brand names since they bought them when they where first getting into there jobs and where planning to upgrade once they broke them. One of the guys broke the first one after 10 years of so of regular use and said for the price of the whole new set he couldnt even get 1 brand name driver. So he simply replaced the whole set and has had no regrets. Almost makes a guy want to go and get a set for home.

Also I have used old drivers to make into picks and bent prybars as well before. I usually use old motor oil or rain water what ever is closer for cooling it once it's how I want.
I have made a few mini picks from old pocket screwdrivers with messed up heads and I found the best way is use a sander to get the shape, motor oil to cool it, wipe it off, heat it up then bend it how you want and then motor oil for best results. It might not be the best way but for shade tree tinkerers it works good.

 

[Blue98GT]

I've been quenching in my used motor oil container. Smokes pretty good. So far none of the heated tools have come out soft with this method. Couldn't give a rockwell hardness. They just need to be hard enough to not deform during use and not too hard that they crack and chip.