First time!

K

KenH

Well-Known Member
OK, for me it's a first. I'd always figured it was too expensive, to hard to get...... all the usual excuses. Come to find out the grocery store only 5 miles from here carry dry ice! Right there in the frozen food section in a "deep freeze" type thing. Just serve yourself - $1.50/lb. I picked up 3 lb to play with. I happened to have 3 blades ready for heat treating, so I turned oven on.

I also found why you don't use Isopropyl alcohol - it freezes with dry ice! I took container outside, pour a bit of acetone in - nice liquid ice mix.

I had one steak nice type blade that was a bit too long for liquid, so only the blade was fully covered leaving the tang outside liquid. Rc testing shows the tang is 2 points less than blade, just as Sandvik said it would be.

I might have to do this more often/

Ken H>
 
Kind of fun isn't it! I got mine at a grocery store in the same kind of serve yourself freezer thing. I checked the temp of the acetone mix with a thermocouple and it was well below -100 deg. Good thing about using acetone is the next day you can just pour it back into the container after all the CO2 has evaporated.
 
I just had a similar experience with dry ice cryo on a folder blade last week. I was skeptical at first, but it really does make a noticeable difference. I'll be adding that step to every blade I make that will benefit from a cryo treatment. It's definitely worth a couple of bucks.
 
Yep, I was surprised how easy it was to get dry ice, and how cheap it was. I'll be using more of it for sure.

Anthony, good idea on the TC to check temp - I'll try that.... it's Orange Bowl half time, I'll get multi-meter and check it now.

Ken H>
 
OK, just checked and I got a -99ºF in full acetone liquid, but if I help TC probe against block of dry ice it would get to a -103ºF. I think the dry ice needs to be more crushed so the mixture is more of a slurry. I'll try to do better next time. Is that what ya'll do - chip dry ice to form as much of a slurry as possible?

Ken H>
 
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