Clamping blades for subzero?

[Matt Rochester]

Last time I did heat treat on some thinner stock I got some warpage. They were all straight going in. I'm wondering if I could clamp all 8 together when I place them in the dry ice bath? Anyone doing something similar?

 

[Matt Rochester]

Or taping them together may be easier.

 

[drysideshooter]

What temp were the blades cooled to prior to going into subzero?

 

[Daniel Fairly Knives]

I carefully put my knives in my sub zero slurry just as I was doing a quench... no side to side motion, just slide them straight in. Make sure the slurry is evenly cooling the knife. I do not feel that the sub zero greatly contributes to warp but I'm sure it can.

If you need to straighten do that after they have been in temper for long enough to heat up evenly. Heat then clamp...

 

[Matt Rochester]

The blades were cool enough to handle without gloves. Anyone that has used Cpm154 or similar steels knows that they are very flexible for 5-10 mins out of quench. With the pieces of dry ice in the pan it's tough to get them completely flat on the bottom of my pan. I could place the knives flat on the bottom, put in the ice, and then pour in the denatured alcohol or make a stand to keep them vertical on the spine.

Daniel, are you saying I can basically plate quench them right out of temper to straighten?

 

[Lu1967]

I've had the same problem and now keep the blades clamped during the shallow cryo and temper. Good luck,Lu

 

[Matt Rochester]

This was my solution. Straight going in and straight coming out::thumbup:

 

[elementfe]

Lots of good suggestions.
I started out doing my dry ice quench between blocks of DI and got occasional warpage on thin blades, not too surprisingly.
Now, I simply smoosh my DI and make snow, pour it into an old welding rod canister (only because I couldn't be bothered to grab a piece of pipe off the rack) wrapped in insulation, and slide the blades in a couple at a time.
Much better results.
In theory, I like the idea of using a slurry, but 1) this works, very well, in fact, with as many as twenty blades in a session, 2) it's very thrifty with the dry ice, and 3) I've never achieved a satisfactory system with slurry, though I'm sure that will change when I get a chance to see someone who has a handle on it, go through his process.

 

[drysideshooter]

Especially with CPM154 I always do 20 minutes at 1200, in foil, the day before HT to relieve any stresses that may exist. I plate quench in the foil until the foil can be handled by hand. At that point the blade(s) get put between another set of plates and go directly into the sub zero. Haven't had many warping problems.