Kiln Heating Multiple Blades

brandon0403

brandon0403

Well-Known Member
I just received my Evenheat KF27 and am excited to start finishing the many blades I have profiled and ground. Since I have made several dozen each of the same steel from the same supplier I would like to do as many as possible at the same time. From what I can learn you have some time ( a few seconds from what I've read) to get from the kiln to the quenchant. The first batch of blades that I want to work on are 1095 from Admiral Steel. If I heat up 6 blades at once will my quench on the last blade be effected by the time it sat in the kiln waiting it's turn? On a side note this kiln is larger than I was envisioning, I went with the extra length since the cost difference above the smaller models was negligible compared to the overall cost of the kiln. If anyone is interested I've posted some pictures of the kiln in it's as delivered condition (which was undamaged and unmarred) in another thread.

http://knifedogs.com/showthread.php?34057-Brandon-s-Fantastical-Journey-to-becoming-a-knife-maker
 
IMHO, carbon steels don't lend themselves well to multiple blades in the kiln. You take one out and try to get the kiln door closed, wasting precious time on the way to quench. Don't know how long you'll have each blade in the quench, but even without figuring that in, the remaining blades cooled quite a bit when you first opened the door - and they'll take longer to recover full quenching temp than the kiln interior. I have tried it and my experience has been the quench suffers a bit more on each subsequent blade. I now don't do more than 2 at a time for carbon steels. 1095 in particular is not forgiving.

With stainless, I'll do 6 at a time because that's what I'm comfortable with transferring to the quench plates (12 x 24 plates usually fit 6 pretty easily)
 
I would suggest no more than three in a batch. I have an Evenheat 22.5. My blades are set edge up in grooves cut in a fire brick, putting them close and centered until the thermocouple. With your larger oven, you might consider adding a brick or two to lessen air space. The fire bricks will hold heat and shorten recovery time from opening the door. By the time I wipe the blade off, check warp and correct if necessary, and wait 2 or 3 minutes, the next blade is ready to come out.
 
Knifemaker.ca said:
IMHO, carbon steels don't lend themselves well to multiple blades in the kiln. You take one out and try to get the kiln door closed, wasting precious time on the way to quench. Don't know how long you'll have each blade in the quench, but even without figuring that in, the remaining blades cooled quite a bit when you first opened the door - and they'll take longer to recover full quenching temp than the kiln interior. I have tried it and my experience has been the quench suffers a bit more on each subsequent blade. I now don't do more than 2 at a time for carbon steels. 1095 in particular is not forgiving.

With stainless, I'll do 6 at a time because that's what I'm comfortable with transferring to the quench plates (12 x 24 plates usually fit 6 pretty easily)
Click to expand...

Thanks for the quick reply. After posting that I attempted to do 6 at once just as an experiment almost assuming that I would need to give all 6 another try to get a good result. After doing all 6 and a small test piece (small rectangle of the same steel) your conclusion about only doing 2 at once makes a lot of sense. My quench can is directly below and a little forward of my oven door so from oven to quench is probably less than a second. I see a drop in temperature once the oven equalizes again of about 10-15 deg. and comes back up to full temp in under a minute and giving the steel a few minutes to come fully back up I've already hung up my quenched blade waiting for temper.
 
LRB said:
I would suggest no more than three in a batch. I have an Evenheat 22.5. My blades are set edge up in grooves cut in a fire brick, putting them close and centered until the thermocouple. With your larger oven, you might consider adding a brick or two to lessen air space. The fire bricks will hold heat and shorten recovery time from opening the door. By the time I wipe the blade off, check warp and correct if necessary, and wait 2 or 3 minutes, the next blade is ready to come out.
Click to expand...

After doing 6 at once I think I will stick with 2 at a time for now, after quenching the second blade I can stick 2 more in the kiln and hit the add time button on the RM3 controller. I like your idea of adding some fire brick in the back, while I'm sure the 27" length will come in handy in the future, I really don't even need the back half of the oven right now. I may get ahold of Evenheat to see what they recommend is the best orientation and size of bricks to add to maximize my oven for the smaller blades I am doing for now.
 
I have the 22.5 I do 3 max at a time. I also started using pizza stone that I cut for a shelf 1/2 thick works nice, also was thinking of filling the dead space further back with some fire bricks.
 
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