tempering with a torch?

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wondering if anyone uses a torch for the tempering process...i haven't made a lot of knives, but i had problems with the toaster oven method (temperature inconsistencies, hot spots, etc.) and a couple knives ago, i decided to try tempering with a propane hand torch...the couple knives i've made using this process seem to have come out really well - i'm REALLY happy with the quality of the edge...BUT i haven't pushed them to failure so i don't really know how well they came out...i do know they hold a good edge and chop well without deformity...whether or not they can handle abuse, i don't know...

do you guys think this is a viable method? my concern is that waving a torch around the blade might not give a good, uniform temper all through the blade...it's hard to be sure that the heat has travelled consistently all through the blade...

the way i try to handle this issue is to temper 3 or 4 times, going very slowly, working from the spine inward, slowly getting a consistent color throughout the blade...each temper takes me about 15-20 minutes...

so what do you think? pros, cons? does anyone do this? if so, i'd like to know more about your technique...
 
Since your judging it by color, you'd be better off to heat a bar/block or steel up good and hot and then lay your blade on it till you get the color you want, then quench. Get much more consistent heat that way.
You can either lay it on its spine and get a differential temper, or you could probably lay it flat and get a pretty uniform temper proving its not a really small radius hollow grind.
 
Here's a little trick about getting a more consistant heat in you toaster oven. What I did was to insulate the entire out side of mine using pink owen corning fiberglass insulation. Get the faced insulation and leave the paper out. Then take a piece of aluminium foil and place it over the glass door on the inside, this will help reflect the heat back in. The last thing I did was take an aluminium cookie sheet and cut it to sit on the bottom rack, this will help reflect any direct heat from the bottom element, then place a piece of aluminium foil over the knives when placed in the oven, this will protect from direct heat from the top elements. Place a thermometer on the rack next to your knives, My thermometer never changes temps once I get the oven preheated. And make the bottom cookie sheet into a holding rack, so you can place the blades in, edge up. Hope this helps a little.

Bill
 
Toaster ovens are just that, I believe. Bill offers good ideas and at the top of that list go to a discount store and get a 3 1/2 dollar oven thermometer. It will give you faith in your tempering oven. Don't trust any oven dial settings without checking it with a second reference.

RL
 
i'll second the $3.00 thermometer idea, when i checked my oven it ran 75-100 deg hotter than the dial setting, i bought 2 thermometers just to make sure the front and back of the oven are close....
 
Put a witness piece of steel that is cleaned off and use it to check the thermometer. Color = temp those cheap thermometer are not that accurate sometimes. Gib
 
Like Gib said, colors don't lie. Blue is spring, I like dark straw on the edge.

Anyway, I have had great results with the torch, edge in water. Another way to do this is if you have a set of tongs with big jaws on them, you can heat the jaws with the torch, then grab the tang with them and let the heat move into the blade that way too...

Tim
 
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