I have a customer looking for a Kosher slaughtering knife, so its a 18x3" blade in M390, plus the handle length, so around 23.5" long total. Does Jarod Todd do blades this long or does anyone have any recommendations for someone who can? It's only one blade. Thanks!
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Big blade heat treater?
- Thread starter Taz
- Start date
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Pretty much any commercial HTer can do a 24" blade. Jerrod would be my recommendation.
I know this sounds funny to many folks, but be sure to use kosher polish on the chalef blade .. there is such a thing.
Many shochet will only use a chalef from a approved maker.
Here is one of my older posts on the subject:
For those who aren't familiar with this subject, the shochet ( kosher butcher) uses a shechita ( also shehitah - ritual kosher slaughter) knife called a chalif/chalef (halif) to perform kosher slaughter. This is done under the supervision and inspection of a rabbi. The cut must be quick and clean as well as painless as possible. The rules of the slaughter are very strict and any variance or error renders the animal un-usable.
The standard challif today are made by grinding the blade ( stock removal), but some are forged. There are specific rules about smoothness, edge condition, and length. the main rule is that the edge must be flawless...even a microscopic nick will make the slaughtered animal traifa ( un-kosher).
There are several Jewish smiths who specialize in making challif, but any knife that is sharpened and polished to the degree that will pass inspection is allowed. Several makers here in Shop talk make these knives.
Sharpening challif is similar to sharpening Japanese knives. The edge is refined and polished in a continuous succession of grits, ending with a perfect edge. Taking the surface to a grit of 100,000 is not unknown, but most are around 16,000 to 25,000 grit finish.
Shalom -Stacy
Other past discussions:
https://www.bladeforums.com/threads/kosher-knife.733094/
https://www.bladeforums.com/threads/an-interesting-view-of-sharpening-sharpness-for-god.1526372/
https://www.bladeforums.com/threads/shechita-judaism-miller.83208/
https://www.bladeforums.com/threads/kosher-knife.733094/page-2
I know this sounds funny to many folks, but be sure to use kosher polish on the chalef blade .. there is such a thing.
Many shochet will only use a chalef from a approved maker.
Here is one of my older posts on the subject:
For those who aren't familiar with this subject, the shochet ( kosher butcher) uses a shechita ( also shehitah - ritual kosher slaughter) knife called a chalif/chalef (halif) to perform kosher slaughter. This is done under the supervision and inspection of a rabbi. The cut must be quick and clean as well as painless as possible. The rules of the slaughter are very strict and any variance or error renders the animal un-usable.
The standard challif today are made by grinding the blade ( stock removal), but some are forged. There are specific rules about smoothness, edge condition, and length. the main rule is that the edge must be flawless...even a microscopic nick will make the slaughtered animal traifa ( un-kosher).
There are several Jewish smiths who specialize in making challif, but any knife that is sharpened and polished to the degree that will pass inspection is allowed. Several makers here in Shop talk make these knives.
Sharpening challif is similar to sharpening Japanese knives. The edge is refined and polished in a continuous succession of grits, ending with a perfect edge. Taking the surface to a grit of 100,000 is not unknown, but most are around 16,000 to 25,000 grit finish.
Shalom -Stacy
Other past discussions:
https://www.bladeforums.com/threads/kosher-knife.733094/
https://www.bladeforums.com/threads/an-interesting-view-of-sharpening-sharpness-for-god.1526372/
https://www.bladeforums.com/threads/shechita-judaism-miller.83208/
https://www.bladeforums.com/threads/kosher-knife.733094/page-2
Yeah, I did some several years ago and the customer who ordered them did the polish with diamond emulsions on a buffer to get their final finish that they needed. I gotta send pics of the highest finish I can do with my equipment to make sure it is OK, but they may be able to do the final polish themselves on the blade surface. Customer said as long as it wasn't a forged/black/rough finish it would be OK on the blade itself. I have the Sun belts up to 5 micron, so I will send pics of what that finish looks like. I found CPM 20CV in the sizes I need, so the HT question and the finish question are the 2 hurdles to overcome! I do have 1 micron, 1/2 and 1/4 emulsions CBN and diamond for the edge itself.
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
Moderator
Knifemaker / Craftsman / Service Provider
- Joined
- Aug 20, 2004
- Messages
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It is best to hand polish on charged leather strops (separate strop for each paste) for diamond paste over 2,000 mesh/8 micron. Use a drop or two of silicone oil as a carrier. Slow even strokes will take the edge to extreme polish and sharpness. You also have to be wary of forming a full wire edge that seems to flex with any pressure. Remove the wire after buffing as usual and then finish each paste grit done by hand with a few passes at a higher angle to remove any new wire.
While a polished edge at 100,000 mesh/ .25 micron is fun to do, it is not really any sharper than one done at 50,000mesh/.5 micron. All you get is smoothness of the surface above the edge. A very fine grain steel has grains at 10 microns (size 10 grain, which is nearly impossible to attain in a knife blade). You can't really make the edge any thinner than that or grains start falling out creating a microscopic serrated edge. Examination with a 10 or 20 power loupe, as is normally used, will show the edge as a perfect line. It will take a metallurgical microscope to see the serrations at such a fine polish.
If you want to have some reading fun, read up on preparing metallographic specimens. They take polishing to the ridiculous, as fine as .1 micron.
While a polished edge at 100,000 mesh/ .25 micron is fun to do, it is not really any sharper than one done at 50,000mesh/.5 micron. All you get is smoothness of the surface above the edge. A very fine grain steel has grains at 10 microns (size 10 grain, which is nearly impossible to attain in a knife blade). You can't really make the edge any thinner than that or grains start falling out creating a microscopic serrated edge. Examination with a 10 or 20 power loupe, as is normally used, will show the edge as a perfect line. It will take a metallurgical microscope to see the serrations at such a fine polish.
If you want to have some reading fun, read up on preparing metallographic specimens. They take polishing to the ridiculous, as fine as .1 micron.
I usually use balsa or leather for my emulsions. Ken Schwartz (RIP) had formulated some diamond compounds to be used on buffing wheels and stuff a while back. I will kinda treat it like sharpening/stropping a straight razor!