Thread: Razors and Belt Sanders

I recently received a razor that had been sharpened on a belt sander. The scratch marks from the belt extended about 3/8" up from the edge into the hollow. I sharpened it but have to recommend to folks buying razors that they avoid any razor that has been taken to a belt sander. The reason is that the heat treat will be taken out of the edge in about 1 second on a belt sander. I know this as I looked at the edge under magnification and saw little blue curls of steels along the edge. What a shame!

Howard

I know very little about honing/sharpening straights, but good God, the idea of using a belt sander would never even occur to me!

I cringed as soon as I read the title. I had a cheap pocket knife I used to use at work for cutting open boxes and such, and I used to give it quick touch ups on the bench grinder. It looked like garbage, but it served it's purpose and I wasn't going to waste time sharpening a ~10 knife. But on a straight? *shakes head* Most people must view straight razors as similar to any other knife, when in reality they are a totally different beast.

It's been hard with the number of experts rolling in here destroying bevels and blades, lately. These can be such delicate edges.

I make and sharpen knives using a 2x72 belt grinder (gives an awesome edge) but can't for the life of me imagine sharpening a straight using it. Way too aggressive and way too much heat for that thin of a blade.

Charlie

I attended a lecture by a metallurgist who works for Rolls Royce and he told us of their new equipment for measuring heat at the edge of steel. Heat treat temps are exceeded in less than a second at a thin edge like a knife or razor and it's not only the grinders. He said the worst offender was a buffing wheel (linen or cotton or paper) because no one thinks about them as heat generators. He only uses hand held hones now and he makes knives of unbelievable beauty and thinness and they hold their edge.

I like slurry honing because the slurry prevents any possibility of heat treat being lost. There was a posting on a knife forum about a guy who was using a spyderco v-stick so fast that a curl of hot metal flew off and landed in his eye. Not good and most unexpected using that tool! He must have been going really fast.

Sooooo... for razor honing and knife honing I use my Shaptons wet and my coticules with slurry. We work too hard, as bladesmiths, getting an edge to where we want it to ruin it with a belt grinder taking out the heat treat.

Anyone putting any type of cutting blade on a belt sander or power wheel needs a swift kick in the B___. The heat genorated will kill any temper the blade may have.

Wow. I wonder if the seller cuts his sandwiches on a table saw.

Originally Posted by cyberbiker

Anyone putting any type of cutting blade on a belt sander or power wheel needs a swift kick in the B___. The heat genorated will kill any temper the blade may have.

Well, kick me in the B_____. I've don it with dozen of blades and I personally know of several full time makers who do it as well. The trick is keeping the blade cool. Don't wear gloves and if it gets uncomfortable to the touch, then dunk it in water. You'll be fine. You do realize that it takes around 400 degrees for most carbon steels to adjust the temper?

Charlie

Originally Posted by CharlieTN

Well, kick me in the B_____. I've don it with dozen of blades and I personally know of several full time makers who do it as well. The trick is keeping the blade cool. Don't wear gloves and if it gets uncomfortable to the touch, then dunk it in water. You'll be fine. You do realize that it takes around 400 degrees for most carbon steels to adjust the temper?

Charlie

Changes start at 350. The biggest problem is that most people try to grind off all at one time. I've used grinders myself.