Sharpening on a Belt Grinder?

S

Scott Free

Joined
Sep 15, 1999
Messages
3,319
I've only made about a half dozen knives or so. To put the edge on them I've used a big diamond stone and then a Sharpmaker. I know others put the edge on the blade with the grinder. How do you do this? I know I've seen references to using a slack belt, but that's all I know. Any help?

Scott
 
I sharpen edge down (belt runs downward) on the platen. Start with a 220 grit belt, then go to 400. Grinder running on slowest speed to keep the heat down and keep me from gouging and making a wavy edge.
After I have the bevel set with the 220 grit belt, I switch over to the 400 and try to raise a burr along the edge. For the last couple passes I usually move just above the platen and use the slack belt portion. The belt is still very stiff right here, I'm literally running just off the top of the platen. The idea isn't to convex the edge, its to not have the platen edge behind the belt. This removes any gouging you get from the platen edge and blends the bevel out nicely.
If I do all that right I can go right to a ceramic stone and put a wicked edge on with just a few seconds more work. With about a minutes time I can have the edge bevel mirror polished and hit the strop a few times for good measure. It gives a very good edge without too much effort.

I wouldn't say that this produces any better results than I used to get just sharpening on stones, but it is faster when your trying to set the bevels and I've found that I don't screw up the finish as often. Used to be I'd get impatient and start leaning on a coarse stone....then slip and gouge the middle of the blade really bad :mad: :grumpy: . Haven't done that since I started using the grinder :cool:
 
Some folks use the platent as backing. It helps keep the edge crisp and true. I never could get the knack of that method so I stayed with slack belt. I was thinking about making a grinding attachment /platent that lays on top so you'd still be using the same actions as slack belt but you'd have the benefit of the platent backing the belt. Might work out, might not.
 
I used to use my disc sander going edge up until I had a knife ripped outta my hand and thrown into the concrete in my garage... I was not impressed. Better than my belly though. Since then I tried the edge down method but found I was left with a very fine burr that would quickly dull after limited use. lately I've been using a lansky to put my bevels on and then stropping to get the nice fine edge we all love. To save time I am going to do the edge down technique and then finish it off with the lansky and strop. FYI: A guy can always bend the lansky a bit if he does'nt like the preset angles. The clamp bends quite easily. So far the lansky combined with a strop (which keeps the angle exactly the same as opposed to free hand on a belt) has been the best method I have experimented with. Be prepared to spend some time though if you don't pregrind an edge bevel on your knife first. Even with the "extra course" diamond stone it takes quite a while to put an edge on. Hope this helps. :D

Mike Coughlin
 
I use a 120 grit belt, and then move to 400 grit.
The lower grits produce less heat than the higher grits.
After 400 grit, I use a mouse pad and some 600 grit wet/dry sandpaper, and then a leather strop.
This is NOT a convex edge, but works very well for me.:p
 
I put the initial edge on stainless user knives on the flat platten, edge up, with a structured belt, being careful not to heat the tip. I used to finish it on a buffer, edge down. Recently Tai Goo shared one of his stropes with me and I use it in place of the buffer. It's faster, more accurate and makes it alot sharper. It's a piece of wood with cork and paper over it. He loaded it with a fine abrasive. Check out his website. I have to credit him with changing the way I sharpen knives now. Collectors pieces are all by hand, finished with the strope.
 
Keep using your diamond stone and sharpmaker.

Your customers (or friends/family if you're not selling yet) will likely have some sort of stone. They will NOT have a belt grinder to re-sharpen their knife with.

I sharpen all of my knives by hand.

Just my 25 cents :D
-Nick-

http://www.wheelerknives.com
 
Here's what I do. I sharpen last and it scares me to death every time! I'm deathly afraid of a little slip that would mean a disaster. I think from here on in I will sharpen before finishing, even, although that's going to mean a lot more blood being spilled in the shop! :eek:

Anyway, I have tried slack belt (really close to the idle wheel on my Coote, so it's pretty stiff), platen and on the wheel. I think the slack belt was the best edge, but it was harder to keep ripples out of the edge because of running the edge of the belt a little harder than the middle. I like the wheel best as a compromise. I put the edge on with the wheel, then I clean it up with a Lansky diamond stone, then I use my Sharpmaker. The way I see it is that my hand skills will be better for the final edge than the belt, anyway, and a lot of people own Sharpmakers, so they can touch up the edge exactly as it came to them. Seems to work!
 
I'm with Nick.:D

Here's what I do. I sharpen last and it scares me to death every time! I'm deathly afraid of a little slip that would mean a disaster. I think from here on in I will sharpen before finishing, even, although that's going to mean a lot more blood being spilled in the shop!
Click to expand...

Buy a roll of masking tape, apply it the blade,then sharpen the edge.

if you slack belt sharpen make sure you have a fresh belt, old belt more friction more heat..... Ray Kirk taught me that one
 
FWIW... Here's what they do at one of the "premier" knife production companies located somewhere in Idaho. Mind, they are into mass production, so, speed is of the essence. The knives are sharpened edge up on the wheel of the belt grinder using what I call micro pressure. Basically it's just the weight of the knife's edge gently resting against the belt/wheel as it turns. After applying the primary bevel and attaining a nice burr the knives move to a Kratex wheel to start the edge "polishing" process. (This step is done edge down.) This removes the scratches from the grinding belt and creates a mild convex edge. Finally, the blades are polished on a hard felt wheel until they will essentially shave your face. (Also done edge down.)I wish I had a photo of the guys arms that work in the grinding room.... It's a rare occasion that they have any stubble on their arms let alone any lengths of arm hair. Every knife is inspected for it's ability to shave hair. There was one guy that came back from a 2 week vacation of sorts and I almost didn't recognize him with all of his arm hair :) They use S30V for most of their blades which is extremely abraision resistant, so, if you're using anything less resistant to abraision you could probably get away with going from a very fine belt straight to the polishing wheel.

Like Nick said above. If you use a method that can easily be duplicated by your customers it will save you a lot of headaches down the road. I can't tell you how many knives and how much semi-negative publicity this company has taken due to this fact. A very common theme of concern was what angle the edge was at so that they could use a sharpening system to replicate the factory edge. Well, each guy tried for a certain angle but they were applied by hand and by the time the edges were on it was convex. Sharpening systems put on flat bevels. Couple that with a very abraision resistant steel and you can probably guess how frustrated some folks get trying to "duplicate" the factory edge.. The shop would sharpen their knives for free but most customers didn't live in town so they would have to mail in their daily user and be without it for a week or so. Yet another source of frustration. See where I'm going?

***Here's where I have to say how dangerous sharpening edge-up on a grinding belt is... It's "f-ing" dangerous. Accidents happen! One of the guys I worked with who had been doing this for about 10 years had a blade ripped from his hands. It made a nice 1/2" deep gouge in the wheel before it let loose, bounced around, cut two of his fingers deeply enough that he spent several hours at the emergency room determining if there was tendon damage and getting sewn back up. I was forced, and I mean forced, to "learn to sharpen" this way, otherwise I would have learned to do it a different way.***
 
You must log in or register to reply here.
Back
Top