why not sharpen on a belt grinder?

C

cap'njake

Joined
Aug 15, 2016
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So I keep seeing people say don't let anyone sharpen your knives with a belt grinder. Why is this? most knife makers sharpen on a belt grinder as do factories. I got myself a kalamazoo 1x42 not too long ago and I have to say that I can put a fantastic working edge on a knife in a minute or two. I understand the concerns of burning the edge but as long as you are careful there isn't a problem. So why do people get all worked up if you mention a belt grinder?
 
Belt grinders are fantastic. It's all about the operator. Most 5 year olds shouldn't be driving Honda Accords around town. Bad things would happen pretty often. People with no sharpening skills and/or no ideas about heat treat shouldn't use belt grinders on knives. People with skills can drive Honda Accords with no issues and use belt grinders on knives. It's all about the operator.

Brian.
 
I think belt grinders have their place. I like to remove the least amount of metal, using the Edge Pro or Wicked Edge. I have had knives to sharpen that would have taken an eternity with those. The Work Sharp Ken Onion Edition, esp. with the blade grinding attachment, saved my sanity. The Harbor Freight 1x30 has helped, also. The belt grinder can be sooooo helpful. I'd just rather use a more conservative method if I can.
 
tiguy7 said:
Belt grinders. We call them handle makers. They wear out good knives too fast. They work great on flea market knives.
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Totally.
When I can take a ceramic ULTRA FINE . . . mind you . . . Spyderco triangle rod to one of my properly profiled knifes that isn't shave sharp and get it to hair whittling with a few passes . . . which is about where I always sharpen.
WHY IN THE HELL ! ! ! . . . would I want to take power tool with significant horse power and noise to do the same task ? ? ?
Well yah if the knife isn't properly profiled, and many are not from the factory, and the blade is way too thick behind the edge . . . then I would maybe . . . use this "big production monster" ONCE to reprofile it and then NEVER AGAIN.
Even if I get a chip or two I'm going to use a bit coarser stone by hand or in a guided system to get the chips out.

Belt sander = nuclear bomb to wipe out an ant hill.
Why would I do that ?
And yes I have a few belt sanders for other metal work NOT KNIFE SHARPENING.
Nah dude, nah.
 
Many times I have had people ask me to re-sharpen a knife for them that has clearly been done in the past on a BENCH grinder! :eek: What a train wreck that is!
 
Im new on sharpening systems and I believe IMHO after reading and reading that belt grinder stick you on power tools. When you occasionally have in a place without power how could you sharpen a blade?

Of course it's very faster than by hand sharpener or guided sharpener, but in reason of that you must take care about heating the blade. It can affect the heat treatment. And take care about do not grind off a lot of material from blade.

Another reason is that belts can made a convex edge instead a V edge. I don't own a work sharp. I own a belt grinder (planer) for wood and I use it only if I want to set a new bevel on a old blade.
Back side the belt there is a board that ensure it's really plain.

By hand teaches you a lot about feeling the steel, patience and control/pressure.
The guided system teaches you about how perfect a bevel can be even if it's not a factory bevel, patience and control/pressure.
But if you have care, for reprofile a new bevel I believe it's a great choice.

I own a Spyderco Tenacious for maybe 7-9 years and it's very ruined at bevel (by hand tried). So this year a friend told me about jig and it's amazing. I don't have the same skill that everybody here in forum and sharpening is not my main job but I hate bad service.

Some people born to play piano... some people born to play golf... some people born to sharp by hand.

Sharpening a blade is a beautiful and meticulous ritual.
 
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If I could only have one sharpener it would be a belt grinder. They work great for all types of sharpening. Yes even for a quick touchup, think leather belt.
 
It's like any tool--if you don't know what you are doing, things can go south in a hurry. Assuming you do know what you are doing, try a leather belt with a little jeweler's green rouge on it in a grinder and you may never strop on leather by hand again.
 
Go on YouTube and search for "ruined knife sharpen" or something of that nature. Then grab some popcorn and watch videos of the glorious destruction of beautiful blades and most likely how the video creator fixes them. Many of them are sad because it's usually a nicer production or mid-tech.
 
Not too long ago, I dropped a friend off to pick up his car at a high end auto shop. There I saw examples of "great" driving... for example, a quarter million dollar sports car, still displaying a temporary license plate, that had been wrapped around a cement park bench.

Belt sanders are like that. Take the time to learn, and they're a great tool in the toolbox. But, buy a HF sander, stick a 120g belt on it, make your $200+ knife your first experience, and like the driver of the above example... I'm sure you'll be saying how terrible it is.

You can ruin a knife on just about anything. Hand a new sharpener an XXC diamond stone... and watch what happens. There are examples in this forum of people with quality guided devices, probably one of the "safest" ways to sharpen... mucking up a blade.

I've never had a belt grinder mess up a knife. OTOH... I have messed up a knife on a belt grinder. Big difference. I've also fixed many knives, that were pretty much unserviceable... that I wouldn't have otherwise bothered with.

After watching people "ruin" knives on YouTube... go back and watch those who, with a light touch and steady hand, put an edge on a knife that most here would envy.

Too many people have demonstrated that with a bit of practice it can be done, and done well, to refute any argument that it will do little more than ruin a knife. IT won't... you might. Practice.
 
Wowbagger said:
... Well yah if the knife isn't properly profiled, and many are not from the factory, and the blade is way too thick behind the edge . . . then I would maybe . . . use this "big production monster" ONCE to reprofile it and then NEVER AGAIN.. .
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If one uses a belt system to reprofile, one may it find easier to maintain the newly-created edge using the same belt system.

I've reprofiled several new-from-the-factory blades for the reasons you mention. I've done so using the WorkSharp Ken Onion + Blade Grinding Attachment to create acute convex edges. Using the same setup to maintain those edges makes life easy, since all the important factors which determined the apex geometry during reprofiling are maintained during routine edge maintenance.

In many cases, I find all that's needed to refresh an edge is a few light stropping passes on a linen belt charged with polishing compound. I believe one reason this is effective is that the stropping is being done in a manner which closely conforms to the existing convex edge geometry.
 
I have been trying to lower the bevel of my Cara Cara. Mind you, it is 8Cr which theoretically should be easy.

Went with coarse 180 (or 120?) stone, then moved up to Taedea diamond 360, 600, and then my usual DMT 1200, 8000.

Couldn't get it sharp to my liking cause the other one that I didn't thin down but merely following factory with Taedea 600, DMT 1200 and 8000 is wickedly sharp. It seems the apex keep 'crumbling ' everytime finished, or so I thought. Tried edge leading high angle pass, pushing burr to one side with wood, another high angle edge leading pass, etc. seems to eliminate what I thought was the burr, but it kept feeling rough on one side.

Suspected a bad HT, but keep trying. Suddenly it worked. The culprit: a tenacious & stubborn burr on one side from the first stone. I thought I have removed it at earlier stage of progression. It took me several sessions over several days.

If I use belt grinder (which I don't have), that blade might become a stubble and I'd never learned the patience and that lesson on the burr, could've easily written off as bad HT.

TLDR: due to the high rate of removal, very critical to know what one's doing.
 
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Chris "Anagarika" said:
... due to the high rate of removal, very critical to know what one's doing.
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Yes, indeed!

Things I do to help ensure I know what I'm doing include:
  • I use two small inexpensive Ikea gooseneck desk lamps as work lights for the belt system. I position one on each side of the grinder, aimed at an angle to highlight the edge apex. When a burr forms, it's usually easy to see as a thin bright line on the edge apex -- a line which had not been there moments ago.
  • I use a stereo microscope to inspect the edge periodically. A critical component of this setup is a ring light which offers the ability to control the direction and intensity of illumination. Light coming from all directions (i.e., a full ring light) will not highlight edge details very well -- but if the light is directional, and the direction is appropriate, details like burrs, scratches, and unsharpened regions become very visible.
 
My belt grinder has a variable speed motor, I seldom run it very fast but is still way quicker than by hand. For sharpening I like to set the bevel with 120 grit and either microbevel it on a stone and off it goes, or overgrind through a progression of stones. Even if using a progression, it is pretty easy to flatten the edge out from the belt and saves a lot of work.

If I didn't have any way to slow the belt down I would probably use it less often, or at least I wouldn't run the grind all the way to the edge before switching over to stones. Not because of heat concerns but for burr removal and possibility of taking off more steel than needed.
 
HeavyHanded said:
My belt grinder has a variable speed motor, I seldom run it very fast but is still way quicker than by hand. For sharpening I like to set the bevel with 120 grit and either microbevel it on a stone and off it goes, or overgrind through a progression of stones. Even if using a progression, it is pretty easy to flatten the edge out from the belt and saves a lot of work.

If I didn't have any way to slow the belt down I would probably use it less often, or at least I wouldn't run the grind all the way to the edge before switching over to stones. Not because of heat concerns but for burr removal and possibility of taking off more steel than needed.
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Same with mine, I can slow it down to a crawl and do quite often and it's also water cooled... I like to think if it like a modern day/new school Japanese water wheel :D
 
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