Making belts last

Brock Cutlery

Brock Cutlery

Joined
Jan 10, 2015
Messages
1,673
I had an experience about a month ago and meant to post it here. I'm curious what kind of millage others get.
I started grinding this gyuto yesterday, and my back was getting stiff. I had lowered my grinder about 4 inches on a new smaller bench, and I was finding it difficult to stand for a prolonged time.
So I pulled over one of my shop stools and sat down. No big deal. But the funny thing is, I could grind better! At least rough grinding.
I could hold steady so much better. I was amazed.
Then.... Well, on a 3.5mm thick blade this big (240mm) I usually go through 4 40grit belts or so. It just takes a lot of grinding and belts.
But not today!? This belt just kept going and going. I have to attribute it to my steady hold on the blade. Nothing else changed except sitting.
I was determined to see how far I could take this belt, I was so intrigued. By the time I looked up, well that blade had got mighty thin! OMG! Like just under 2mm and full distal taper.
How the hell did that happen! One 40 belt?!
 
Brock Cutlery said:
I had an experience about a month ago and meant to post it here. I'm curious what kind of millage others get.
I started grinding this gyuto yesterday, and my back was getting stiff. I had lowered my grinder about 4 inches on a new smaller bench, and I was finding it difficult to stand for a prolonged time.
So I pulled over one of my shop stools and sat down. No big deal. But the funny thing is, I could grind better! At least rough grinding.
I could hold steady so much better. I was amazed.
Then.... Well, on a 3.5mm thick blade this big (240mm) I usually go through 4 40grit belts or so. It just takes a lot of grinding and belts.
But not today!? This belt just kept going and going. I have to attribute it to my steady hold on the blade. Nothing else changed except sitting.
I was determined to see how far I could take this belt, I was so intrigued. By the time I looked up, well that blade had got mighty thin! OMG! Like just under 2mm and full distal taper.
How the hell did that happen! One 40 belt?!
Click to expand...

I have always wondered, what do people use to gauge when a belt is "done".

For me - and i'm new, so i've probably trashed decent belts and held on to shit ones, but recently i've been using a set number of what I expect to get out of them, and trying to work an equation for it. I had a brand new 50 grit ceramic belt, i used it to surface grind a knife, and cut 1 entire bevel PLUS 70% of the second side (I also broke the 45's with this belt, probably not great for the abrasives), and I could just tell it wasn't cutting. It wasn't taking metal off and I found myself dunking the blade and making no progress - so I called it done and trashed it. This seemed more scientific than just tossing them - which i've been doing a lot lately.
 
Brock Cutlery said:
I had an experience about a month ago and meant to post it here. I'm curious what kind of millage others get.
I started grinding this gyuto yesterday, and my back was getting stiff. I had lowered my grinder about 4 inches on a new smaller bench, and I was finding it difficult to stand for a prolonged time.
So I pulled over one of my shop stools and sat down. No big deal. But the funny thing is, I could grind better! At least rough grinding.
I could hold steady so much better. I was amazed.
Then.... Well, on a 3.5mm thick blade this big (240mm) I usually go through 4 40grit belts or so. It just takes a lot of grinding and belts.
But not today!? This belt just kept going and going. I have to attribute it to my steady hold on the blade. Nothing else changed except sitting.
I was determined to see how far I could take this belt, I was so intrigued. By the time I looked up, well that blade had got mighty thin! OMG! Like just under 2mm and full distal taper.
How the hell did that happen! One 40 belt?!
Click to expand...
About five years ago when i found this forum I read a lot ......New hobby for me so i was hungry for knowledge....I remember on one topic , guy was saying that he worn several belts to grind ONE blade from M2 steel . Now after five years I know that ....he is lying /probably to justify asking price for knife/ or he simple DON T know how to grind !
If you search thru my post you will find that in many occasion I mentioned that i can grind more then ten blades from steel like M2 , M35 , M42 , T1 ,T15 HSS steel ....all that with ONE 2 x 42 and 40 grit Klingspor belt !!On my 17 inch contact wheel grinder I still use first and only one for now belt/ 50x1500 ,40grit/ and i make many hollow blades............. BUT probably most here think ...............what this new guy from Macedonia know about knives and grinders :D
Look , think for a moment on industry which use expensive grinders.......do anyone really , REALLY think that they change belts every five minutes ????????? I remember watching one video on You tube ..........big plate of hardened stainless steel , over 2 m. long and over 1m. wide .Belt was / i think / zirconia ...they grind and grind surface of that plate........
Now what i think .....I USE square tube as jig to hold my blades on work rest .THAT allows me to put steady and strong pressure on belt ........I don t think that anyone can do that holding blade in hand . Of course also the factor is belt speed , I've been yelling for years here ....speed you need speed for ceramic belts .........but again,what this guy from Macedonia know about grinding steel...
Ok , enough !
I m glad that you find your way..............:thumbsup:
PS. There are only two things which are the recipe to destroy good belt .To GLAZE ceramic grains or to fracture them to FAST ....
 
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i have been sitting grinding for about 2 years since i saw claudio sobral grinding sitting down. using your knees as a moveable rest for your elbows is wonderful. was it a different brand of belt ? have you tried 3m 984f ceramic ? i get many large knives out of one belt. its more economical for me to spend $13 on one 36 grit belt and get 8 knives out of it, than to use one $3.50 AO belt on each of the 8 knives. your results may differ, everyone grinds differently.
 
4-40grit belts on one knife? Are they ceramic or cheap AO belts? Something is wrong if they’re ceramic. You’re either running too slow and glazing your belt over or you’re throwing out a belt that isn’t bad yet. Get a chunk of carbide and run it on a belt you think is worn. If it’s glazed the carbide will fracture the grit and it’ll start cutting again. If you aren’t using ceramic forget everything I just said lol
 
I am pretty new. When grinding a 210 mm chef knife from .1" stainless post HT at 62 Hrc I easily go through 2 ceramic 60 grit belts, even three. These where VSM xk870x. When they loose their cutting ability I jam a piece of hardened steel in there real good to expose new well cutting grit. After doing that 3 times the belt is done though, flat thin and fugly.
Last week I switched to Deerfoss Bora 7 and did a similar chef and one belt was enough, and there is still belt life in there.
 
Scaniaman said:
I am pretty new. When grinding a 210 mm chef knife from .1" stainless post HT at 62 Hrc I easily go through 2 ceramic 60 grit belts, even three. These where VSM xk870x. When they loose their cutting ability I jam a piece of hardened steel in there real good to expose new well cutting grit. After doing that 3 times the belt is done though, flat thin and fugly.
Last week I switched to Deerfoss Bora 7 and did a similar chef and one belt was enough, and there is still belt life in there.
Click to expand...


These sound interesting because is use the VSM. Where do you source the Deerfoss?
 
john april said:
i have been sitting grinding for about 2 years since i saw claudio sobral grinding sitting down. using your knees as a moveable rest for your elbows is wonderful. was it a different brand of belt ? have you tried 3m 984f ceramic ? i get many large knives out of one belt. its more economical for me to spend $13 on one 36 grit belt and get 8 knives out of it, than to use one $3.50 AO belt on each of the 8 knives. your results may differ, everyone grinds differently.
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John, 8 knives hardened grinding or pre heat treat?
 
Ok ... so when people say faster is better ... what does that mean? Currently I do my bevels with 60 grit ceramic , and run at about 65-70% on my VFD (ameribrade, 110v source.). I have no earthly idea of what FPM that is.... is that “fast enough” for ceramic?

(btw, per a previous thread ... I don’t so much see a belt stop cutting, as I see a more worn belt creating more heat. When I stop being able to control the heating of the edge, I stop using that belt for refining the bevel (and it then gets used for pre HT profiling or cutting in the 45 on a few new blades.).
 
DustinY said:
These sound interesting because is use the VSM. Where do you source the Deerfoss?
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I'm in Sweden, so maybe not very useful to you :) But I got them from a place in Denmark Carls.nu
The price is low at appr USD 5.50 when buying 30 or more.
Another maker who uses them said they perform as well as 3M 984F ( I have not tried those, but they are 3x the price).
 
I was careful to describe the size and thickness of my blade, but I did leave out the belt type and the steel state.
I only use 3m Cubitron belts for rough grinding. Is there any other kind? I start at 40 grit, then maybe 60 or 80, but usually straight to 120 grit cubitron. Then gator belts to finish up.

The blank was 52100 hardened at 62 rockwell prior to grinding. 240 by 50 mm.
I run my grinder at full speed. I don't know off hand the FPM. It's an esteem grinder with 2HP motor but only running on 110 so I don't get the full 2hp benefit. Not sure if speed is affected by 110 v.

I think I have been under-using my belts for years based on my latest experience. I don't think glazing is an issue, but pressure certainly seems to be. My sitting has allowed me to force more pressure.
I grind by hand, no jigs. So I think sitting just gave me a better firmer grip.
This is the knife. This thing is under 1mm 2 inches from the tip. Spine above choil was just a hair under 2mm.
When I started it was a solid 3.5mm blank. So that is a lot of steel to come off.

....I still get a chuckle out of one of my first year posts where I admitted to using like 14 belts on one blade. It wasn't that big a blade either. That is funny.

FullFront-01.JPG
 
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I use 40 grit belts for profiling and roughing in bevels (post heat treat), and they last a few knives each, depending on size of course. I have been grinding sitting down since I started, so I can't comment on the difference in longevity there. I do think I use belts for what some would consider "too long" (dull), but I have more time than money at the moment, so that just is what it is.

Would anyone be interested in doing a comparison on when we throw our belts out? Say a simple test with a belt you would normally throw out - a 10x30mm piece of hot rolled steel, 30 seconds of grinding at full speed and hard pressure, on a work rest, and measure how much of the steel is removed after the 30 seconds is up.
 
It would be interesting to put together some kind of scientific tests on belts and see if we can't figure out when a belt is really shot or not. I haven't done any grinding since that one, but I am going to go back to some of my saved 40 grits that I saved for profiling after they got 'dull' and see if there is much life left in them for knife grinding.
 
john april said:
i have been sitting grinding for about 2 years since i saw claudio sobral grinding sitting down. using your knees as a moveable rest for your elbows is wonderful. was it a different brand of belt ? have you tried 3m 984f ceramic ? i get many large knives out of one belt. its more economical for me to spend $13 on one 36 grit belt and get 8 knives out of it, than to use one $3.50 AO belt on each of the 8 knives. your results may differ, everyone grinds differently.
Click to expand...

This video?
It's interesting! Thanks for that.
 
I use the VSM’s sometimes. I have a 3 speed KMG running on 220v. I run the fastest speed and am pushing hard enough to get sparks to follow the belt and get thrown back across the top toward me about 90% of my initial post heat treat bevel.
 
Brock Cutlery said:
It would be interesting to put together some kind of scientific tests on belts and see if we can't figure out when a belt is really shot or not. I haven't done any grinding since that one, but I am going to go back to some of my saved 40 grits that I saved for profiling after they got 'dull' and see if there is much life left in them for knife grinding.
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@JTknives can make tests like that ................as far as I know he surface grind lot of steel on converted on belt surface grinder....That surface grinder can offer controlled conditions while grinding.....so we can know what ruin belt fast and what make them last long. And if we donate different belts we can find out which brands are best .....?
 
Natlek said:
@JTknives can make tests like that ................as far as I know he surface grind lot of steel on converted on belt surface grinder....That surface grinder can offer controlled conditions while grinding.....so we can know what ruin belt fast and what make them last long. And if we donate different belts we can find out which brands are best .....?
Click to expand...
Really good idea (I’m serious). Not gonna happen ... JT needs to make a living/profit from other stuff. We will all probably need to accept we will live in ignorance :-(
 
Cushing H. said:
Really good idea (I’m serious). Not gonna happen ... JT needs to make a living/profit from other stuff. We will all probably need to accept we will live in ignorance :-(
Click to expand...

Yeah, I wouldn't volunteer someone else, but I'd be willing to participate if we can figure out a meaningful test.
 
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