Belt usage on large blades

D

Don Nguyen

Joined
Oct 4, 2011
Messages
1,043
What I'm using:


  • KMG 1.5hp VFD
  • 1084 ~60HRC
  • ~9" edge length, 2.5" height
  • 0.125" thickness


  • 36 and 80 grit Cubitron
  • A65, A45, A30 Trizact Gator

I'm using up quite a bit of belts. I profile and do some bevel grinding pre-HT, but most of the bevel is done post-HT.



  • For one knife at 36 grit, moderate speed, I'm looking at 1 used and 2 new belts (Cubitron). I do a relief bevel/edge before hogging the main bevel so I don't rip out the grit. I do try to dress the belt (with a large carbide insert) when it stops cutting well, but it doesn't even cut nearly as well as new, so I just switch to a new belt to save time and frustration.

  • 80 grit is quick, so I maybe only use 1/2 of a belt's life.

  • For A65, A45, and A30, lowest speed, I use one whole belt each for a single knife. They load up and start burnishing pretty fast. I'm dressing them with a bent, worn ceramic at high speed. They just don't cut the same, and they load up really quick afterwards. I feel like I have to dress the belts too often.


Does this sound right? I feel like I'm using too many belts, but it is kind of a lot of steel to remove per knife. I'm probably doing something wrong, so any pointers are appreciated. Thanks.
 
That seems like a lot of belts to me. I have the best luck dressing my trizact gators with a stiff wire brush or file card. My trizacts seem to last forever.
 
I agree with Grazyer, the trizacts ought to last much longer than that. I also use a wire brush for dressing them, works well. The guys who say "use belts like they're free" are right, but they're also wrong, as belts are clearly not free. You may be giving up too fast on a belt. You said you switch to a new belt to save time and frustration. Ok, but the cost of that comes in dollars. I'm personally willing to put up with a little more time and frustration to keep from having to buy so many belts.
 
Jason Fry said:
I agree with Grazyer, the trizacts ought to last much longer than that. I also use a wire brush for dressing them, works well. The guys who say "use belts like they're free" are right, but they're also wrong, as belts are clearly not free. You may be giving up too fast on a belt. You said you switch to a new belt to save time and frustration. Ok, but the cost of that comes in dollars. I'm personally willing to put up with a little more time and frustration to keep from having to buy so many belts.
Click to expand...

I'll have to keep playing around with it. Next time I'll use a wire brush or file card. It just seemed they started burnishing the metal way too quickly; the A30 could barely cover one side of the blade before it started loading up like crazy. For the rough ceramics, maybe I'm dressing them incorrectly as well. Once they stop cutting well, it just seems like nothing I could do would get them to cut well again. I didn't rip out the grit; they were still there, but just worn down. When I dressed them, they cut slightly better, but still not that great, and wear down again anyways.

I think I'll have to find someone in person to show me how they grind and use up their belts.
 
Grind fast with ceramics. They like it.

They will cut more efficiently and you actually will get longer life from them.

Since you are grinding after heat treatment take a look at this video http://youtu.be/kvlKfzW12d0?t=5m28s Ray is grinding fully heat treated blanks and does it at break neck speed.
 
I'm familiar with that video, and his grinding is pretty astonishing.

I always thought the 967's were meant for moderate speeds though? I used the 977's at high speeds and they had similar results. I'll just have to keep practicing and see what's going on.
 
I use the cheaper ceramic belts in a 60 grit at high speed also. That takes off most of the steel. Then I use the gators to finish. Those gators seem to last a long time.
 
Ceramics and structured abrasives have a long life. You should get many blades from one belt. Some get 100 or more. They need two things to work right - SPEED and PRESSURE. These aren't for wimps. You have to run the belt fast and push hard. Then they will cut like no tomorrow. As they cut, the pressure shears the abrasives and creates new cutting surfaces. Go slow or press light and they just glaze over. If they seem to stop cutting, take a piece of a carborundun grinding wheel to the belt while running and it should be good as new in ten seconds ( wear a face mash and respirator).
 
Don.
One thing I noticed is that you are grinding some of your blades bottom to top. They are 2 1/2". That's about 3 times the metal to remove than when doing a 1" blade hunter with a grind of only 3/4". You are covering a huge area. I figure you are getting full use out of your belts. I have been using the 3M 36 and mostly 60 grit ceramics and go over the belts with a wheel dresser once they seem to be going down hill. I have not tried "reviving" the Norax U 100, 65, 45, 22, and 16 s I use after. I also grind all my blades after heat treat and use 100% stainless Cpm154, M390, 154CM and such. I sure like the quality of your work that I have seen. I think the finish you want requires the belts you are using. Perhaps try the grinding before heat treat. Your use of abrasive belts will become less, but other problems seem to jump in. Frank
 
James Poplin of Pop's knife supply, which is where I purchase my belts, has told me there are production makers who get a hundred blades from a single 36 grit ceramic belt, like 984f and similar quality.
These folks grind with a leverage arm so they can apply pressure to the blade. They also run 3 and 5 hp belt grinders running at 7,000 sfm.

Its the high speeds and extreme pressure that makes ceramic last so long and cut so well. He alsoe recommended the belts be tension-ed tightly.
 
Jeremy Barnard said:
What size knives are you talking?
Click to expand...

About 9" edge length, 2.5" wide, and 0.125" thick. The grind is somewhat like a convex, but essentially it's pretty close to a full-flat.

bladsmth said:
Ceramics and structured abrasives have a long life. You should get many blades from one belt. Some get 100 or more. They need two things to work right - SPEED and PRESSURE. These aren't for wimps. You have to run the belt fast and push hard. Then they will cut like no tomorrow. As they cut, the pressure shears the abrasives and creates new cutting surfaces. Go slow or press light and they just glaze over. If they seem to stop cutting, take a piece of a carborundun grinding wheel to the belt while running and it should be good as new in ten seconds ( wear a face mash and respirator).
Click to expand...

100 knives is kind of unbelievable...

I'll keep at it, with high speed and pressure. Right now I'm using my friend's KMG but it has serious issues bogging down, so I'll probably have to wait to get my own grinder to really crank up the hogging.

Frank Niro said:
Don.
One thing I noticed is that you are grinding some of your blades bottom to top. They are 2 1/2". That's about 3 times the metal to remove than when doing a 1" blade hunter with a grind of only 3/4". You are covering a huge area. I figure you are getting full use out of your belts. I have been using the 3M 36 and mostly 60 grit ceramics and go over the belts with a wheel dresser once they seem to be going down hill. I have not tried "reviving" the Norax U 100, 65, 45, 22, and 16 s I use after. I also grind all my blades after heat treat and use 100% stainless Cpm154, M390, 154CM and such. I sure like the quality of your work that I have seen. I think the finish you want requires the belts you are using. Perhaps try the grinding before heat treat. Your use of abrasive belts will become less, but other problems seem to jump in. Frank
Click to expand...

A constant battle :) Lots of food for thought; I'm not sure if I have the cajones to do a lot of the grinding before HT, especially for oil quenching steels.


Thanks for the help everyone. Looks like I just gotta keep practicing and crank up the speed on the coarse grits.

Anyone else having similar experiences with the gators loading up quickly though?
 
Oil quenching steels shouldnt make ya worry about the quench. They are usually less reactive to warping and what not then water quenching steel. I am still learning alot but will add that I use to eyeball edge thickness before the quench. I started measuring how thick it actually was and kind of got surprised how thick I was leaving it. Then came the warping once I got down to the recommended pre quench thickness.

This lead to more research and finding that
A.) Normalizations are a huge contributor to post HT straightness.
B.) The bevels have to be even on both sides. Any larger discrepencies in these will lead directly to warpage.
C.) I had to learn how to straighten blades.
 
I wanted to add but had to leave that I just last week had a new Norton ceramic belt to try that I believe will work very well for people like me who don't use a lot of pressure. Its Norton R999B in only in 24 and 36 grit sizes. I ran the 36 on 4 kinds of hardened steel and was very pleased with the results. It seems to grind better than the 3M - 36grit ceramic . It also looks like the belt will last longer. I'm already hoping they will soon release a 60. Frank
 
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On the gators, I found that high speeds glaze them qiuckly. I have a 2HP VFD KMG (what a string of letters) and set the speed very low when using the gators. I am able to get over 25 blades per belt (probably more, but I use them for other things also). Generally I use 160,100,65,45,30. I don't always go thru the total progression, depends on the final finish. I have some that have almost worn off the abrasive and are still working. I don't use much pressure either, as that seems to give me longer life and better finishes.
Chip Kunkle
 
I haven't counted, but I probably get at least 25 blades from a 36 grit cubitron II.

Trizac Gators will last a long time if used only for finishing.
 
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