What belt grits to use

B

boulderer

Joined
Feb 13, 2005
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9
I'm looking for recommendations on which grits I should be using for knifemaking. I'll be making my knives via the stock removal method and I currently have a Delta 1x30 belt sander. I can get the following grits in 1x30 size:

40/60/80/100/120/150/180/220/320/400/600

Thanks for the help.

--
Ben
 
I use 36,60,220,400,600 Buy more 220 than the rest ;)
 
I second what Brian said, although I use 120 grit a lot and very little 220 or 400. Then I hand sand after 400.
 
Ed Caffery (as I recall) doesn't use the mid-range belts. He goes from 80 to something like X45. (OK I have CRS, but it's something like that.)

I've started doing that. It seems to be working for me, but I haven't really switched over completely ... yet. It is nice because you don't have to change direction to see scratches.

I'm thinking of just using an 80 and then a few fresh 400 AO belts or something like that. The trick is getting a perfectly flat finish with your roughest belt - at least that the lesson I'm learning. If I find a divit at any grit I try and make myself go back to the 80 grit. Amazing, but if you're flat you can move up thru the grits a whole lot faster. (OK I'm a slow learner too.)


Steve
 
30-30, of course low grit belts are essential. I guess I didn't make that clear! I think I like 60 grit better than 36 for grinding blades, but I haven't made my decision yet! I use 36 or 60 more than anything, but of the finer grit belts I do use a 120 for a lot of different things.

Sando, I skipped from 36 to 120 to 400 on a few knives and the results were about the same as going step by step, to be honest.
 
I'm currently using 50 (3m ceramic) 120 (3m ceramic) 220 (3m ceramic) 400 (AO) and once in awhile 3m 15 micron finishing belts.
This works pretty well for me, but I've got a 1.5HP 2X72 grinder. When I was doing a lot of stuff on my 4X36 I started with 36 grit, and used more of the coarse grits as I worked up. It doesn't have the power, or belt speed to hog stuff off very well, so the coarse belts were pretty much mandatory. I liked to have a few steps on the way up though as the machine ran a lot smoother with finer grits. So you can fine tune a little more with each grit instead of having a lot of work to do with your final one.
I'm not real familiar with the 1X30, but I would guess the coarse belts would help. It should do better than the 4X36 though since you don't have as much friction as the big wide belt.
 
The 36 grit bets I started with didn't seem to do much more than annoy me by going flat in a few minute's time. I'm on a 4 x 36, by the way. I've found that a 50 or 60 grit to profile with is a nice, even, meditative pace. Lets you get things right where you want them, and you have good control.

I start bevelling with an 80 grit belt, and then take it to 320, and 600 as my bevels get closer to the lines I have marked on the blank itself. I use 220, 320, 400, and 600 for surfacing from 'as shipped' state (I use a lot of damascus that has been surfaced by the people I buy it from, and it seems like they just rub it between two large rocks...).

Hope this helps,

Darryl
 
36 grit belts can have such large abrasive particles that it pushes the metal away from the belt.If the metal is hard,50 or 80 grit is easier to grind the profile with.Anneal the steel and you can eat a flat grind in no time at all on a 36 grit.I go 36,(usually followed by a quick trim up on 80 to get the deep grooves out),120,220,400.I have belts and laps to 2000,but usually hand sand above 400.The old rule ,which is still a good one, was to double your grit each change, ie. 50,120,220,400,800,2000
 
D.A. Guertin said:
The 36 grit bets I started with didn't seem to do much more than annoy me by going flat in a few minute's time.
Hope this helps,

Darryl
Click to expand...

I had that problem too with run of the mill AO belts. Lately I managed to get my hands on a few zirconia or something belts. They look similar to my 2X72 ceramic belts, have a really thick layer of green abrasive on them. When they start to get slick, just run the end of a peice of scrap steel across it a few times and its cutting again. I think I'm down to my last one, I'll have to look and see if there are any markings left on it to know where they're from. I bought them at a woodworking show at a booth selling a bunch of generic tools, bits,belts etc. $2 a peice.
 
The type of grit for the type of material is important. The 977 and 967 series from 3M are very good for steel. The new gator belts produce a flat even surface on steel and last quite a while. I like the blue zirconia flex belts for handles. I like the 3M micron series for blending the tang to handle material and sharpening. I like Apex by 3M on my surface grinder. Most of these belts are high line belts and expensive; 2x72 are about $5.5 some are less. The right belt for the job is the best value. If you intend on grinding CPM steel like S30V or S60V you will end up with ceramic belts. You might start with an 80 grit 977 then go to an A180 Gator, then to and A45 Apex or Gator and it is not to bad to hand rub from that point. The outside edges of the belts stretch and are longer than the center and tend to cut a groove on either side of the platten. The Gators seem to have less of this problem.

On another note when I started I had a 1x42 machine. After grinding for and hour or two the steel platten would get so hot it would warp on cause problems with flat grinds. I had to weld a piece of .5x.5 angle iron to the back making a triangular tube, this severely limited the flex of the platten...Take Care...Ed
 
blgoode said:
I use 36,60,220,400,600 Buy more 220 than the rest ;)
Click to expand...
Right on! That's exactly how I've done it all along too, and Ben I think this is your best answer so far. You're probably going to be using A/O belts since I don't think all these other specialty belts will be readily available in 1X30 (I could be wrong, it'd be worth checking).

I finally figured out a reliable way to determine how many belts I'm really using, for future orders; I've been inventorying the belts I throw away. By the end of the year I should be able to accurately figure out the proper order for next year. One thing that's surprized me is that I've used almost as many 220 as everything else combined... I'd have thought it would be 400.

The main thing to remember is to change your belts often! As soon as it stops cutting, change out your belt. The best advice I've ever heard is to use belts like they're free. That is so true.

Good luck and have fun!
 
What I've been doing is as much profiling on my little Craftsman bench grinder because the wheels are cheap to replace and last forever anyway. Once I hog most of my steel with that, I switch to a semi-worn out 36 grit to get the profile refined, then I have been switching to a fresh 60 grit to start the blade bevel grinding. It's slower starting on the bench grinder, but it's cheap and it's not that much slower for me, so it's worth it. What I don't like about 36 grit belts is the grit blows off the belts for about a minute when I start using one and it's all over you and in your face.
 
For hogging, I mainly use either the cubitron 50 grit ceramic or the Trizact CF A300 (80 grit). I am mostly grinding S30V and D2 and these belts last waay better than the lesser varieties.
 
For profiling I use 36 and 50 zircs. For hogging 50 grit zircs. Putting the grind on the blade it's 50, 120, 220 and finish on a scotchbrite belt. I only do satin finishes.
Scott
 
And don't forget that Phil Hartsfield uses new and worn 40 grit belts for his grinding and polishing! Thats it! You can do it too! Heck experiment with 80 grit belts and maybe save deep work. I like to go from rough grinding to 240 grit then hand rub anywhere from 220 to 2500 grit if its stainless and I am sending it to HT. O1 , I used to go 60 - 80 - 120 and then hand sand to 220 for HT. Right now I am thinking , for 440 c, maybe benchgrinder, 80 grit belt grinder, 240 belt grinder and then HT then when it comes back go with new and worn 150 grit belts. I think it would be practical, tough and different.
:cool: :cool: :cool:
 
I've got 24 grit zirc belts that I hog with, they work great.

When I first got my grinder built, for the first week or so I only had 24 grit, and 800 grit belts, so I went from 24 to 800 and it did fine, but I ate a lot of 800 grit belts really fast!

It was amazing, I discovered that I could go from rough forged to ready for Ht in 15 minutes on really simple grinds, if I didn't mind using 2 800 grit belts per blade.

I should also qualify that my motor is 2 horse, and my belt moves at 5450 fpm. Some people say it's to fast, but when I make knives, it's to pay bills, not play with knives :)

I go all the way to 6 micron now, and can get a mirror finish on a blade on the belt grinder.

Tony
 
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