Differences in belt grit progression?

Patrice Lemée

Patrice Lemée

Joined
Aug 13, 2002
Messages
5,703
I am curious why it seem like some people will go through every single grit possible (36-60-120-220-320-400...) and others will skip some. If I remember right even as big as 60 to 400 in one case.
Is it just personal preference?

PS: I do 60-220-400 for now but I will try to skip the 220 and also go up to 600 and see how it goes. I am not comfortable enough to grind with 36 yet except for profiling.
 
For me it sometimes depends on my moods. I do find that I spend less time at each grit when I go through a more detailed progression. Basically just a few passes per side to knock the high points off between the deep scratches, progressively working the peaks down until everything is flat.

Starting with 36, I almost always go to 60 before moving up as 36 is so aggressive. From 60, I sometimes go to 180, then 320, then 600.

--nathan
 
I usually rough in with a 36, refine the bevels on an 80, and then go to 120 or 220, then to the granite for hand-sanding. I can see why I might want to use a 50 instead of a 36 to rough in a blade from thinner stock, but why one would use it between 36 and 80, I cannot guess.
 
You can make the big jumps better if hollow grinding. Harder to do flat grinding. Size of the blade makes a big difference also. Small blade I can skip, big blade (10-12") I can't and after 120, I need a new belt per grit, per each side.
 
Since I have just recently come to the wonders of using an actual belt grinder, I use 36, 60, 80 then 220 to finish off. After that its all hand sanding to 600 before ht, then back to the belt at 120 for the edge (I did that after all hand sanding on the first couple... back to start) then hand sanding again to where ever I want the finish to go. maybe as I get better i will skip the coarser grinds 60 and 80 and go from 36 - 120 hehe.
 
Steve Johnson goes from 50 to 400 on his video. He's hollow grinding on an 8in and 3 inch wheel. he then uses a worn 400 grit cork with green compound, and it looks like a mirror when he's done.

I tried this with flat grinding, and got limited results. (of course I'm no SR Johnson :p)

The finish I like, and is easy for a n00b like me to get is 60, 120, 220, 400, and super fine green scotchbrite.

I've gotten advice that I can get the same finish as that with less belts. Maybe 50, 180, and a regular fine blue scotchbrite.
 
Metallurgical polishing I go 60,120,220, 400,600,800,1200,2400, 15 Micron diamond, 3 Micron diamond
Your mileage may vary, but that is the most effective sequence for quickly eliminating the scratches from the previous grit
-Page
 
Patrice Lemée;8997665 said:
:eek::eek::eek:
How much does that comes to per blade?
Way too much $ for poor me in any case.
Click to expand...

Time is money....... You have to act like belts are free or you will spend way too much time and effort trying to straighten out what you messed up with dull belts.

I know it hurts..... My fanny draws up every time I have to reach for a new belt.

Robert
 
If you go in small steps you get much more life out of each belt and you work much faster because you are only removing small amounts with each grit
-Page
 
Pat,

Using belts seems a hard thing to swallow at first. It took me awhile to figure out when a belt is ready to retire.

It would seem that a belt that still has a rough suface texture is good to go right ? IMHO thats WRONG. When finishing bevels the belt has to be SHARP or basically in brand new condition.

My experience tells me that I get approximately two passes on each side of the blade on a new 220 J-flex on a tall flat grind. If I'm not happy and don't have a "perfect" 220x finish at that point I either need to go back to 80 and fix something or get a new 220 to finish with.

When makers say to use belts like they're free it's not just another funny saying, LOL.

I've recently taken that advice to heart and end up with a bunch of used belts laying around with alotta life left in them for things OTHER than grinding the bevels.

I've been doing my hogging with a 50x Blaze that IS a dull belt and produces crappy results but keeps right on removing steel. I go to about 85% with this belt then use as many 80x j-flex's as it takes to get to finished dimension.

It's mentally rough going through alot of belts but I feel my grinding accuracy has improved quite abit and the difficulty and time of hand finishing has been drastically reduced due to a much better finish on my blade before going to hand sanding.

Time is as they say MONEY. If you can use 4 400 grit J flex belts and have a nearly perfect 400 machine finish you spent around $13.50 to get from 220 to 400. I go over that finish with a 600 grit cork belt and start sanding at 400 by hand.

At least for me I feel like I saved myself hours of hand sanding by using those belts.

I'm glad Don mentioned his belt use (thank you Don !) as now I don't feel so crazy about going through belts like crazy.

-Josh
 
My recommendation has always been to double the grit (approx.) each step.
That may look something like 36-80-120-220-400-800-1200-2500-6000
 
I know about the free thing. But I am sorry guys, 8-10$ belts at 1 per side per grit I just can't do it, not for making knives as a hobby/not selling them. And even if I sold them, that would put the price way out of what people would pay for my stuff.

Don't get me wrong, I appreciate the advices just the same. Thanks.
 
sunshadow said:
If you go in small steps you get much more life out of each belt and you work much faster because you are only removing small amounts with each grit
-Page
Click to expand...


Yeah, that's my thinking about it too. I usually work in batches, so I'll run each blade in series across each grit. This also saves in belt change over time.

Right now, my most common process is mill, 120, 220, 400, HT, 400, scotchbrite. I get a pretty respectable machine finish:

http://i566.photobucket.com/albums/ss107/Nathan_the_Machinist/101410/1.jpg

I get about five knives up to 220, then probably 2-3 out of the 400.


(I looked into it, and it turns out, belts actually aren't free)
 
I try to squeeze as many grits in as possible, because I am very impatient, so if I can spend half as much time on twice as many belts, it makes it seem like I am going faster, so I end up spending more time total. and I still have big scratches that I only notice when I hand sand.
 
I jump from 80-320-600 in almost every case. and I make every belt last as long as it can. I'll use each grit step for 4-5 blades before changing. I too have found a used up 600 with some rouge on it will indeed make a nice mirror finish. ;) I do fairly shallow hollow grinds with my 24" wheel and taken it up to there makes it VERY easy to get the finished finish wet sanding with 1000 - 2500 grit on a sponge.

Jason
 
Patrice Lemée;8998391 said:
I know about the free thing. But I am sorry guys, 8-10$ belts at 1 per side per grit I just can't do it, not for making knives as a hobby/not selling them. And even if I sold them, that would put the price way out of what people would pay for my stuff.

Don't get me wrong, I appreciate the advices just the same. Thanks.
Click to expand...

I use the yellow Klingspor, in 120,220 and 400, they cost less than $4 each (I think). The one belt per grit, per side I mentioned, is for 10" and larger blades and just the fine grits. Smaller blades I can do both sides with one belt of each grit, but they are pretty much used up. In the 40 and 60 grit, I can do a few blades per belt.

Large blades; 40, 120, 220, 400. Small blades; 60, 120, 400.

Coarse grits I use; 3M-967. Fine grits, Klingspor yellow J flex.

A sharp, fresh belt will give a better result, faster. Dull belts are no good to me. :)
 
Don Hanson III said:
I use the yellow Klingspor, in 120,220 and 400, they cost less than $4 each (I think). The one belt per grit, per side I mentioned, is for 10" and larger blades and just the fine grits. Smaller blades I can do both sides with one belt of each grit, but they are pretty much used up. In the 40 and 60 grit, I can do a few blades per belt.

Large blades; 40, 120, 220, 400. Small blades; 60, 120, 400.

Coarse grits I use; 3M-967. Fine grits, Klingspor yellow J flex.

A sharp, fresh belt will give a better result, faster. Dull belts are no good to me. :)
Click to expand...


Thanks all for the info and insight. I agree, it's hard to train your brain to get rid of a belt when it still seems to be cutting, especially for those of us on somewhat of a budget. I know, if we are worried about money we never should have started grinding in the first place!:D:p Anyway, like I was saying I suffer from that too. I have piles of belts that I know I can't start a new knife on, or finish one up with, but I refuse to toss 'em because I keep thinking I'll find something to do with them at some unknown mystery point years down the road:o I actually threw one in the garbage today just to make sure it doesn't become an obsession!

Now, back to the topic. Patrice, lots of people use the yellow J-Flex from Klingspor, but like many I noticed that they are so lightweight they wear out extremely fast. They work well for their intended purpose, but damn they get used up quick. I just tried a couple of Norton J-weight belts from Tracy at USA Knifemaker. They are one step above the J-Flex as far as weight goes but they are a fair amount tougher from what I've seen so far and they are only about .25$ more per belt. If you can manage without the extreme flex of the J-flex, these are a pretty good alternative that will go farther I think.

I'm still new and have to yet to finish experimenting with different grit progressions and combos, but as it is right now I've been doing this:

60 grit Norzon - initial bevel grind
120 grit Norzon - clean up bevel, get lines crisp
100x Norton Norax (about 220 grit)
65x Norton Norax (about 400 grit)

Then heat treat, back through the Norax grits, or hand sanding.

BTW, I use the J weight or J flex belts before the Norax belts to clean up the plunge.........not that I'm any good at it yet:D
 
Thinking that it's cheaper to squeeze life out of dull belts is false economy. To prove the point, try an experiment with sandpaper and do it by hand. Make some scratches in two small pieces of steel with 60 grit. On one of the pieces, work out those scratches with a 1" section of 120 grit. ONLY use that 1" section, and work until the scratches are gone. Then do the other piece, but allow yourself to use a 1" x 4" long strip of 120 grit. I assure you, you won't get the same finish on both pieces regardless of how long you work with the small piece of 120 grit, because once the piece is spent, it ain't cuttin' no mo', and all you're doing is smearing or wasting time - or both!
 
I use the gator belts in the finer grits. They seem to dull at about the same rate as other belts, but if you run them at high speed and put a wire brush to them, it strips off the glazed over abrasive and it starts cutting like almost new again. This trick works several times, each with diminishing gains, until the belt is worn down to the backing. They work for a long time. However when grinding the initial bevels, using a fresh 50 or 60 grit Blaze seems the way to go. i try to push the 36 grit blaze belts for a while when profiling or descaling damascus but for grinding the initial bevels, the 50 are only at their best for few sides. YMMV
 
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