what grit?

D

dalr753

Joined
Jan 5, 2012
Messages
77
Hey guys I was just wondering, when using the stock removal method of knife making. Should you use the most abrasive grit for the grinder, such as a 36 grit belt for the general shaping? or maybe a 50grit?
 
Bigger grit removes steel (and flesh) faster. I started with 60 grit when I first started making. It removes material quickly, but not so quickly that mistakes weren't recoverable. It's also not near as intimidating. I've been doing this for a while now, so I use 36 grit belts to remove metal quickly, getting the bevels ground to about 75% of the finished height before switching grits. Then I slowly work the grind line up with each grit. A good rule of thumb is that each time you advance in grit, you should roughly double. The progression might be something along the lines of 36 - 60 - 120 - 220 - 400.

--nathan
 
Unless I'm working on something really thick and need to knock a lot of steel off the sides right way, I bevel and taper with a 50 or 60. 36 leaves crazy deep scratches that can haunt you later when you're working on thin stock - but it sure makes rough profiling go fast. :thumbup:

I do not agree that it's necessary to step through every grit available when grinding. That's just a lot more belts to buy and more time spent changing them. Lately my progression has been profile with a 36, drill, then bevel and taper with 50, clean up with A45 and do a quick hand-sand lengthwise at 220 to check for deep scratches. Usually there are a couple, so I'll do a few more light passes at A45 (roughly 320 grit) before handsanding to a pre-HT finish.
 
I use a 36 grit if it is close to 1/4" thick. If not or after im about 3/4 of the way I switch to a 60 grit to 95% done then a few passes with a SHARP 120. After that Ill hand sand with 120 and 220 then heat treat. I didnt use 36's till after a few years cause if you don't lay it perfectly flat and one edge of the belt hits first it can leave a nice size indention. Now Im more comfortable and Id liek to think better and seem to do fine with them.
 
Thanks, for that , James. I'm looking to try a new approach in belts for my grinding. I have those belts new. I certainly won't think it was a poor idea if it doesn't work for me. I guess this is all pre heat treat ? Frank
 
I profile and bevel with a 36 grit. Profile at medium speed, bevel at my slow speed (step pullies). After that I go 160 trizact then heat treat.
 
That A45 is a very good belt. I gave it a test run on a blade tonight and was pleasantly surprised what it would do on some heat treated stainless Damascus. I do have to reach out more not for speed but for quality results in the belt grinding area. Frank
 
Frank Niro said:
Thanks, for that , James. I'm looking to try a new approach in belts for my grinding. I have those belts new. I certainly won't think it was a poor idea if it doesn't work for me. I guess this is all pre heat treat ? Frank
Click to expand...

Yeah, so far I do all my grinding pre-HT. I don't see any reason the same technique wouldn't work after HT just as well... I learned that tip from a post by Ed Caffrey, and as I recall he was talking about grinding his forged blades after HT to get rid of scale and clean up the bevels.

The 3M Trizact CF's are pretty sweet. You can get 'em finer (A30), with the same type of "structure", too.
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