grinding micarta is kinda tough

R

rupsty

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Mar 14, 2013
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42
its tougher than i expected.

question: when shaping scales is it a good idea to grind on the slack portion of the belt? this is my very first knife and it seemed to create less bevels on the handle, which is what i was going for. man, it's tough to get things symmetrical and even. all the while, i'm subtracting material from the scales thinking "i don't have much room left for any more mistakes!". but it really is satisfying to see the knife take shape.

in my mind its pretty easy to make a knife. it's very hard to make a beautiful, high quality knife.
 
I use a 36 grit belt to rough, moving to a 60 grit belt when I get closer to where I want to be. I actually start by creating bevels, and then knock down the peaks a bit before going to the slack belt. Here's a few pictures I took a really long time ago:

Scales glued up:


I cut a bevel up front by the ricasso:




Cut the main bevels in the scale:




Knock down the peak and blend things together:






I still use this process for certain full tang scale constructions. Done right, and with a lot of practice, it should look something like this:









--nathan
 
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I think micarta is an incredibly difficult material to work with. It's very tough, even with fresh 36 grit belts. Burns practically instantly too, so you have to go slow. Doesn't like oil, so you have to finish at a high grit and polish for a glossier look.

G10 is cake compared to micarta in my opinion.
 
wow - silver those are great looking knives. very nice work! thanks for the input. did you profile the micarta after you glued them to the steel? they follow the profile of the knife perfectly. that would have been helpful for me to do. i just had the rectangular blocks stuck on there and had to cut/grind the corners off. what a pain.

G10 - easier huh? Hmm. I have a set of those. I'm afraid of all the fiberglass bits floating around. I do have all the protective gear be the fiberglass just freaks me out a bit.
 
I started using Micarta after the first several knives because I thought it would be easier. Turns out I was wrong! But I do like it on my personal knives because it is tough. I rough out the handle on a belt sander than go to hand sanding for the final shaping. Hard to 'sand too much' when you're doing it by hand. I also use Windex or Mobile 1 while sanding. Helps carry away the dust and leaves the handles much cleaner looking.
 
Thanks, rupsty. I shape the front of the scale before glue up. The scale profiles are ground close prior to glue up (I trace the tang on the block and grind close to the line), but there is overlap that I remove once they are glued to give the flush fit.

I also just realized, I posted a bunch of finished knives with wood scales when you were asking about micarta. Something that is nice about micarta or other uniformly layered materials is that it is easier to see if you have symetry because the patterning of the micarta gives you a reference. Here's a finished micarta scale:





This one has a different shape, but it was profiled in roughly the same manner:



--nathan
 
Use fresh belts
Use slow speed especially at higher grits
40 grit is nice for removal but be very careful as it leaves deep scratches
I like Zirconia belts for roughing out Micarta, 40, 80, 120, 220 then by hand or with higher grit belts.
Yes Micarta is tough to work with and grinds slowly compared to any other handle materials I know of, Paper Micarta seems to grind the slowest
If you are seeing burning slow down and use a new belt
You need plenty of fresh air even with a respirator

Good luck!
 
nathan-

Can i ask what you're using to glue your liners together?
 
Early on I used a two-part epoxy from USA Knifemakers. However, after having some seperation issues, I switched over to acraglas. I have stopped using vulcanized spacers all together as they have too many issues and now use ultra thin G10. Regardless of material, I recommend drilling multiple small holes through the liners to allow the acraglass to communicate from the tang all the way to the scales. When possible, try and use a fastener (i.e. corby bolts) instead of just pins to give more mechanical security.

Daniel, good points. I typically go up to 400 on certain scale shapes, whether wood or micarta and then on to paper by hand. For years I did all of my scale shaping on a running-balls-out Girzzly 2x72". I still do some scale roughing on it. It runs really fast and has no speed control. I had to learn to use brief contacts and fairly rapid motions to shape scales without burning. Also, the slack belt will yield much less in the way of over-heating or burning your scales. However, the platen will scorch it in a second.

--nathan
 
In addition to slow speed and sharp belts, a couple things about micarta:

I like to keep a compressed air line with a blast tip by the grinder. Micarta clogs belts stupid fast, but compressed air works better than a belt eraser to clean them out. Blast air at the belt while it's running. Also, air blast is a good way to cool pins down fast if they feel too hot when you are shaping the handle.

In response to one of the OP's original questions, I don't feel that slack belting as that useful for handles- maybe just a bit, with higher grits like 220, to blend any rough spots from shaping. Excessive slack belting can lead to raised fasteners, or low spots in the grip material behind a guard or bolsters. It also does not remove material very efficiently. I prefer to do almost all of my shaping and sanding on 8", 4", and 1" wheels, mostly vertically, just keeping the handle in constant motion to avoid unevenness. Most times, any blending that might remain to do, can be accomplished at 400 grit with my wood/eraser hand sanding block.

That's just my way, though, you'll discover what you like best.
 
Salem, one of the first comments that I ever heard about the KMG rotary platen attachment came from Jerry Fisk. He said that it cured a lot of the "evils"associated with slack belt grinding handle material, especially when it came to exactly what you mentioned about fasteners.
As for Micarta, it is the SMELL that gets me.:eek:
 
I've only used micarta once so far, and I used a pneumatic tool called a dynafile. Its kinda like a mini hand held belt sander. It made very quick work of it using a 60 grit belt. They are expensive, a little over 400 bucks. But I just saw something very similar in a harbor freight flier on sale for 30 bucks. It was electric and used slightly shorter belts. But I'd be willing to bet it'll work great for most.
 
I aspire to those scales... sadly I'm on a file only diet so frustration sets in rather quickly. Thank you for sharing this with me, it's good to know that I was on the right direction (I my start with thinner scales though)
 
It also depends on the type of micarta/phenolic you are using. The old vintage Westinghouse stuff is tough as nails and can be a real bear to sand and grind. Modern paper micarta has a lot higher phenolic content and is considerably harder to grind than modern canvas micarta. My speculation is that they modern manufacturing process uses less resin and lower pressures during manufacture... There are substantial differences in density and quality across OEMs. Also keep in mind that there are dozens of different commercial grades of phenolic laminates out there - and their suitability for knife making is all over the map.

And "backyard micarta" isn't phenolic-based at all - it is akin to an epoxy-based cotton G-10...

Generally, I have found that wood rasps and Japanese carving files work the best for me when shaping (as opposed to 36 grit belts). Gives a bit more control, too. I use a slack belt for smoothing out contours, then finish using hand sanding up to 1500/2000 grit. Micarta doesn't generally need a top coat, but I almost always give it a coat of Ren Wax for beauty's sake.

TedP
 
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