Making hex head holes in knife handles

Joined
May 16, 2002
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475
Ok...I'm stupid....how do you guys make the hex head bolt holes used on some of the micarta handles? I was told by someone they use a cherry hot bolt sunk into it....naaaaa...no way. ??:confused:??
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The only way to cut those hexagonal holes that I can see is with a mill or a power mortising machine that has a hexagonal cutter that surrounds the bit.
 
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Guys, my guess would be some type of industrial size mortise & tennon machine,or possibly a CNC machine set up with a 1/32" or 1/16" drop down bit. As many as they would have to produce (time = $$$$ ), I would put my money on a CNC.
Great question by the way . . . ( round peg in the "square" hole ) . . . . :)
Be safe.
 
I've been wondering the same thing.
With a piece of wood I was able to cut the hole to the across-the-flats diameter of the nut and press it in with my home-rigged press. That worked nicely. Then I attempted the same thing with micarta and absolutely *nothing* happened. A hot nut is a very interesting idea... I'm sure the Ka-Bar scales you pictured are done entirely via some sort of CNC process, so that's probably out of the picture for most home craftsman.

-Daizee
 
I think that they are machined in by those that have a milling machine or filed in as coleslaw mentions for the rest of us. I did a quick google search for Hex Hole Mortising Bit and couldn't find anything. Not saying they aren't out there, just that I couldn't find it with my limited Google-Fu:o If some one knows of such a mortising bit and where to find them please let us know
 
I had to ask a little more on the "Hot Bolt" way. The person I spoke to said he chucked a long bolt (8 inch) of the size hex hole he wanted into his drill press (no power). He then torched red hot it while in the chuck and plunged it into the micarta that was clamped below it to the desired depth. He then "cleaned it up with small flat files.
Mmmm....Ok...personally, I see this as being a huge mess with plastic "hairs" everywhere after you removed it but.......I dunno...thoughts (?).
 
CNC milled. I dunno how the hot bolt would work. I don't think it would end up to pretty though.
 
I'd drill the correct size bolt shank whole and then put the hex blot in the whole. Draw the outline of the bolt head with a #2 pencil and use a very small and very sharp, like razor sharp, chisel. Should not take long and a chisel will give you good clean cut lines. Works on wood should work fine on Micarta as long as its sharpe enough to cut and not just crush the fibers. As a side note I've used garage sell lfat tip scerw drivers to make chisels before. The standley brand has a nice hard tip but others will work. Make sure you square up the sides of the blade. Most have an outward taper. If you don't garind the sides flat you'll damage the hex shape of the whole you're making. You could even grind a mechanical stops on both sides for depth control. Donald
 
I like the drill-press hot-hex idea.
I don't see a problem with hairs - if you're already shaping the micarta it's just a tiny bit of finish sanding.
Though I think I would counter-sink the flats-diameter of the nut first so that only the very perimeter touch the material, and only minimal melting would occur.

I may try this, perhaps even later today and will post a pic if so.

-Daizee
 
Don't waste your time on the hot bolt plunge...my curiosity got the best of me and I had to "try" it....HA....what a BS line of advice that was:grumpy:. It never plunged into the micarta, just made a burn mark. I think the CNC way is it. Fortunately I found a very small scrap piece to experiment on.:) I think I'll save some time and $$ and buy round Torx head bolts!
 
Works awesome.
This is a little piece of test micarta in which I'd already drilled a couple ofholes for 10-32 bolts, counter-sunk at 3/8" with a spade bit. I tried pressing a nut into them as worked well with wood and got nowhere - barely even a mark. Both counter-sunk holes in this piece were identical when I started.

The hot-nut method (oy) works great. I'd recommend using a 2" threaded shank as this will let you get the nut far enough away from the drill head so its easy to heat (used a basic propane plumbing torch), and also allow some of the bolt to protrude through the nut as a pilot into the hole to ensure perfect alignment.

The slag from the melting sanded off in moments. The slag inside scraped out with a couple casual strokes from a cut bicycle spoke that happened to be on the bench. Obviously do this before you start your shaping and finishing work if you can.

-Daizee

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Works awesome.
This is a little piece of test micarta in which I'd already drilled a couple ofholes for 10-32 bolts, counter-sunk at 3/8" with a spade bit. I tried pressing a nut into them as worked well with wood and got nowhere - barely even a mark. Both counter-sunk holes in this piece were identical when I started.

The hot-nut method (oy) works great. I'd recommend using a 2" threaded shank as this will let you get the nut far enough away from the drill head so its easy to heat (used a basic propane plumbing torch), and also allow some of the bolt to protrude through the nut as a pilot into the hole to ensure perfect alignment.

The slag from the melting sanded off in moments. The slag inside scraped out with a couple casual strokes from a cut bicycle spoke that happened to be on the bench. Obviously do this before you start your shaping and finishing work if you can.

-Daizee

IMG_20110612_152614-small.jpg



IMG_20110612_153311-small.jpg


IMG_20110612_153021-small.jpg


IMG_20110612_153005-small.jpg


Well....yup. I tried it this way and got the exact same results. Very cool. I guess I didn't play with it enough! Good job, Daizee! You might have just opened up another great process!
 
Not me, you brought it up!

I've been stalled on a micarta handle for a knife for about two months due to this problem. Recently finished 3 more while waiting. I wanted to do exactly the same thing - use the bolt/nut arrangement like on my Ka-Bar BK2, and couldn't figure out a reliable way to do it. (Note that me & chisels are NOT a reliable way to do anything except damage.)

The other major hurdle is the horrible sticky toxic dust that is created by sanding micarta. It's finally warm enough to open the doors and run the exhaust fan, so perhaps now that knife can be completed.

-Daizee
 
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Here's my attempt at doing it with the hot nut as Daizee suggested. I used a bolt and did not get the results first round- this works far better. I was quite amazed how well it turned out. This was done with a 1/4" piece of micarta, 1/4" hole followed by
a 3/8" counter sink as Daizee said. Heat the nut to a cherry red and plunge. It really did seat nicely and cleaned up very well. Sure beats spending $$
for a CNC capable mill!!

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Huh, interesting - I would have bet money that you'd just wind up with either a horrible mess or just a burn mark. Now try it with G10/G11. :D
 
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