Discoloration around pin holes

S

Simon C

Joined
Feb 7, 2019
Messages
2
Hey Guys,

Looking for some advice on how to prevent imperfect hole edges around pin holes on a fixed blade I'm working on. I'm not sure if its the handle material, pin material, or my method that is causing the problem. I'm using stabilized maple, but I also tested walnut with similar results. Pins are 316 stainless 1/4" diameter. I've successfully drilled clean holes by using a sharp drill bit and tape but when I install the pins and grind them flush I inevitably end up with discoloration around the hole where small flecks of metal have embedded into the wood grain. I've tried scrubbing them out and I also tried using superglue around the perimeter of the hole to try and reinforce it but similar results. Any one else have this problem, any ideas what I'm doing wrong?

https://imgur.com/Uxtc66a
https://imgur.com/LMmoUlq
https://imgur.com/KSty31V
https://imgur.com/TrI8JZl
 
Cut the excess pin off with a hacksaw flush with the wood. Work very carefully and slowly using the grinder when shaping/finishing the handle. If you grind the pins down you will burn the epoxy and get a dark halo.
 
What those guys said.

Also it looks like your drill is not making exactly round holes.
 
I was going to suggest heat being the culprit. Looks like others beat me to it.
 
Heat is most of the issue as others have said. As far as fit goes, get a reamer and a drill press to help get a more perfect circle. Some drill bits seem to drill triangle shaped holes.
 
TIPS:
Cut the scales thicker than needed. An exter 1/16" or more each side makes the tearout on the surface less of a problem.
Drill the holes with a wood bit designed to make round holes. Brad point is a good choice.
Test the pin stock to see if it fits right. Get the size stock that just slip fits with moderate pressure.
Using a tapered reamer is also a good way to get a round hole in wood.
Tint your epoxy with epoxy dye to match the wood. It doesn't need to be perfect, but tan/brown epoxy will show less on walnut that clear. On ebony, and black micarta, black epoxy makes excess hole space disappear. I keep red,blue, green, tan/brown, black, and white dye. With these I can blend a close match to most woods.
Use 24 hour cure epoxy and let it cure 24 hours.

Once the handle is cured, cut off excess pin stock with a hacksaw and use a file to bring the stibs down to the wood. Sand slowly and use a fresh belt ... especially on stainless steel pins.
Corby bolts also help eliminate some of these problems once you get the process dialed in.
 
Problem Solved! Thanks for the quick advice. I think my holes weren't round, as was suggested by Avigil and Matt R. I ran some tests including a brad point drill, drill press and drill press vice. I also used a more aggressive belt and didn't let the pins get too hot when grinding which meant about 5 seconds of pressure and then let them cool for a minute. The result was a close to perfect line around the hole.

https://imgur.com/a/m3hulI2
 
Matt R said:
Heat is most of the issue as others have said. As far as fit goes, get a reamer and a drill press to help get a more perfect circle. Some drill bits seem to drill triangle shaped holes.
Click to expand...
Most of black one ,yes .Shiny one like cobalt drill bits are precision ground and they make perfect circle :thumbsup:
 
Perhaps cobalt bits make good holes in steel, but all twist drills make out of round in wood. They grab and tear the grain along one direction (x), and shear cut it on the other(y).
 
Looks like a combo of some tear out with the hole and/or pin stock being out of round slightly. If I'm doing 1/4" pins or larger, I'll normally just use a corby pin with a properly sized counter bore, as it gives a much cleaner hole as well as a mechanical advantage. For smaller pins, I always use a tapered reamer and lightly peen the heads of the pin stock.
Like Stacy said, it's a good idea to leave just a little bit of extra thickness to account for any minor tear out or a slightly boogered peen. Another thing I'll sometimes do is glue the scales together and drill the holes, then use the "inside" as my "outside", if that makes sense. In other words, there's rarely any tear out in the middle where the scales are glued, so after I drill the holes, I'll knock the scales apart, clean the glue off, and use the glued faces as my new outsides.
 
I would avoid 316 SS. In my experience it work hardens very easily. That might be part of the overheat when pins are ground down.
 
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