View Full Version : Koa Split While Drilling

Marko Tsourkan
05-20-2013, 05:25 PM
Ran into a problem today. Koa (K&G stabilized) split right in the middle while I was drilling it. Never had wood split on me. When I look at the split, it's along the curl. When I put it in a vice and tighten, the split closes perfectly. Has anybody had a similar experience?

It really suck because I am in the middle of the project that was to be completed for tomorrow. It makes even worse that I have no substitute block in stabilized koa.


sachem allison
05-20-2013, 05:33 PM

Delbert Ealy
05-20-2013, 05:34 PM
I haven't had any stabilized wood split on me that I remember, but if it fits that close then glue it back together and proceed. The glue line should be minimal, and if you are using good glue it should be strong as well.

05-20-2013, 05:35 PM
Probably a stupid question, but is your drill bit dull and/or are you adding too much pressure on it? This could cause the drill to act more like a "wedge" and cause the split.

Dream Burls
05-20-2013, 07:38 PM
. It makes even worse that I have no substitute block in stabilized koa.


I have a few if you're interested. Stabilized by K&G and ready to go.

Burl Source
05-20-2013, 08:33 PM
What you described can happen.
Especially with really old growth or compression curl.
Sometimes there can be hidden internal flaws.
Dave saw that recently with a block of koa that looked good on the exterior.

Not sure how you hold the wood when drilling,
but if the wood is clamped to the table when drilling it can prevent slight movement that can cause the drill bit to wedge in the hole and break the wood.

If the Koa was one of mine, let me know and I will mail a replacement piece.

05-20-2013, 08:33 PM
Happened to me with several woods before also. Usually I attributed it to too much pressure, dull bits, wrong drilling speed - or any combination of those.

As for the re-gluing. I never used to do that with wood but in the end it's a resin-soaked material you are binding back together with resin. As long as the fit is perfect, I don't see any problem with that With other resin soaked materials like bakelite or reconstituted materials it works perfectly fine, just as with mammoth tooth which usually breaks and fits back together perfectly.


05-21-2013, 07:33 AM
I've had decent luck with brad point drills. They tend to wander less, especially around knots in wood, which may cause less wedging/ stresses in the wood. Stuff always goes wrong when you're on a deadline. Good luck.

Marko Tsourkan
05-21-2013, 08:10 AM
Thanks guys.

What took me aback is that I drilled a center hole and it went fine. The block split on me when I drilled an adjoining hole.

I think I had 3-4 handles on this bit only, so it was still pretty sharp. I drill in increments, to clear the chips, so no unusual pressure or speed.

All long drill bits wonder (or walk) a little bit, but I can't imagine them to wonder as much as to create a wedging pressure. In any event, this has never happened to me before and I have used this process for over 2 years now.

I drill in a press with wood held by a vise.The vice jaws are about 1.5" tall.

Here are the pics.




05-21-2013, 09:01 AM
My guess would be internal stresses in the wood being released, haven't seen it as catastrophic as that before though. Quite often with natural woods i'll take a square block, make a tang slot and the block will have moved out of square by the time i'm done, guessing the stabilisation takes some of the ability to flex out so it cracked instead.

05-21-2013, 10:53 AM
TB_London makes sense.

I'm a little concerned by people saying "glue it up and continue." I don't think I'd want to be the one wondering if my Marko knife had a hidden split in the handle.

Burl Source
05-21-2013, 02:29 PM
Marko made the right call with replacing the wood.
The crack is following the grain along a medullar ray.
Like when you are splitting firewood.
The split looks a little bit wiggly because the figure is tight compression curl.
This could happen to anyone.

05-21-2013, 02:33 PM
Yep, this looks worse than I imagined, clearly a case for the bin. Too bad, looked like a very nice piece.