Cracked handle

Justin Presson

Justin Presson

Well-Known Member
Well it was bound to happen at some point I guess Im just glad it was one of mine and not a customers.
This knife I finished in August. I have taken it hunting with me a few times and the rest of the time it has set on my bench in my basement workshop. It actually had another flaw and I disnt let it out of my shop so blessing in disguise I guess.

Yesterday I was cleaning and decided to move it to the gun safe and noticed this large crack.
This is natural Bocote. Why do you think it cracked....just shrunk due to the low humidity? The tang feels proud all around too.

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That's an odd crack. I would have expected to see it split along the grain. But it looks like it follows some of the other grain pattern as well. Was this scale cut on end grain or along the grain axis? Also if the tang is proud the wood wasn't seasoned enough and is actually beginning to shrink, that may also be the reason it cracked like that.
 
could be related to the pin combined with wood not being completely dry. wood is expanding and contracting around a pin that is not moving.
 
It was end grain cut or whatever you call it. I have had this wood for about 2 years not sure how long it set before I got it.
 
Ty Adams said:
Is it bias cut? With that large of a crack my guess would be the material wasn't dry yet.
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Justin Presson said:
It was end grain cut or whatever you call it. I have had this wood for about 2 years not sure how long it set before I got it.
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I think that's the reason. If it was cut on the end grain, (my two cents) and not completely seasoned (dried) is the reason for the crack. I don't think end grain, unless it is stabilized would be good for knife scales. But it does make amazing grain patterns.
 
I have bocote blanks and have not made handles because even the blanks have cracks and they move and warp(I have played with finishes on them and wax seems best)...I think it is the brand of wood...not anything you have done. Ask others that have used it? I might use mine for inlay as the wood is beautiful...but I don't think I will make handles.
 
I've used Bocote and haven't had any issues, ...yet.
I just did a search and came up with this, so it adds to the seasoned/dry explanation, perhaps.

Drying & shrinkage:

Bocote is not easy to dry. It is dimensionally stable once dry, but readily develops checking and end splitting. Average reported shrinkage values (green to ovendry) are 5.0% radial, 7.4% tangential and 11.6% volumetric.
 
Humidity levels play a large part too, if you built that knife in July with high humidity and used REALLY tight pins, once the humidity goes down the wood is going to react, that's what makes the tang proud. it's like making a knife in July in Florida and sending it to Arizona in August, that handle is going to move unless its been stabilized or Ironwood or another species of wood that is dense and somewhat dimensionally stabile.
 
The way it cracked and pulled away from the tang makes you wonder if something didn't happen during your outings. Is there a possibility that you set something on it while hunting? Maybe sat on it while it was in your back pocket? Something that would cause the tang to flex causing a small crack. Now that the pressure has dropped because of your cold spell the wood pulled away from the handle and pin.
 
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Justin Presson said:
It was end grain cut or whatever you call it. I have had this wood for about 2 years not sure how long it set before I got it.
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End grain makes for a pretty pattern, however......... not always a joy to work with!

opaul's research says why-
Bocote is not easy to dry. It is dimensionally stable once dry, but readily develops checking and end splitting. Average reported shrinkage values (green to ovendry) are 5.0% radial, 7.4% tangential and 11.6% volumetric.

bladegrinder said:
Humidity levels play a large part too, if you built that knife in July with high humidity and used REALLY tight pins, once the humidity goes down the wood is going to react, that's what makes the tang proud. it's like making a knife in July in Florida and sending it to Arizona in August, that handle is going to move unless its been stabilized or Ironwood or another species of wood that is dense and somewhat dimensionally stabile.
Click to expand...

And Steve nailed in on the head. Fl. probably has more humidity, bar none. I have seen dried lumber move as much as 3/4". I once floored a trailer with PT Pine. It had been in the sun for weeks, before I used it. I cut it for length and bolted it down the trailer and my son is helping with the trailer almost a month later. He says geez Dad, you cut that one a little short didn't. The board I had cut full length to fit it on the trailer was now 3/4" short of touching the same frame I driven it into a month before that! None of the other boards had shrunk near that much.

Sometimes it is the nature of the beast. Not all wood reacts the same!!! Some woods really do need to be stabilized. Stabilization will help immensely with movement on a knife handle!! I suspect you pulled the rivet a hair tight or the hole was a tad tighter, or some little thing that would not have been noticed at the time but, for whatever reason the wood began to move a little, the pin put pressure on the wood and that is why it failed at the rivet!
 
I've seen it happen to knives that were put in a safe with dehumidifier rods for a couple weeks, the tang goes proud and sometimes pins will too. after taking it out and putting it where the humidity is high it will go back to 'almost normal'. which is usually a bad sign because it's more than likely going to do it again sometime in it's life, probably in the hands of someone other than the maker.

I use raw wood like lots of others do but I prefer to use stabilized wood as much as possible just for this reason.
 
I agree with Darrin. It's one of those "live and learn" things. I would venture to guess that like me, most have learned this the hard way.
 
Remember that folder I did a wip on a while back, had Dogwood scales cut on a bias? It was fine in the shop, but I took it in the house and the next day it cracked just like yours. It had those cross rays just like yours. Humidity changed and caused the wood to move is my guess.
 
I'm sitting here racking my brain trying to remember if I've ever sent a knife out with an end-grain handle..

Ugh. I supposed if I did it will come back to me sooner or later. Lesson learned!!
 
breaking the "form follows function" rule of design...or as I reworded for knife making...."Practical precedes pretty"...usually WILL bite us somewhere...lol. The "Ooooohh Pretty" temptation is always a hard one to set aside.
 
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