Hard wood Handle problems

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Dillon.s

Joined
Mar 29, 2017
Messages
12
Hello all this is my first post on the form so plz give a guy a break if I cut threw any red tape.

so I’m looking for some wisdom and guidance on hardwood handle construction and am hoping to get pointed in a better direction then where I’m at now.

so the issue I am having is that after I get a handle all together and sanded, I’ll say about 2-3 weeks later it seems that the wood on one side flex’s/curls and pulls the liner away from the tang of the knife, but never the separates wood from liner. This only seems to happen on the knives I use g-10 liners on, all the fiber liner knives seem to hold. And it usually separates on the top on one scale and on the bottom of the other, these are full tang knives FYI. So this leads me to think when I cut a block in half and turn the insides to the out side for a book Matched look , the natural grain of the wool wanting to flex/crown is causing the top and bottom separating issue. But ya just wounding if anyone else has had this same issue and found a solution to this problem any insight would be greatly appreciated.

and a lil info to let you guy know what I’m working with. I use a wide array of hard/natural woods bacote,rosewood,zebra,cocobola,Vera wood,ziricote and more. I use g-flex epoxy and I rough everything with a 120grit before glue. I mostly use corby bolts as my fasteners and I use a danish oil as my finish on the wood, also I do drill holes thru the tang and in back Side of scales to make voids for epoxy

I thank you for any help and constructive criticism

thanks,
Dillon
 
Pics would help... Host them on another site, then import them here. Or just post links. We really need pics to get any real idea of what you are talking about.
 
Did you use Colby bolts or similar?
I learnt my lesson after my first batch of knives
 
that means the wood was too wet( or too dry). it should be between 5-9% moisture. it will curl or change shape as it comes the
domestic moisture level. you can buy moisture meters to measure. voids for epoxy and corby bolts will not help.
 
KlqFW
https://images.guru/i/KlqFW
Kl9Lg
https://images.guru/i/Kl9Lg

Hope these work

and yes I use corby bolts

and does this mean if you put wood scales on and they are between 5-9%, that they can continue to dry and drop bellow that range and curl? And is this just a draw back to using natural woods?
 
Hi Dillon,

natural wood can move. Wether its totally dry or not. Thats just what it does.

looking at youre pictures an reading your posts, I think you might also clamp youre scales to tight. If you do this, all the epoxy is pushed out between de tang and the scales. This happens faster with g10 because its solid.

can this be the case.
 
I'm perplexed by this 5-9% MC. Say you are making a full tang kitchen knife, attach the scales at that moisture content using all the best practices including fasteners. Even if you seal the affair with multiple coats of something (TruOil, or others) won't the scales slowly absorb the moisture over time and start to swell, etc.?
So, I am thinking that if you start at ambient MC and and then seal, the changes shouldn't be as drastic?
I've also read that pinless moisture meters don't work well on thin wood.
If anyone has a recommendation of a brand and model, I would appreciate some input.
Scott
 
Drill some holes in that G-10 . That way the G-Flex can bond through from wood to liner to tang & wood to tang. I also have holes in the tang..Your wood is to moist. You want it below .10% and I let it sit around in my shop for Months to years after that. You want the wood to climatize to your area..
 
What if the shop is moist (basement shop) and then the knife goes to normal humidity surroundings?

Also there is no way to know what moisture in the client's or knife receivers part of the world is?

Regardless, isn't it awkward that the wood would move this much after being finished and then also lift up the g10 with it? I also think it might rather be some g10 and epoxy problem or too tight clamping as already brought up?
 
I think there are two big hints here to allow us to focus on what is going on:
1) This only happens when dillon uses G10 liners
2) the separation occurs between the liner and the tang (not between the wood and the G10 liner).

assuming everything is suitably roughed up before gluing (btw - I would go rougher than 120 to rough up - more like 60 grit, or maybe even 30 or so .... and REALLY rough up with circular patterns - dont be shy about it), I would wonder about cleanliness of the joints?? G10 will diffuse some resins to the surface over time - making a joint potentially fail at a later time, even if it seemed secure at first - and the joint to the metal will be the hardest one to maintain adhesion. how are you cleaning the surfaces prior to gluing up? thorough cleaning using a clean cloth or towel with at least 90% isopropyl - better yet something like acetone, is needed. and dont forget to really aggressively rough up all surfaces.
 
Cushing H. said:
the separation occurs between the liner and the tang (not between the wood and the G10 liner).
Click to expand...
I'm not sure this is an important distinction that necessarily points to the reason for failure is the cleanliness of the steel/liner interface (I'm not saying it's not, either). Isn't it possible that the failure is here merely because the thin G10 can flex with the wood, whereas the steel can't?
 
weo said:
I'm not sure this is an important distinction that necessarily points to the reason for failure is the cleanliness of the steel/liner interface (I'm not saying it's not, either). Isn't it possible that the failure is here merely because the thin G10 can flex with the wood, whereas the steel can't
Click to expand...
I did not mean to say that cleanliness (and maybe roughness) IS the issue - I am only raising it as a possibility.

There are two joints here. with stresses present, failure would tend to occur at the weakest joint (thought experiment: consider if the joint between the G10 and tang were so incredibly strong one could not imagine it failing. Even if the G10 is flexible and "could" flex with the wood - it would not, because that joint to the tang would keep it from flexing. In this situation, if the wood flexes, if anything would give, it would either be the wood breaking, or the joint between the wood and the G10 separating. The fact that the joint between the G10 and tang fails says it is weaker than the other joint and causes (in my thinking at least) one to focus on that joint and ask what is making it weaker (especially when the OP says this does not happen with non-G10 liners).....
 
Dillon.s said:
and does this mean if you put wood scales on and they are between 5-9%, that they can continue to dry and drop bellow that range and curl? And is this just a draw back to using natural woods?
Click to expand...
. no, not in my experience. the 5-9% is where they settle to in most domestic environments and should remain stable. SS369, the 5-9% is the typical reading woods settle to, they wont continue to absorb moisture because they are acclimated to the surroundings. if you live in the amazon, or a desert, you will probably be outside of the 5-9, this is the content of most domestic environments. or you can use properly stabilized wood, and not worry about it. i try to.. in my experience properly stabilized wood reads 0 on the moisture meter, and sinks in water. i usually keep my wood scales for 2 years before i use them. i use a $39 moisture tester with 2 pins you stick into the wood from woodcraft. if your shop is in a damp basement, do not store your handle material there. i learned this stuff from cabinet maker forums, they do not like their joints expanding or contracting.
 
Since g10 is fiberglass clothing in epoxy resin it is going to be fairly temperature stable and very moisture stable as far as dimensions go. Wood on the other hand, especially non stabilized wood, will move. Wood will usually move less than 2% along the grain and between 4 and 12% across grain depending on moisture and variety of wood.

Try gluing (epoxy) the g10 to a slab of the wood the thickness of the final grips and set it on the back edge of your workbenches or where ever you store your knives. I suspect in a weeks time you will see the layup starting to warp. try using some of the liner material other than g10 if this occurs.
Jim A
 
Yes I have read about having a glue starved joint and I think maybe this is the issue. As when I glue up scales only use a simple and small spring clamp, but when I glue to the tang I rly snug down the corby bolts and some times put one end in the vise. So maybe it is being clamped too tight as well, yes I think going to a 30-60 grit rough up would also help. I have two more I plan to glue this weekend so I will ensure I

1. drill in backside of scales thru g-10 to ensure all layers are exposed to glue
2. Rough all surfaces with 36 grit
3. Clean tang with acetone before glue up
4. Not crank down corby bolts

Thanks all for the tips and insight on this
 
Dillon.s said:
when I glue to the tang I rly snug down the corby bolts
Click to expand...
when I have used Corby's there are times where I have clearly seen the handle material away from the corby's (especially between the bolts) move away from the tang (creating and gap and potentially failed joint). I always use multiple spring clamps on the sides of and between the corbys to control this warp and bring the handle material into contact with the tang. Might this be what is happening in your case?
 
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