Handles coming apart

Noticed a problem recently with a few knives that I've been working on. The handle material seems to be separating from the steel. I noticed it with two that I was working on shortly after putting them together (a few days) and then saw it recently on one that I did a couple of months ago where it's starting to separate.

The material is G10 liners along the tang and I have been using either BSI 5-minute epoxy or JB Weld 5-minute epoxy.20220208_133446.jpg20220208_133451.jpg20220208_133509.jpg

Any thoughts on what I might be doing wrong? Is it something that I'm doing or using? Could it be something with the wood?

Thanks
 

Alden Cole

Well-Known Member
Those aren't the best epoxies you could be using, but I'd think it would have more to do with glue up preparation. How do you prepare your tang/scales for glue up?
 

jmforge

Well-Known Member
Either mix your own epoxy using the West System components INCLDUING filler or similar marine grade stuff OR buy one that has already been formulated as an adhesive, like West G Flex. If Remember that G10 is epoxy based, so you shouldnt have a problem with that sticking assuming best practices. Remeber also that if you ask some folks why they drill so many holes in their full tang, they might tell you to lighten the knife AND also so that you have some epoxy to epoxy contact. There are some epoxy types out side of the marine and aircraft industries that are pretty good and ready to use, but they tend to be specialized stuff, like the epoxy that you use for golf clubs. Before G Flex and similar stuff came out, some folks said that the stuff they sold at Golfsmith was among the better ready mix stuff that you could get for our purposes.
 

fitzo

Gold Membership
Too much heat on the tang during finish grinding the handle? Heat kills epoxy bonds and cause wood to flex.

What kind of wood is that handle? Stabilized?

Did you rough up the surfaces of the G10 prior to glue-up?

As mentioned, better epoxy. Don't over-clamp at glue-up.
 

Sean Jones

Well-Known Member
In addition to what has been mentioned above, you want to make sure both your knife tang and your handle material are absolutely flat. If not, and you over-clamp, your handle material will flex during glue-up and then start bowing later and pulling away from your tang.

Unfortunately I know this from personal experience. :rolleyes:
 

Merle

Well-Known Member
You might not be able to tell without puling the handle material off, but my first question was whether the epoxy is disbonding from the metal or the wood. If it's predominately releasing from either one or the other that could indicate contamination or poor surface prep on the material.

Although I think even if that is all good, the epoxy is always going to bond better to the wood than the metal. So if you had preload / pulled up gaps like Sean mentions, then when the clamps come off and it's unloaded if it's going to separate it will likely disbond from the metal and stay stuck to the wood.

Granted I don't have a ton of experience like most of the guys here do; I'm strictly bush league. My first knives I used hardware store epoxy but at some point stepped up and bought some Blade Bond from Bossdog's site. While I never had a failure with the store bought stuff, the BladeBond sure seems like a better stronger adhesive.

-andy
 
Last edited:
Thanks for the replies. I think I everyone hit a few of the items that I was originally thinking I was doing wrong.

My prep work mostly has been a wipe down with either Windex or alcohol to clean it up, then a lite scuffing with either 80 or 120 grit. Then I would clean again. Next was to mix the two-part epoxy, glue, clamp. Once dry it was sanding with belt to clean up and loose epoxy and start shaping. ANY recommendations on changes here would be greatly appreciated.

The wood that I used on the one pictured was Goncalo Alves that I got from Woodcraft. I've also had it on some Chechen that I bought from there and some zebra wood. I just looked at another knife that I did before this which has Gaboon Ebony and G10 on it and starting to see the same thing. From what I know they are all stabilized, but not 100% sure. Any easy way to check or confirm?

My thoughts of what I maybe did wrong is I think everyone hit on:

1. Over clamping. One some of them I know I was clamping really tight. Not sure why I did, I just did. Should I be clamping at all? If so, how tight is too tight?
2. Am I overheating the handle material when I'm grinding it or cleaning it up? There's been a few times I know that it would be warm or close to hot when touching. If this is the case, would it like be belt speed or just being too aggressive?
3. Am I prepping the materials wrong. On the two that I did take apart and redo, it seemed like the epoxy that was left was very thin and mostly seemed to stay on the G10/Wood.
4. Am I using the wrong wood or doing something wrong with the wood?
5. Is everything level/flat? I think it is or at least pretty close. I was told before that the epoxy can help fill in where it's not, but I'm guessing I was given bad advice on that from what I'm seeing.

Is there any way to fix these without redoing the handle, or would it usually end up being a handle redo?

Thanks Everyone
 
Either mix your own epoxy using the West System components INCLDUING filler or similar marine grade stuff OR buy one that has already been formulated as an adhesive, like West G Flex. If Remember that G10 is epoxy based, so you shouldnt have a problem with that sticking assuming best practices. Remeber also that if you ask some folks why they drill so many holes in their full tang, they might tell you to lighten the knife AND also so that you have some epoxy to epoxy contact. There are some epoxy types out side of the marine and aircraft industries that are pretty good and ready to use, but they tend to be specialized stuff, like the epoxy that you use for golf clubs. Before G Flex and similar stuff came out, some folks said that the stuff they sold at Golfsmith was among the better ready mix stuff that you could get for our purposes.
@jmforge I was also thinking previously about drilling additional holes because I had seen other references to doing that. Any thoughts or experience from anyone about that?
 

vlegski

Well-Known Member
Just me but scale failure means they come off..Something wasn't done right and I need to find the cause. Are you using fasteners?
 

bladegrinder

Well-Known Member
If the handle material and tang were both flat to each other first I don't see how this would even happen, there had to be some kind of warp or bow on the tang or the handle material. but even with an ever so slight bow a good glue up and clamping and those handle should have stayed in place.

In your pictures the handle material isn't separating from the tang, the G10 is. with G10 you have to be sure you've removed ALL the glossy surface for the epoxy to take, if not your essentially epoxying glass to steel which isn't going to work to well with epoxy.
the tang needs to be roughed up to so there's nothing left on the blade from heat treating.

I'm in Florida and even where I'm at I've seen temps in the 20s and 30s, tomorrow morning is supposed to be 31, I make sure to keep all my freezeables inside my house and not in my shop. even at that, before I set handles I make sure the handle material and blades I'm working on are at room temp. after glue up they go in a cardboard box and into the house.

in the end...my best guess is you've got a warp somewhere and the G10 and or tang weren't prepped good. I would tear the whole handle off, that knife is prone to future problems trying to fix it any other way.
 

tkroenlein

Well-Known Member
This is how I prep a tang. Note the fuller ground in and the two larger holes. The fuller does two things. It makes it easier to get a gap free fit, and it creates a pocket that cannot squeeze out and adds surface area for shear and peel strength.

First, ditch the 5 min epoxy. You want slow cure and waterproof.

G10 does not bond easily, nor does steel. 60 grit circular scratches or sand blast the steel. Sand the G10 until you get past the slick layer and hit the glass fiber. That fuzzy texture, even though it is very fine, offers a lot more for the glue to get ahold of (same with Micarta.)

My guess is your wood is not stabilized. As it breathes, it can change shape or twist quite dramatically. G10 doesn't. That builds a lot of tension. We've discussed that phenomenon on here before. You might be able to find it, I don't know what to search though.

A mechanical fastener like a corby bolt, loveless, or sex bolt will hold a handle on without glue. Those can solve some issues over straight pins when your chosen materials or assembly specifics don't offer ideal bonding or are prone to environmental influence. BE284A68-0296-434C-BF66-DEA5D8EF9E8B.jpeg
 

Heikki

KNIFE MAKER
This is how I prep a tang. Note the fuller ground in and the two larger holes. The fuller does two things. It makes it easier to get a gap free fit, and it creates a pocket that cannot squeeze out and adds surface area for shear and peel strength.

First, ditch the 5 min epoxy. You want slow cure and waterproof.

G10 does not bond easily, nor does steel. 60 grit circular scratches or sand blast the steel. Sand the G10 until you get past the slick layer and hit the glass fiber. That fuzzy texture, even though it is very fine, offers a lot more for the glue to get ahold of (same with Micarta.)

My guess is your wood is not stabilized. As it breathes, it can change shape or twist quite dramatically. G10 doesn't. That builds a lot of tension. We've discussed that phenomenon on here before. You might be able to find it, I don't know what to search though.

A mechanical fastener like a corby bolt, loveless, or sex bolt will hold a handle on without glue. Those can solve some issues over straight pins when your chosen materials or assembly specifics don't offer ideal bonding or are prone to environmental influence. View attachment 80198
I started doing this with mine also - drilling fewer holes and adding a fuller. I also prefer using welder's clamps to C-clamps for clamping. I feel I'm less likely to put too much pressure on with them and squeeze out all the epoxy ( I also find them quicker to put on when my hands get all sticky ;))
 

TimGinMN

Well-Known Member
My thoughts...
1. Yes, you should clamp, just not so tight that you squeeze all the glue out. Leave some in there to fill the gaps or any imperceptible warp. Maybe use spring clamps instead if screw clamps.
2. Overheating? Maybe... I have accidentally softened mosaic pins and spilled their guts by overheating when sanding handles.
3. Use G-Flex epoxy instead of 5 minute glue.
4. Heed what everybody else said. They know more than me.

There is another thread on epoxy active right now that has some good advice also: https://www.knifedogs.com/threads/epoxi.53237/#post-430725
 
Last edited:
This is how I prep a tang. Note the fuller ground in and the two larger holes. The fuller does two things. It makes it easier to get a gap free fit, and it creates a pocket that cannot squeeze out and adds surface area for shear and peel strength.

First, ditch the 5 min epoxy. You want slow cure and waterproof.

G10 does not bond easily, nor does steel. 60 grit circular scratches or sand blast the steel. Sand the G10 until you get past the slick layer and hit the glass fiber. That fuzzy texture, even though it is very fine, offers a lot more for the glue to get ahold of (same with Micarta.)

My guess is your wood is not stabilized. As it breathes, it can change shape or twist quite dramatically. G10 doesn't. That builds a lot of tension. We've discussed that phenomenon on here before. You might be able to find it, I don't know what to search though.

A mechanical fastener like a corby bolt, loveless, or sex bolt will hold a handle on without glue. Those can solve some issues over straight pins when your chosen materials or assembly specifics don't offer ideal bonding or are prone to environmental influence. View attachment 80198
@tkroenlein Thanks for the info. I definitely didn't have mine scuffed up this much, which I'm wondering could be a big part of it. I'll have to do this on the next one I do. I'm also thinking that I didn't get the G10 sanded enough.
 
Thanks everyone. I'll be taking all of this with me on the next couple. It really verified some of the stuff that I felt I was probably doing wrong. Also checking out and ordering some other epoxies.
 

Gene Kimmi

KNIFE MAKER
The last thing I do before gluing is hit the tang on a 60 grit belt and the scales on a 60 grit disc. Blow both off with compressed air then glue. With both being freshly ground, there’s no need to use a cleaner that may leave a residue. I got this tip from Karl Anderson.
Also, check out Ceccorp c-tough epoxy. I have switched to it from g-flex.
 

John Wilson

Well-Known Member
All great points, particularly the need to scuff everything. I’m also going to point to the Windex. Windex is a wonderful degreaser and I use tons of it, HOWEVER, it will ruin a glue joint if you don’t get it off your materials. It leaves a slick film of its own. So don’t abandon the Windex for cleaning the blade / tang after hand sanding but you do need to clean the tang afterwards with acetone or denatured alcohol to remove the windex residue.

The 5 minute epoxy is also adding difficulty to your process. It can begin to set in as little as a minute, long before you get your clamps on. 5 minute epoxy forces you to rush and often you’re in a state of panic before you get the handle all put together. Aside from being a poor epoxy, you don’t need that kind of stress in your life.

G-flex 650, Acraglass, or Blade Bond or any of the 24 hour epoxies will give you a vastly better bond and will give you all the time you need, and then some. A 32 ounce kit of G-flex 650 will last you an entire year of making knives for about $60 or so. We all started out with 5 minute epoxy and learned the hard way just like you are learning. Save the JB Weld for metal to metal bonds like fitting guards. It’s amazing for that.
 
Top