Epoxy issue

Wayne Bensinger

Well-Known Member
Good morning all,
Seams I have a bit of an issue with a knife I just completed and was hoping for some input from anyone who'd be willing to help.
I recently came home from work and while getting out of the truck with way to much in my hands, as always, I dropped the new hunting knife I had just finished handle end down, right on the blacktop driveway. Needless to say, I saw red. So I start to inspect the G-10 handle and of course there's a couple of small divits and bruises on it, but nothing I can't easily remove.
Then I notice that both of the brass inserts between the bolster and the G-10 were popped loose and one actually fell out in my hand with a little help from my finger nail.
Here's a bit about the knife to help with any thoughts you guys may have.
440C, 304 s.s. bolsters, .080 brass insert between bolster and G-10 handle material, full tang. I'm using the 30 minute epoxy from Mid-west Knifemakers Supply. There is no mechanical bond between the brass and any other portion of the knife, just the epoxy bond. The bolsters are pinned and the G-10 has bolts.
I sand all surfaces to be epoxied with 80 grit first and then clean them with alcohol and assembled the handed, and I used a lot of epoxy. Everything gets wiped down with the alcohol rag to clean up the squeeze out. Everything gets clamped together for two days.
Never had this type of thing happen before, but had a couple of initial thought. First, I wonder if I should not be using the alcohol or maybe I'm using to much of it? Small parts and seams may be getting to much around them and it ruins the bond.
Second, I had heard that epoxy should only be used for up to one year, after that the hold power is greatly compromised, never new if there was any truth to this so I kept using it, my epoxy is at least two years old.
I know there's someone on this forum that will know exactly what went wrong and I hope there's enough detail here to get a good idea of my problem.

thanks, Wayne
 

EdCaffreyMS

"The Montana Bladesmith"
Early on in my career, I had epoxy problems that required me to replace handles on about a dozen knives. At that time I had been using Devcon "5 minute", and "2 ton" epoxies. I caused me to do a great deal of investigation/research on two part adhesives. Here's what I learned.....

- Almost ALL of the commonly available 2 part epoxies are chemically engineered to have a shelf life of not more then 6 months, and are also chemically engineered to last, after mixing for no more then 5-7 years! Sounds crazy doesn't it? That information came straight from a chemical engineer at Dow chemical. His way of explaining it was.... "My job depends on selling epoxy, I am never going to design a "glue" that lasts forever."

-Very few of the 2 part expoxies are actually "water proof". Some are "water resistance" at best, but most have little to no water/moisture resistance....even those that say it on the label(s).

The TYPE of alcohol your using could be having an impact too. If it's anything other the denatured, there's residue being left behind. Personally I keep both Acetone and Denatured Alcohol in the shop for cleaning purposes, and use both. I commonly do the initial "cleaning" with Acetone, then blow it off with air, and repeat with Denatured Alcohol.....and ENSURE it's COMPLETELY dry and blown off with the air hose before assembly.

Personally, after I had those "epoxy issues" and did a LOT or research, I change my adhesive to the original Brownells AcraGlas. It has a 10 year shelf life, and a guaranteed hold life of 50 years..... those are the best numbers you can find for any adhesive we could use for knifemaking, and since making the change over 20 years ago, I've never had a single issue related to it's use.

OK, all that having been said, if I understand correctly, you tried to epoxy the brass directly to the steel without any type of mechanical attachment/assistance? If so, that's not a good choice of how to do it. Attempting metal to metal bonds are simply taking a huge chance of things coming apart. The situation you described of the sudden, hard impact is a prime example of a situation where just about any adhesive WILL NOT hold. I doubt even AcraGlas would hold in that situation. I would say it's rather lucky that it happened while the knife was still in your possession, versus having sold it, and have that happen to a client.

In this situation, my opinion is that the chosen methodology is as much to blame for the failure as the adhesive. My advice would be first...take a long hard look at the adhesive(s) you use for knifemaking, and adjust accordingly. Secondly, rethink the methodology, and any time there is a metal to metal joint, use some type of mechanical attachment in conjunction with the adhesive.

A major consideration that I've come to understand over my years of Knifemaking...... If something can go wrong with a knife, it will. By that I mean that you have try to anticipate that people who buy/use your knives are going to do things to them/with them that you would literally roll your eyes at....but for the most part they wouldn't think twice about it, and they will be shocked/appalled that a knife didn't hold up to something that most knifemakers would consider a "stupid move". In my experience, I have to think in those terms when I design/build a knife.....otherwise it will become a regret at some point in time.
 

Wayne Bensinger

Well-Known Member
Thanks Ed, I was hoping someone with your experience would chime in, I appreciate it. You pretty much backed up what my thoughts where, both issues should be easy to fix and I have a thought in my mind that I may be able to save these brass inserts as the customer really likes them, I may just need to reshape the handle a bit and repolish. Not a real big deal considering the facts as they are now.

Wayne
 

KenH

Well-Known Member
Wayne, Please allow me to say I've the greatest respect for Ed and I KNOW myself, I will NEVER achieve half the knife making abilities Ed has. Ed's comments on surface prep is spot on, surface prep is VERY IMPORTANT.

Ed and I have been "round 'n round" about this epoxy bond life in the past, with me taking issue with his "chemically engineered to last, after mixing for no more then 5-7 years!". I lived for many years in the marine world where epoxy is used in many different ways and I'd NEVER heard of this 5 to 7 year bond life. Imagine boats falling apart after 5 years. I'm NOT talking about the 5 minute epoxy you buy on hardware store, but "real" epoxy.

Here is a link where Andy of BladeBond epoxy discusses surface prep, shelf life, and bond life (he'd never heard of that question before either). It's a long read, and Andy does focus primarily on his product (he's been in the epoxy for over 30 years), but his comments do apply to epoxies in general.
http://knifedogs.com/showthread.php?41296-BladeBond-Epoxy-in-stock-and-ready-to-ship!&highlight=Raka

Here is a thread where I posted responses from Raka and West Marine epoxy folks on bond life: http://knifedogs.com/showthread.php?40604-Which-epoxy-do-you-use-and-why&highlight=Raka

Please allow me to say again how much I respect Ed's knowledge in knifemaking and how much I've learned from Ed reading his comments and some of his WIP's he's posted.

Ken H>
 
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Wayne Bensinger

Well-Known Member
Thanks also to you Ken, I have a decision to make here!nsounds like it either Bladebond or Acraglass, both come very highly rated from what I've read, thanks to you and Ed.

Wayne
 

KenH

Well-Known Member
On the brass insert that's located between the bolster and scale, drill a couple of small holes thru the brass, lined up with holes in the bolster and in the scale, insert a brass pin in each hole with the pin sized to be a close fit without any slack. With epoxy between the brass insert, bolster, and scale you will have a very solid joint. I think is would be an example of the mechanical bond Ed is talking about.

For a less (but still decent) joint, with no brass pins, but allowing these holes to fill with epoxy will provide more strength than just the brass insert glued in. I normally put the brass pin in these holes to provide extra strength anytime I use a joint in the scales.

Ken H>
 

EdCaffreyMS

"The Montana Bladesmith"
No worries what so ever Ken! We all come at things through the lens of our own experiences, and in this case our's just differs...and that's OK, and a good thing. I think it gives others choices, and allows them to find solutions from different opinions, and the possibility of solving an issue in a manner that I might not have thought about. ;) (that way I learn too!) :)
 

KenH

Well-Known Member
Understood Ed - and I do agree with all find solutions that work good for "us", and sometimes they will work for others, and sometimes not so good for other folks.

Looking forward to meeting you again at Blade next year.

Ken H>
 

J. Doyle

Dealer - Purveyor
I think the main issue, far above all else, is that there just isn't that much of a bond on a piece that small. And you're putting it together pretty tight, I mean....that's an area that you don't want to see any glue lines. So you probably squeezed most of the epoxy out anyway. I think the issue was probably compounded further with the alcohol and it's wicking action. There's a chance that it wicked down between the bolster/spacer/scales and weakened the bond of the little that was there significantly.

Ken listed good ways to go about this in the future. Personally, I would (and have, a few times) pin those little spacers in. That way they're never coming out.

If you have trouble with the pins, even some holes drilled in your thin spacer that would let epoxy pass through from one side to the other would help quite a bit. And the edges of the holes would give the epoxy something to grab on to.

I really like a slow cure epoxy for the extra advantage it offers in clean up. I use g-flex and it sets up in 2-3 hours depending on some conditions. But there is a pretty good window of time where it's not runny and wet but not fully hard yet either. It's sort of gummy and pliable. And you can wait for that window and peel away anything that oozes out easily with a razor blade or toothpick or whatever else fits and remove the excess completely dry.

Usually I have 30-45 minutes where the epoxy is in this phase and it makes dry clean up a breeze with no solvents or cleaners that may affect the bond of the epoxy.
 

Wayne Bensinger

Well-Known Member
Thanks John, I'm working on set as we speak and I know I'm gonna have better results. Your right thought, those tiny pieces are hard to work with, especially to drill pin holes into!

Wayne
 

NEILYEAG

Well-Known Member
I see there is Acraglas Bedding and Acraglas Gel. What is the correct product? Also BTW, a client of mine in the states has put me on to a special epoxy that is used in golf club manufacturing. This is suppose to be the product that they use to bond the driver heads to the shafts. Durable, obviously shock resistant and no issues with moisture. I am trying to run down some of this stuff for some other assembly that I am doing with stainless steel and Titanium components. When I get the details I will post. Or maybe some of you guys know it already.
 

KenH

Well-Known Member
I think it's the bedding version which is a very good epoxy and is used by many. Most any "good" epoxy will work just fine, BladeBond is perhaps one of the best as it's designed especially for knifemaking. G-flex is just fine also. I've also used Raka with success.
 

John Wilson

Well-Known Member
I'm just about finished with my G-Flex. Are you guys happy with the Blade Bond? I want to give it a shot so long as the consensus is positive.
 

John Wilson

Well-Known Member
thanks Ken. I've been wanting to buy some since they've been so supportive on the forums.


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C Craft

Well-Known Member
Don't know why I haven't seen this thread before but here goes!!

Google "Glue Wars, knife making" There has been two very long tests done on the issue. Here is a link to the 1st Glue War, http://www.bladeforums.com/forums/showthread.php/337043-Glue-Wars-the-battlefield-is-set

Here is a link to the 2nd Glue War, http://www.bladeforums.com/forums/showthread.php/337504-Glue-Wars-2

There is a lot to read but I will give you my consensus of the war. The right glue/epoxy is somewhat about choice IMO. However the glue wars tend to single out some they consider a winner for a multitude of reasons.

Cleanliness is next to Godliness this becomes apparent. I will clean with Acetone but when it comes to final clean-up, I go with 90% rubbing alcohol range, you can get it from 90% all the way up to 99%. https://www.google.com/search?q=90%...me..69i57.390571j0j7&sourceid=chrome&ie=UTF-8

When possible I like to give the epoxy a ruffed up surface and if possible will riddle the back side of bolsters and handle material to let the epoxy flow from side to side and the drill holes allow for pockets side to side, for the epoxy to set in!!

I never use old epoxy I have had sitting for a long period of time. I don't like the fact that it has been opened to the air a multitude of times. Air exposure to the raw ingredients is not good idea, IMO! So I try to set my mix stuff up where it can be used and capped immediately after pouring ingredients are poured out! If it is 6 months old and I haven't used it up, it it used for other projects than my knives!!

I use 30 minute working time epoxy, 5 minute has its place for some jobs but, not on most knife making!!

When clamping the idea to close out all the gaps, not squeeze all of the epoxy out. A fine line to walk sometimes.

Now to what seem to be your issue in my head as I was reading your post. That goes to what I call "shear strength". In you first post you said, QUOTE: I dropped the new hunting knife I had just finished handle end down, right on the blacktop driveway.

The impact on the handle sheared the strength of the epoxy. When I first started in this I had a maker which I trust with years of knife making under his belt and many, many, knives made. He told me pins are for "shear strength"! He went on to say most epoxies have fair to good shear strength but, under given conditions, temperature, very cold or very hot, or sometimes just the right impact at the right place, or maybe you did miss cleaning one small area before glue up and the epoxy will shear. In other words the "perfect storm effect" If you have a pin the pin helps to hold against shearing even when the perfect storm happens!!!

I ain't about to get in the middle of the guys with the knowledge and time that I don't have but,................ it all boils down to have a regimented glue up process and pins are for shear strength problems, that aren't covered under the other scenarios!! good luck and let us know how things have been going lately!!
 

Leeco

Well-Known Member
Has anyone ever used high strength epoxy that is used for bonding sledge hammer heads to the handle, thats what i use, we make alot of hammers and the epoxy is verry high impact resistant. I would like to hear somones thoughts on this


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BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
By far, good surface prep will make a marginal glue outperform an excellent glue. Acetone leaves an oily film. Use it to clean things up but follow that with denatured alcohol. Sandblast surfaces to be bonded for the best bond. At least give both surfaces heavy scratches for a better grip.
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