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  #61  
Old 03-20-2005, 05:27 PM
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tmickley tmickley is offline
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Lane, I recall testing Devcon 5 years ago and it held up OK. I hadn't tested since. It may have changed formula but I'd suggest to any knife maker now that they avoid it.

Ray, you are right about seemingly testing for sheer only but we're trying more than that. Sheer stress - whacking the snot out of them - is the only way to accelerate failure in our meager testing shops. I've cycled through the heat furnace three times, the freezer at least as many and the dishwasher once. These are all different for heat, cold, metal expansion contraction, hot detergent soaking ultimately tested by sudden shear shock - ala the big whack. Steve, who's short movie on testing should be nominated for an Oscar (technical division) I'm still giggling about, testing by vibration, I am testing by impact.

My current test is under way, soaking for two hours in water and then straight to the freezer. This is stabilized wood that has not been sealed so it should have soaked up quite a bit of water. We'll see how that works.

Couple other tests to report. You might recall I was amazed at Loctite 324 Speedbonder load holding 100lbs. I glued up another test piece to verify the results and get a picture this time. The #### stuff did it again. It held 100lbs, the metal started to bend, held for 45 seconds (as I was trying to get the camera into position) and ultimately failed again but I still claim it held 100lbs. It lasted about as long as last time. No picture, again and this time the metal was really bent which is way cool. I did notice that the mechanical force on the test piece being bent changes from shear to peel force and that may account for the failure. In any case, the 324 is amazing stuff for how well it holds. I still think it is too expensive but if it comes out on top, it is what I will use.

I did the same load test with gorilla glue and it failed at loading 50lbs which is the weakest of the bunch so far. This is very disappointing but not neccesarily a deal breaker. I'm not sure two pieces of metal being glued together is fair for this adhesive that requires moisture to kick off. Even though I put plenty of water in the joint, it still didn't look quite right when examining the sheared joint.

One concern with gorilla glue was expansion and the need to tightly clamp to keep the scale from pushing away from the tang (or whatever). I glued some up and put three big clamps on a full 5" strip of metal to wood. When it cured, I ground down the edge along the entire length. There is no visible glue line. (I'll post a pic later) I had a concern that tightly clampling this stuff would some how change how well it held so I banged on it harder than any piece so far and with more thumps than any piece so far and it didn't budge. I continue to gain respect for the polyurethanes to use with metal/wood material handles. I would not use it for metal to metal or metal to micarta/g10/ivory.

I will be retesting the gorilla glue with metal to metal and then a sandwich with liner material soaked in water in between. That should provide the moisture it needs to kick off. I have some wood/metal curing for round 2 if I ever make past round 1. I also have some golf shafting epoxy curing for the load test.

If nothing else we have learned and confirmed that surface preparation is the single most important factor in a sucessful glue up. I understand this maybe a premature leap of logic at this point but I'm going to include my last 5 years of glue ups and aircraft composite studies prior to that for my opinion. I'll remain open minded if testing proves other wise, but I'm fairly confident it won't. I know some adhesives will outperform others but I will bet any one nearly any amount at this point, the best adhesive will not perform as well with poor or even mediocre surface preparation as any of the appropriate, 'average' adhesives would with excellent surface preparation.


Debate and investigation on the best surface preparation process may end up being the most important learning we get from this entire process.

Any one have any opinions? (now that's funny and I don't care who you are...)
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  #62  
Old 03-20-2005, 06:22 PM
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Hmmm... After reading through these results I am very interested.

At the begining of this post I had mentioned that I would like to try a test with an autobody adhesive. I have done a metal to metal test in the past with this material. If you think the Loctite was amazing... hold on to your britches!

When we tested this at the shop we used 2 frame clamps on a frame rack. One end being stationary the other end hooked up to the pulling post. We made it past 1 1/2 tons, yes TONS, before anything happened. The bond did not break. The metal tore! Honestly if I wouldn't have been the one that applied the adhesive I would have thought this was a bogus test. If you think I am BS'ing you.... I'm not. And I don't work for the company either. If you care to learn more about this adhesive here's a link. I'm going to see if I can find some actual figures as to how expensive this stuff is.

http://www.lord.com/Default.aspx?tabid=1150&pid=5

Chris Nilluka

(Update.... I did some checking around for prices. It seems to be around $30.00 per 7.6 oz. It looks like you would have to buy extra tips and the gun as well. Unfortunately, or fortunately, the human factor is taken out of the equation. You have to have to tips to mix it. You can not mix it by hand. And you have to have the gun. There are two guns, one hand pump and one pneumatic. For out application the hand gun would be sufficient. There's still the big problem of color. Once cured it is an ugly green color. I'm not sure if a die would ruin it or not. Part of it won't die, there are micro beads in the adhesive that are a pastie white color, but really small. So, even though this may be stronger than would ever be needed in the knife world, I don't think our customers, or our selves, could get past the color. I know there are a few other autobody adhesives that are almost as good as this one I just don't know any specifics. If anybody would like I could find out. If not, just say so.)

Last edited by chrisinbeav; 03-20-2005 at 10:28 PM.
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  #63  
Old 03-21-2005, 05:33 AM
dudeinthehut dudeinthehut is offline
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Thumbs up

This is great stuff gang! As "pure" scientific research, this testing is outstanding and, to date, has yielded what I think everyone agrees is very interesting results. Kudos.

On a practical note, I would like to see how these products or product types perform under realistic stresses as would be endured by a knife handle/bolster.

For example, the most common type of stress endured by a knife handle would be created by prying something or being dropped, even from a considerable hieght (for blades used by tradesman or building construction workers, perhaps). Under those conditions, the handle would most likely, but not always, have the support of multiple pins, which would create yet another axis of support perpendicular to the main "glued" surfaces. This strengthens the bond exponentially against the kind of forces that are replicated by the tapping test.

By no means am I suggesting that the tapping test is irrelavent. Quite the contrary--All things being equal, the strongest adhesive, as revealed by the tapping test, will also be the strongest adhesive in a pinned handle. I only wish to point out that even the least of these products as tested, may serve perfectly for a lifetime and longer in a well pinned handle (and I'll bet someone reading this can testify to as much).

I would be very interested in seeing a prying test to see how far a given bar can be bent before adhesive failure. Not even pins could prevent that (I wouldn't think).

Again, gentlemen, do not take this as a critisism. I am impressed by the scientific method you have chosen to employ and I, like many of the others who are "glued" to every addition to this thread, am grateful for the research you have undertaken (at your own expense no less). Thank you.

Drive on!

Andy
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  #64  
Old 03-21-2005, 07:21 AM
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After soaking 2 hours in water and freezing 3 hours and then some more beatings while frozen, there was........no failures. I'll try thumping them again when they thaw out and then it's back to the dishwasher for a few cycles unless I can think of something else.

Chris, I'd sure like to see more on that automotive glue.

Andy, I think your point on prying is good one. I'll see if I can some how work it in but I think the metal test coupons I am using are too thin to pry with. We'll see.

If any of you have ever been deer hunting and seen some one split the rib cage or pelvis with their knife, you would agree the sheering whack tests are exactly field conditions. I understand there are no pins holding the scales in place but they don't take the entire shearing stress, the adhesive takes some also. It doesn't take much movement to crack lose a scale. I've also been camping where I've seen knifes hammered on to split something.
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  #65  
Old 03-21-2005, 10:33 AM
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Tracy, you're getting closer and closer to proving that metal preparation is more important than brand of epoxy! Your stuff is all holding together quite well and it was all prepared the same way.

My first tests all had easy failures and I traced it back to the metal prep.

I think we're finding out there are many acceptable choices if done right.

Can I recommend a test for you? How about boiling in water. The temp of boiling water is under 212f. Yes, many of the wood samples might split, but the epoxy shouldn't come apart. This isn't a far-fected test either. While camping many of us will stir a pot with a knife. That heat will travel right up the steel.

Andy, you and Ray bring up the same kinda issues. Also, Andy, you mention peal strength. That's not listed in the specs of any glue's data sheets except the Loctite commercial stuff. Here's what I'd like to see:

After we get some more test results, someone should take a few of the better epoxies and try different construction methods. But with all the different ways to attach handles, we should lower the playing field to just a few epoxies.

Steve

PS I'm getting more and more excited about U-05FL (and Xtreme). It doesn't have the shear strength of epoxy, but it is very strong and remains flexible. It will allow some give while materials expand/contract. It holds up extremely well to the impact tests. If it holds up to thru environment tests, it just my be my choice for slab handles.

One more time: My belief is that the best choice is not necessarily the strongest. I'm refining my criteria, but right now it's this:

Holds very well (shear strength, impact/vibration)
Is not brittle
Does not crack materials that expand/contract differently than steel
Withstands freezing and heat
Works with a thin glue line
Doesn't introduce wild colors
Easy to work with/ apply


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Last edited by SteveS; 03-21-2005 at 10:35 AM.
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  #66  
Old 03-21-2005, 11:09 AM
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Wouldn't you want water resistance on that list? Or are the remaining qualifiers about equal in that respect?


As for reducing the number of epoxy brands, I agree. The question that I would have comes from the "sage" advice that I've always heard regarding epoxy: "Always use the long curing time epoxy because it's stronger and more water resistant than the quick cures."

I've glanced at the results in this thread and it isn't clear to me if the distinction between slow and fast cures has been a criteria.

It's quickly becoming apparent that many things we have assumed to be true about adhesives were just urban legends. Keep up the good work!


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  #67  
Old 03-21-2005, 12:19 PM
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Quote:
Originally Posted by TexasJack
I've always heard regarding epoxy: "Always use the long curing time epoxy because it's stronger and more water resistant than the quick cures."
That myth is gone! Take a look at Loctite 324 - stuff has a one minute work time. The advice is still appropriate as a rule of thumb. But it's not a be all-end all rule. Probably helps when comparing store brands. My E-120hp has a 2 hour work time (that's what the 120 means). It's the strongest epoxy they make. So the rule fits when comparing to similar epoxies in this particular line. Then I have U-05FL. That stuff is a whole different compound. It has a 5 minute worktime. It doesn't have the shear strength, but better water resistance.

The West Systems stuff I have has a 15 minute worktime, but I'll bet is stronger than 30 minute DEVCON.

Go figure.

Steve


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  #68  
Old 03-21-2005, 05:23 PM
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To simplify, my learning is: A great surface preparation is much more important than the adhesive being used. I'd say this is easy to challenge and I'd expect that statement to be challenged.

Steve, I think your list of preferred qualities is dead on. I'd suggest some numbers on the temparature range would be -60 (been to minus 45 in North Dakota) to a high of 180 which *should* make it dishwasher proof. If it can't last through a dishwashing, it fails. I understand most custom knives would never be put in a dishwasher, but some are going to be like it or not.
I'd also add mild solvent resistance to chemicals like gasoline or kerosine. I'm not sure what other chemicals a knife might be exposed to. Maybe a farmer or military guy can pipe in here. Maybe MRE's would count as a caustic agent?

I'll do the boiling test, maybe tonight if I can get to it. I think that would be a good one and would maybe fail a couple more.

What ever is left after that is getting a kerosine soaking.
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  #69  
Old 03-21-2005, 08:39 PM
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You won't believe this one!

OK I made a new test bar, sand blasted, everything applied, waited almost 3 days, then my imact test. JB Weld was the first and only failure. Some wood stayed on the bar, but it gave up.

"How can that be Steve?"

I squished the samples with C clamps. Not real hard but harder than the other test where JB Weld won.

"What did you learn Steve?"

JB Weld is fantastic stuff, but has to remain thicker than I'd like for slab handle construction.

Steve


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  #70  
Old 03-21-2005, 08:59 PM
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unless you got a bad batch of jb weld(not if you are using the same tubes as befor) or it was just a bad mix. if those 2 things are not factors then jb weld definetly need a thicker layer.
boiling is a great idea!!
...justin
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  #71  
Old 03-21-2005, 10:25 PM
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The body count rises...



After boiling for a little over an hour (that is a highly scientific term that means about a hour or so) we had some failures. JB Weld that is supposed to be good to 300F plus took a walk. Super Glue Metal epoxy failed. There was 1/3 of a piece held by T-88 that gave up and Devcon, the epoxy we all love to hate now, had 1/4 of a piece left that fell away. The just fell off, no whacking needed. All the others were whacked because at this point they expect it and I think I'm starting to like it.

Whats left: all three poly glues. (I know, I'm sick of them too) but ALL THREE POLY GLUES, Acra Glass! (Huge cheering from this bunch), Golf smith shafting epoxy (my new favorite) and the blue marine epoxy. If you have anything that is in the water a lot and needs to be epoxied, the blue marine stuff is the way to go. If you are making a weird looking knife and need blue liners, the marine stuff is the way to go.

So, what tests can we do now? Any ideas?

So back to the poly glues. Here is that picture of a glue up using Gorilla glue. I clamped it in scientific terms again, real good. It did not expand to make an uneven glue line or even exposed glue line. There is no glue line, if you think you see one in the picture, I assure you, you do not. Does it hold? I beat the heck out of this piece, it is still holding fine.
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  #72  
Old 03-21-2005, 10:31 PM
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Quote:
All the others were whacked because at this point they expect it and I think I'm starting to like it.
I'll analyze your results later. Right now I'm laughing too hard.

Steve


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  #73  
Old 03-22-2005, 03:10 AM
dudeinthehut dudeinthehut is offline
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I think I'm rooting for the Gorilla Glue at this point! You just gotta love the marketing strategy with a name like that!

Someone tell me again what kind of a line it makes at the edge.

I also can't seem to locate the post where the heat and cold tests were done on it.

Has any one used it for leather?

Thanks guys! You should really set up a fund to help pay for this research. Hell... use it to buy something nice for your wives (who are putting up with you). Even if you want to donate it to Toys for Tots or some other charity on behalf of the knifemaking community... just take the money. We are all getting so much out of this--It just seems like a great opportunity to do something nice.

My two cents...

Andy


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  #74  
Old 03-22-2005, 08:29 AM
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those polys are doing dam great! by the way JB makes a marine version of there glue.

this is from the jb web site
"When fully cured, J-B Weld can only be removed by grinding or filing it off, or by directly heating the product above the 600 degree maximum temperature threshold. "

ha!! 600 degree maximum temperature threshold thay wish
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  #75  
Old 03-22-2005, 08:34 AM
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found this on the jb weld faq

Q: What color is J-B Weld when it cures? Is it clear?
A: J-B Weld cures to a very dark gray (steel-like) color. We're still working on a clear version that's just as strong as the original.

are thay viewng this thredd?

here is the link there is some cool info
http://jbweld.net/faq.php#faq003

...justin
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