epoxy problems

K

knifemaker3

Joined
Dec 26, 1999
Messages
119
Hey guys!

I've been using Devcon 5 minute and 2 ton epoxies for 10 years with good results. But here lately, I've been having handles just fall off before I get the rivets in!!!

Anyone else having this kind of trouble? Any suggestions? And before anyone asks, I follow directions.
tongue.gif


Thanks in advance!

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Craig Blankenship
Blankenship Knives
http://www.blankenship-knives.com
 
I clean both the scales and the blade with acetone before I try to epoxy anything. "If" any oil at all, including from your hands, gets on either there will not be a good bond. "If" you are "over clamping" the scales, this will squeeze out too much epoxy and not leave enough for adhesion. "If" you are getting the epoxy too hot by grinding on the scales, the epoxy will tend to let go. I know, its a lot of "ifs".


One other word of advice (and I am sure that there will be those that disagree with me); I would shy away from the 5-minute variety of epoxies. They are not waterproof.

C Wilkins

C Wilkins
 
Don't use 5-minute epoxy, for many reasons.

Not only clean the surface you are bonding to, create a new surface for bonding. Time, oxidation, mechanical operations, etc. make surfaces hard to bond to. The surface atoms have settled down to bond to each other and don't much want to connect to anything at the surface. Use clean Wet-or-Dry paper to remove the surface layer on the tang and the handle material. This will leave lonely atoms on the surfaces that "miss" the neighboring atoms you have taken away. For several hours this new surface will be dramatically more receptive to bonding.
 
Well, I dont know much about the atomic layer (hes probably talking about the molecules right?) but i do know devon aint that great, any of it. and if your handles are coming off its cause, as mentioned above, youre getting the metal up to the temp where it melts the epoxy, or youre clamping all the epoxy out (dry joint from squeezing it all out) or you have oil somewhere...my recommendation, first change your epoxy...use the stuff K&G sells, its unbelievably strong, or T 88, thats what i use, two, careful about the heat, three, and most important of all...with a small wheel grind a slight crater in the center of the handle where the epoxy is going, if you want you can do it both in the metal and the handle material, it doesnt have to be deep, i use fresh 50 grit, a 3 inch wheel, and try to take the "rough up out to about 3/16" from the edge of the knife handle..when i am using a wood that has a tendancy to not bond, like cocobolo or lignum or teak, i do the same to the handle material....you dont have to grind it deep, just put the 50 grit scratches in........try it....it works...
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http://www.mayoknives.com


 
Guys,
Thanks for the responses. I've always used the same steps for glueing with this stuff.
1. roughen both tang and scales with 36 grit sandpaper
2. wipe everything with acetone
3. mix for 1 minute before application
4. clamp and let dry overnight.
5. drill out holes.
6. repeat for other scale
7. screw in Loveless rivets.

I've always had good luck this way and have never had a scale just drop off!!!!

Oh well....

Tom, I'll try the other epoxy!!!

Thanks again guys!

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Craig Blankenship
Blankenship Knives
http://www.blankenship-knives.com
 
One other thing to ponder.......
Has the epoxy frozen or gotten really cold or just old? Either of these can cause bond failure.
 
I assume the tang and the scales are FLAT, 36 grit gives a little bite...but if you try my method of grinding a crater in the handle, your problem will go away...i started doing it via the way bob loveless teaches how to taper tangs in his book, and then started getting a nice little hollow in the middle all the way to the edge...i wont twist your arm...but it really works good.

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http://www.mayoknives.com


 
I just use a dremel with a drum or a cut off wheel to grind some random grooves in the tang and the scale. Don't stray over the edge of the tang and mark the outline of the tang on the scale and stay 1/8 inside the lines.

For epoxy, I use acraglass rifle bedding compound. You can get it from most good gunshops or order from brownells. It's a 4to1 ratio mix, so go to the pharmacy and get a 10cc and a 3 cc non luer lock syringe to measure 2cc's of resin and 1/2 cc of hardener. Just the right ammount for a normal knife.

James

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Those who are willing to trade freedom for security deserve neither, and in the end, seldom retain them!
 
I taper tangs the same way as you do Tom, but usually don't pay much attention to whether there is a crater left or not. I've just never had an epoxy failure with anything I've used. The one or two times I've had to remove a handle slab, by sawing most of it off then scraping the rest, it was a bear to remove. And once that was with 5 minute epoxy and without any support from the pins.

It might be a long shot, but Craig what are you mixing your epoxy on? It might be you're picking up some contamination from that. Many things are coated with wax or resins and could interfere with the epoxy chemistry. I use Brownells epoxy mixing pads.

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Jerry Hossom
www.hossom.com
 
I gave away my Devcon 2-ton epoxy. (Bought 5 pacs 2 months ago) Since then I've purchased 18 different epoxies and putty like adhesives. After weeks of tryouts (metal to metal, metal to wood & stag and wood to wood), using the suggestions posted above and previously such as cotton or rubber gloves, acetone, hollow spots, 75º-95º curing temps, recent pre-sanding...my definite top five are K & G Epoxy, T-88 with a 4 day cure time, Brownells Accra-glas & Micro-bed and J-B Weld. BTW, K & G has epoxy colorants which are very useful.

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Joe
 
Hey guys,
Thanks for all the responses.

I'll try grooving the next one and using some of the different adhesives mentioned.

And now that it has been mentioned, I have went from mixing on pieces of cardboard to using whatever is available at the time. I may be picking up something and just hadn't thought about it.

Thanks and have a good one!
smile.gif


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Craig Blankenship
Blankenship Knives
http://www.blankenship-knives.com
 
After trying different kind of epoxies, I have settled on Conap. It can be purchased from Sheffield. It is easy to mix, easy to use, and does a great job.
 
you could have gotten some bad epoxy you know sometimes it not what your doing wrong it's what somebody else did wrong.they make large amounts so there may be a lot to go around.
 
Hey Craig, I use plastic lids from old butter tubs and such for mixing epoxy. Of course you have to wash them first, but the lips on the edges help keep the epoxy contained when you're mixing bigger amounts, and the price is right.

Jake
 
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