Epoxy, Cruddy Epoxy

O

oldobiwan

Joined
Nov 10, 2006
Messages
3
I follow all the instructions in all the books I have read, but not a single book has said how hard to clamp the handles. It seems that when I have to take one or both off, they just snap off. Am I using to much pressure, is the surface not rough enough, or am I not cleaning it right? HELP!!!!! I am using devcon epoxy 2 ton and let it dry for at least 24 hours.
 
Once you epoxy scales, you shouldn't take them off!
Bill
 
First thing, throw out all the devcon stuff, The very best epoxy I have come up with is from TAP PLASTICS, Four to One Super Hard, This stuff is incredible. Clean the steel with acetone, sand or grind the metal surfaces ( the rougher the better, clean with acetone again, wear clean latex gloves (you do not want to touch the metal with you hands it will contaminate the surface, be sure the sufaces mate properly, do not use clamp pressure to compensate for a poor fit. Use only enough pressure to hold them in place and squeeze out the excess epoxy. If you follow the ebove steps you have to grind or mill them off for removal. But berfore I learne the above proceedure I got used to pinning the scales on & I stil do. I drill the tang with a least 4 holes of the selected pin size. Then I use the tank as a template to drill the scales from the back side, do not drill completly thru. Do this to both scales. For pins I use allan set screws long enough to go thru the tang & into each scale at leat 3/16 in (scale thickness will dictate the length. Noe you have threaded pins that are epoxied into the sacles that go thru the tank, It will not camoe apart PERIOD. Most of the time I want hidden pins that is why I do this way. Because adhesives do not always peforf as desired I ALWAYS USE PINS.

Hope this helps you out Leon Pugh
 
If you use a good quality epoxy properly you will more than likely have to destroy the handles to get them off. I can recommend JB Weld, Brownell's Acraglas, and System Three T88 epoxy as top of the line stuff I have used. Be sure to degrease whatever metal you are trying to glue to with alcohol or acetone. I also like to rough up the scale material slightly for a better bond. Put on a thin layer to both handle and scale but make sure you don't squeeze the parts together so hard that you squeeze all of the epoxy out. Light pressure will do. When you glue slab type handles on I also like to make some shallow random direction gouges in it to hold more epoxy in there after roughing the handle up.

If you follow these steps it will be very hard to get the handles off without serious damage to them. If you have some pins in the handle and epoxy those in also it will make the handle joint even stronger. Stay away from the 5 minute or 30 minute epoxy types.

Alex
 
Clean surfaces as others have mentioned is extremely important. The best epoxy in the world will not stick to steel or wood if it has any kind of oil, dirt etc. Sanding the surfaces down with a coarse grit is the best way to go to both clean and prep prior to gluing. Use the glue at the recomended temperature range. If your shop is cold, put the fire on and warm it up prior to working with epoxies or glue. I use a good two part epoxy from a reputable manufacturer. Lepage's two part epoxy has worked well for me in the past.
 
As for releasing handle scales and such, you guys probably know this, but if you hit it with a heat gun, most epoxies let go around 250 degrees or so (not jb weld, but many do) they turn into a kind of grainy cake type substance which crumbles easily in your hands. As for attaching the scales to a knife, have any of you guys tried golf club shafting epoxy? That stuff is some amazing glue....make sure you get the stuff for steel shaft attachment and not graphite shaft attachment.
 
i use acetone to clean handles before applying devcon 2 ton. You dont waht to use very much pressure. also don't let the handles get hot if you are trying to shape them.
 
Glue sticks via a chemical process, not a mechanical one. Roughening a surface doesn't help if you don't make the surface chemically active in the process. To be chemically active you need to remove more than simple surface contaminants. You have to strip the surface down to fresh metal and fresh wood (or whatever your handle slabs are made of). Right after a surface is cut, machined, or ground atoms are exposed at the surface that used to be part of the interior of the material. They have dangling chemical bonds that want to attach to something. In a matter of hours to minutes those atoms will find oxygen, water vapor, or dirt to bond to. Some will actually sort of readjust and connect to other neighboring atoms in the material. At that point you can only get a suboptimal bond to that surface even if you clean it with a solvent.

When I was working in aerospace the preferred way to prep a surface for epoxy bonding was with a specialized acid etch. For aluminum that was with a mixture of sulfuric acid and sodium dichromate. I was not trying to roughen the surface, I was trying to strip the surface. After etching I would rinse surfaces with a deionized water spray. Wiping the surface with a solvent would actually contaminate it and I would certainly not want to sand it after etching. When you don't have the right etching chemicals or the setup wouldn't allow for using them then sanding can be the right approach. First you clean all oil off the surface using a solvent or detergent. Then you take fresh and clean wet-or-dry paper and sand the surface. You don't want to just scratch up the surface since you are not trying to make some grooves for mechanical attachment. You want to remove all of the existing surface. Typically around 220 grit to 400 grit will do an efficient job. Then wipe off the dust with a clean rag and bond immediately.

With any adhesive you need to leave in enough glue to do the job. You don't want to clamp too hard and expel your glue. You can intentionally mix a small amount of clean sand into your glue which will prevent your bond line from compressing too thin (as long as you don't apply too much clamp pressure). There are glass-filled epoxies that come with microscopic glass beads for this purpose and to keep the resin from running too easily. I typically take care to apply a reasonable amount of epoxy and then press the bond together with a weight. Usually that is a few books.

Be sure to mix your two components very thoroughly and don't do your mixing on your bonding surfaces. I like to mix on graph paper to aid in matching my hardener and resin quantities. After mixing I transfer the epoxy to another piece of paper before I use it. I discard my mixing stick and use another stick for applying the epoxy to my bonding surfaces. I want to preclude getting any undermixed components into my bonding area. I save this applicator stick and the remaining epoxy so that I can see how well the epoxy sets up.

Epoxy often bonds better at slightly elevated temperature. I like to set the material I am bonding in a warm spot. This can be in the sun, by a heater vent or under a desk lamp. If the surface is a little uncomfortable to hold it is hot enough.
 
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