3-7-05 My friend Steve Sando http://knives.mylamb.com/index.htm (great looking knives Steve) started mumbling about doing a glue test awhile ago and I thought it was a dandy idea. I said I would do one also. Well he did his and now I have to step up and do mine. That will teach me to speak up. Anyway, it’s a good idea so here is the start of it. I have about a dozen different glues and epoxies, a sheet of metal and some WSSI stabilized wood. I’ll start the glue up tonight and get at least part way and finish the glue up this week and let them sit a bit to cure.
3-7-05 Here is the start. Using approximately 1” squares of wood, each will be glued and clamped to the metal per the instructions. hahahah I crack myself up. Instructions? Instructions? We don’t need no damn instructions. We glued the crap up and let it set
2-7-05 Here is some wacked out glue. It is a two part epoxy that is billed as waterproof marine expoxy. It says it will even cure under water. I didn’t realize the stuff was blue until I cut open the tube getting ready to mix it up. The blue color basically takes it out of the hunt for being a suitable knife epoxy but I’ll test it anyway. It also says it is flexible and Steves tests show that is a plus. We’ll see. Besides being an awful color of blue, it stinks to high hell. More pictures later as the great glue off continues.
3-12-05 The adhesives have all cured for a couple days. Time to tap test. I’ll use three progressively larger hammers and tap the edges of the wood blocks to simulate dropping a knife onto a hard surface giving a sudden, sharp shearing force. 3 to 4 taps each piece.
3-12-05 To the right, the middle tap and below the big tap most commonly known as the BFH. Every one made it through the little tap. Our first failure came from the middle tap, the contact cement just popped right off. I believe the little tap loosened it, the middle tap failed it. All passed the big tap test. I didn’t smash like a mad man but if you look at the picture below you can see where the wood was damaged on the edge by the big guy. I gave everyone an extra bump or two with the BFH and they all still held on - for the moment.
3-12-05 I stuck the test material into the freezer for a couple of hours and then took it to my shop to repeat the tests while every thing was still sub zero. I went right to the BFH and gave every one several good knocks. The Devcon 2 failed immediately. The surface of the epoxy looked glazed and it appears the metal was smooth. Some of the epoxy sheared off and stayed on in the micro grooves in the metal, but not all that much. I think a combination of things failed this epoxy, cold temp, minimal surface prep and it doesn’t like sudden-shock shearing force. Every one else did a great job holding up
Here is the list of adhesives we are going to beat until they fail.
2 part epoxies
T-88 2 part epoxy
Clubmaker Shafting Epoxy from Golfsmith
Devcon 2 ton
Devcon 5 minute
Super Glue brand Metal Epoxy
Anchor Tite brand Marine
Loctite 416 superbonder 41650
Handibond Rubber Toughened Super Glue
Elmers Ultimate glue (looks identical to Elmers Probond)
Tanners Bond contact cement
3M Hi-strength 90 spray adhesive
my wifes hot glue gun
Some others I just found in some local stores that I will be trying out
loctite contact cement
Super Epoxy by PC Products
PC-7 epoxy paste by pc products
All Purpose Welder
Liquid Nails 2 part epoxy Perfect Glue 3
Elmers Craft Bond Ultra Stix All
3-12-05 Chuck Bybee http://www.alphaknifesupply.com/ kicked in some testing materials and a couple of test adhesives. Here I’ve taken some of the wood and cut it into blocks and then I’ve sand blasted half of the metal strips and will rough surface grind the other half to see if one preparation method provides for a better purchase than the other.
My sandblast cabinet. I cheap one from Harbor Freight but good enough. I used 70 grit AO to roughen up the surface on the test coupons.
3-12-05 Here is the start of the glue for round two of testing. Each block is glued up by the same glue on either end of the metal. The difference is one end was sand blasted, the other just roughed up from a quick grind from a fresh 36 grit belt. It’s going to take a week or so to get through all the glue up for round two and to allow a good cure. Some of these epoxies don’t reach full strength for 3 or 4 days.
3-16-05 To the left see some test coupons on top of 25lb bags of lead shot. Three sets of were glued up using PC-7 epoxy (which is now verified as amazing stuff) to test what affect surface preparation had on how effective epoxy held. One set was sand blasted, one set was roughed up with a fresh 36 grit belt, another set had no preparation done at all. Each of the 2 pieces was glued at a ninety degree angle and allowed to cure for a couple days. They were then placed in a vise and a load applied until they failed.
3-16-05 To the right you can see a load being applied to the test pieces. Here you can see a 50lb load held by a simply lap joint of approximately 1” square of PC-7 epoxy. I was stunned at how much they held. Each test piece held 75lbs! They all failed when I added another 25lbs so I never could measure accurately which surface held more but we can examine the failed joints and come to some conclusions. Note the metal is actually bending from the leverage and weight.
3-16-05 The joint to the left is 36 grit, the middle sand blasted surfaces and to the right no surface prep at all. Starting from right note one piece ended up with most of the epoxy and the other piece had maybe 50% of the surface with epoxy residue. In all three cases, the epoxy failed, not the material, but in the test pair on the right, the adhesion partially failed by not sticking well to the metal. The left pair shows fairly even epoxy failure with 10% or so adhesion failure. The center test shows very even expoxy failure with no adhesion failure visible. The residue coverage was very even on both pieces. The conclusion we can draw is that sand blasting a surface is clearly the best method of surface preparation followed closely by a good, even ‘scratched up’ surface from a new, sharp 36 grit belt. I’ve been using a 36 grit belt but going forward I will be using the sand blaster to surface prep any where I can for better performance.
Mickley Custom Knives