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Question: how do you glue / epoxy knife scales on ? Mine fell off

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Forum topic by coloradoclimber posted 1574 days ago 11092 views 1 time favorited 42 replies Add to Favorites Watch
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coloradoclimber

548 posts in 2570 days


1574 days ago

I bought some fixed blade knife kits from Woodcraft to make for Christmas. The “kit” is really just the blade, I have to add the scales and rivets.

I cut the wood for the scales, sanded the inside, sanded the blade tang, cleaned both the scale and the tang with acetone, mixed some two part epoxy, spread a thin uniform coat, then clamped for 24 hours.

I got the scales thinned to the thickness I wanted and was starting to shape them when the first scale popped off. I checked the other side and sure enough I could see the other scale was coming loose too, a quick poke with a pocket knife under the scale and it popped off too. I checked the others and I could see that at least 3 more were starting to pull loose. I tested them with a pocket knife and they popped off with a little prying. They probably would have held in place for a while but likely would have come off eventually.

So, now what? I’ve already shaped the scales and I would like to use them. I can epoxy them back on but I’m not sure what went wrong the first time. I made 4 knives, the first has wenge scales and those seem to be staying on. Two have cocobolo and 3 of those 4 scales are off. The last was chakte viga, that’s the one that popped both scales off first.

I thought maybe it was the wood, that the epoxy was not sticking to the wood because of some oils or something but when the scales popped off all of the epoxy was attached to the scale and almost none on the tang.

Next I’m thinking maybe it is because of moisture content in the wood. I cut the cocobolo and chakte scales from wax covered turning blocks. The wenge I had laying around the shop for a year or so. I did not let the scales sit very long before gluing them. Maybe a couple days Definitely the cocoblolo and chakte scales seem to have a higher moisture content than the wenge. At least they rasp much cleaner without much tearout. I don’t know if that is a property of the wood or moisture.

I’ve already sent a PM to Mark DeCou, it looks like he’s gone down this path more than once.

So what else should I do? How do you glue on knife scales and any suggestion on whether it could be the wood or moisture?

Thanks


42 replies so far

View dkg's profile

dkg

30 posts in 1587 days


#1 posted 1574 days ago

I do not think that moisture or or the wood is a problem. It might be the epoxy. I have used West epoxy for quite some time. When joing wood, I use the 207 part B because it is compatable with different finishes. I also use a powder adhesive mixed in with the mixed part A and part B. I mix the adhesive until a get a cool wihip consistency. You have about 20 minutes to work with the stuff.

View TopamaxSurvivor's profile

TopamaxSurvivor

14402 posts in 2178 days


#2 posted 1574 days ago

Let us know what you find out. I haven’t done this yet, but am planning to give it a try. thx.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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coloradoclimber

548 posts in 2570 days


#3 posted 1574 days ago

Thanks for the replies. I guess I’m gonna give a different epoxy a try. I used a 2 part slow set from Walmart, I guess that should have been my first clue :(

I did try roughing up both the scale and the tang. I rubbed both on 100 grit sand paper on a flat surface. Mostly to flatten them, remove any burrs, and rough them up a little.

I did wipe both the tang and the scale with acetone before applying the the epoxy, maybe 15 minutes or so before applying the epoxy.

I’ll see if I can hit Rockler tomorrow and pick up some West Systems. If I cant find any I’ll look for the Raka.

I’ll post back after I get them re-epoxied and give them a chance to work or fail.

View Thos. Angle's profile

Thos. Angle

4433 posts in 2464 days


#4 posted 1574 days ago

I did the 2 knives in my projects with two part epoxy that comes in the syringe type tubes. I don’t think I clamped it very long but I did make sure it was in the pin holes as well as on the steel and wood. I don’t think I sanded the back of the scales any at all. I carry the folder in my pants and have carried the belt knife as well. I think it must be the glue.

-- Thos. Angle, Jordan Valley, Oregon

View papadan's profile

papadan

1103 posts in 1870 days


#5 posted 1574 days ago

My guess would be the epoxy you used. I have used the slow setting and 5 minute types to put golf club heads on, always a steel shaft and heads of wood and metal. Never had one come loose. Don’t know the brands off hand, usually buy it at the borgs. You stated that most of the epoxy stuck to the wood and not the metal, so that rules out problems like oils in the woods.

-- Carpenter assembles with hands, Designer builds with brains, Artist creates with heart!

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coloradoclimber

548 posts in 2570 days


#6 posted 1574 days ago

Hmmmm, Dave you might be onto something.

I thought maybe I might have clamped them too hard, as in “I squeezed the hell out of it”.

I had three jorgensen bar clamps per knife handle and I had them cranked down pretty much as hard as I could screw them down, seriously cranked. I figured the tang was flat, the scale was flat, I didn’t want a big seam of epoxy showing so squeeze it till the seam pretty much disappeared. Maybe too much :). I’ll get some better epoxy and maybe go a little bit gentler on it on the re-glue. thanks for the ideas

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coloradoclimber

548 posts in 2570 days


#7 posted 1574 days ago

Well that makes sense too. I give that a try, maybe rout / dremel some grooves in the scale so I can keep some registration surfaces but still add in some volume for the epoxy.

That’s why this is such a great site. Lots of good ideas and good people quick to share.

View interpim's profile

interpim

1123 posts in 1960 days


#8 posted 1574 days ago

I have had real oily woods not take epoxy before…

I was using a decent quality epoxy too. I noticed that when the epoxy heated as it cured it pulled the oil to the surface that was being glued and ended up pushing the epoxy away from that surface.

-- San Diego, CA

View TopamaxSurvivor's profile

TopamaxSurvivor

14402 posts in 2178 days


#9 posted 1574 days ago

Do you know what brand the Walmart epoxy is?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View coloradoclimber's profile

coloradoclimber

548 posts in 2570 days


#10 posted 1574 days ago

The Walmart epoxy comes in two side by side syringes and has “2 Ton Clear Weld Epoxy” written on it, made by ITW Performance Polymers, Riviera Beach, FL.

Another thing I noticed. The epoxy did not stick to the tang at all. Even where there was squeeze out in front of the scale on the the blade. I picked at the squeeze out with the tip of my pocket knife and it flaked right off the steel.

So I’m not sure what is going on with the epoxy bond, or lack of bond, to the tang. I’m going to try to rough up the tang a little extra, make sure I clean it well with acetone, and try some “better” epoxy.

View Moron's profile

Moron

4666 posts in 2395 days


#11 posted 1574 days ago

do u hav a picture?

-- "Good artists borrow, great artists steal”…..Picasso

View John Gray's profile

John Gray

2366 posts in 2387 days


#12 posted 1574 days ago

Picture? Did you pin it too or just use epoxy? What kind of wood did you use?

-- Only the Shadow knows....................

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coloradoclimber

548 posts in 2570 days


#13 posted 1574 days ago

The handles are drilled for pins and a lanyard, but I did not put the pins in yet. I wanted to shape the handles with a rasp first, then glue the pins in, then hit it with a final pass over the spindle sander.

The woods are Wenge, Cocobolo, and Chakte Viga. The wenge seems to be holding strong, the chakte popped right off, and I had to pry a little bit to get the cocobolo off, but it was already starting to pull away from the steel.

Here are some pictures of the scales after coming loose. The first two are of the Chakte, they pulled away perfectly clean, not a bit of epoxy stuck to the tang. The cocobolo left some epoxy behind but a good portion was unstuck. The last picture is of the pins and lanyard tube to be installed after I finish getting the handles rough shaped.

You can see the epoxy squeeze out at the top of the handle where it just came right off of the steel. I did wipe down the steel with acetone before putting on the epoxy.







View TopamaxSurvivor's profile

TopamaxSurvivor

14402 posts in 2178 days


#14 posted 1574 days ago

I have never had epoxy fail to stick to metal. Never heard of it before, but I think I’ll avoid “2Ton epoxy” :-))

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Ger21's profile

Ger21

600 posts in 1633 days


#15 posted 1573 days ago

You must have still had a film of some sort on the steel for it not to stick. One other thing you can do, with the thinner epoxies mentioned, is to wet sand it into the steel with 60 or 80 grit sandpaper. You can do this to the wood as well. West System recommends it for a better bond.

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html

showing 1 through 15 of 42 replies

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