how strong is epoxy?

[cerndog]

hello carvers,
I have made a few laminated wood knives with warren blades and one razor knife a-la rick ferry (it is my new favorite- rick you have another fan). I sandwiched the blades in a recess between the wood and used 90 minute 2part epoxy to set the blades and in some cases glue the two handle halves together. or I used epoxy for the blade and yellow glue for the handle portion.
My question is, if others have done it in a similar way, how has the epoxy held up with use?

thanks,
mike

[cerndog]

where are all the knifemakers?

[Just Carving]

Hi Cerndog.

Sorry I didn't answer, but I've just started using the 2 part epoxy--sets up in 4 hours--a few weeks ago.

Previously, for the last 2 years or so, I have been using Elmer's polyurethane glue--the kind like Gorilla glue where it reacts with water. The polyurethane glue was okay, but from what I've seen so far--a couple of weeks of on and off usage of the tools--the epoxy is better. So for now, that's all I can tell you.

[whitecree]

I use that cheap 5 minute epoxy to set blades into handles. It takes 24 hours before it is fully cured, according to the package.

I've broken handles before the join will break. One blade I have, I've gone through 3 handles for. Each time, it was not the glue that gave way, but a fault in the wood.

They use epoxy resin - very similar to epoxy glue - on wooden aircraft. Scary to think that some small aircraft are held together wth nothing but epoxy and a single bolt in places...

[Thomp]

I have set quite a few blades with gorilla glue, same as your Elmer's polyurethane but has a yellowed to brown color to it,,
the gorilla glue has failed in 2 of the knives but the Elmer's 5 minuet epoxy has held so far...

i think this is attributed to me sanding the warren blades up to where it was exposed so that the socket ed part of the blade had a place where the epoxy could get a grip.

lot of the knives i made so far was a single slit in the handle like with a hacksaw then covering the warren blade end and spreading epoxy into the slit, and then wrapping the joint with Saran wrap to contain the reserve epoxy

later after set time done sanding to smooth and let stand to cure/

my best done handles are ones with copper brass aluminum or stainless steel tubing used as socket Ferrel's forced on to strengthen the joint i feel safer when the blade has a metal retaining mechanism even though it is epoxy ed..

pinning is another method i employ when i can get a drill bit through the blade tang, but most warren blades are too hard for my dull bits .. i use copper wire as a rivet and use 2 pins when i can.

other times i try to match the size of the thickness of the blade with a drillbit and drill a seccussion of ajoining holes to allow the blade to be pushed into when all the material is cross drilled out... then set in epoxi or jbweld.

[squbrigg]

I have experimented with several glues and epoxies, and have concluded that the 5 min epoxy works best for me. Yellow glue doesn't seem to have the strength and seperates, the Gorilla Epoxy foams up and while strong, it just is a mess to fix afterwards.

I have sandwiched two, three and even four layers of various woods to make handles, and have also drilled a single piece for a handle. I have had one finished set handle fail, too much stress not enough wood. I have found that in a sandwich handle, a carved in recess for the blade is essential to a sound blade/handle joint, the smaller the tolerance the better.

I just wish I was better at shapeing and sharpening blades.

Bob

[cerndog]

those are some good ideas. to thomp: I once had success drilling through a tablesaw blade to make a pin hole for a knife handle. I just started in with a dremel with a grinding tip. Just keep digging away keeping the hardened metal cool with water. when I got the hole close to the size i wanted, i cleaned it up with a drill bit i didn't care about in the drill press. WARNING: Clamp that sucker down!! It drilled through, climbed up the bit and i had a near sharp knife blank spinning toward me like a helicoper blade. i was lucky it didn't fillet my face or wrist! Duh!

[Thomp]

I Never used a table saw blade to make a knife , except for once i made a replica Eskimo euelu(sp), out of a heat treated dizzon blade but still found them too soft of steel, to even cut up deer meat for sausage...

but have used the long meaty power hacksaw blades,

i don't build a knife unless the blade or steel passes the scratch test with a brand new quality file. the blade has to be hard, but not brittle enough to break,,
taking a new file And using only a corner edege of it try to remove some of the steel from the intended blade, (You dont have to try to cut it in half, just a nick, ) in time you will learn more by using this method, about hardness..

if you can cut it freely as cutting a 16 penny nail, toss it aside... and don't use it,

but if you find something the file wont scratch such as glass or hardened plainer blade toss it aside as well its brittle,
but if you find a piece of steel that you can just barely get fillings to come off you have a prospect for a knife.


Files are great hard material but when they are put in a bind they shatter, like a regular hand hacksaw blade, or glass.
you don't want that to happen when your bearing down on a power cut.

for a good blade to hold an edge it has to be hard...and a sterret power hacksaw blade is easily found and pretty available at machiene shops or supply house outlets...that for sure,
heck i still think flexcut tools are metal cutting bandsaw blades reworked.. but thats my knundrom,,,

i use a 4 1/2" side grinder mounted on a jig from harbor freight that turns the side grinder into a chop saw, with a weld cutting abrasive disk on it and a water drip, made from a 3 liter bottle like an IV drip and aquarium air bubblier parts, adjusting the valve on the water drip i keep the steel cool, then i cut off billets of the power hacksaw blade for my short bladed knives.
.
then use my dremel with diamond bits to drill into the blade for mounting,keep the bit cooled as well , or the little stones
sometimes after just making a noticeable dimple i take it to the bench drill press put the raw billet in the drill vice and drill it with a brand new high speed steel
it usually takes a new bit for each hole... keeping it under a flood of 30 wt oil.
if the blade survives the drilling i work out the shape and roughly sharpen it.

as far as making glue ups for knife handles I'm currently making some knife handles similar to the flex cut brand, but a little beefier to fit my old mitt.
one in particular I'm making is walnut center with beach outer slabs. it should look like a reverse skunk but i have used Elmer's carpenter's glue to glue the wood and i intend to use 5 minuet epoxy to set the blade as soon as i get it finished.

hope i passed on something usefull you could use...

[Hi_Ho_Sliver]

I have been inletting both halves of the handle, half the thickness of the tang, I usually don't even try to drill, I just serrate the edges of the tang on the grinder before inletting, and for glue have been using elmers polyurethane.... none have come apartCowboy

[Thomp]

It probably wasn't a clear analogy of the gorilla glue to say it failed because of the way i did the blade insertion the tang of the warren blades wasn't serrated as hi ho mentioned nor was the blade sanded on the tang..

the blade tang was pressed into a slot filled with gorilla glue then wrapped with a piece of polypropylene plastic to keep all the glue contained... i find this makes the gorilla or polyurethane glue to expand deeper into the recesses and pores of the wood, not run out and stick the project to the table.

maybe if 2 things were to be redone,
1 and or grind the tang rough
2 open up the slot in the handle to allow more of a space for the glue to actually touch everything.. not getting scraped off as it was pressed through the slot..

Also both blade/handles failed while making a pulling twisting cut on a cowboys neckerchief on the same flute of fabric - wrinkle