Hammers, pins and peening...

[AVigil]

Especially seeing as I have to peen the pins while the epoxy is squeezing out and setting...

You do not have to do it then. What a nightmare...

Once the epoxy sets then cut your pins and file them close and peen them.

 

[Horsewright]

Aaron it looked like no epoxy had been used, just the peened pins. I think just the weather had got to it from the two months it was lost. But we're pretty dry, desert country so it wasn't like sitting in a swamp or anything. I've seen several of this guys knives and they ain't much. I agree with Bill, proper peened pins have been working for centuries. I have a John Newton Sheffield bowie. It has jigged bone scales one of which has cracked off. Other side is solid as a rock. My wife's grandfather carried it throughout WW2 and it was old before then. I've got it in my hand now and I could tell ya it would take more than one tap to get that other side off.

 

[Josh Mason]

This is going to sound so stupid..... but how about just epoxying the handle and inserting the pins, grinding everything flush after curing and not peening them at all? I'd make a couple test knives and see how the handle held up versus the peened pins.

Someone chime in and tell me if I'm out of line here...lol

 

[FTO_dude]

I agree 100% Josh.

I think the negatives far outweigh the positives here. and more to the point, a properly prepped joint is more than strong enough for any knife handle.

 

[Andy Lewis]

This is going to sound so stupid..... but how about just epoxying the handle and inserting the pins, grinding everything flush after curing and not peening them at all? I'd make a couple test knives and see how the handle held up versus the peened pins.

Someone chime in and tell me if I'm out of line here...lol

Not at all Josh. I imagine most knives rise or fall over other issues besides whether handle pins are peened or not. Their main function is to reduce mechanical shearing as I see it. Prepped properly and epoxied with the good stuff, I imagine straight pins can still be part of a seriously overbuilt knife.

I use very little epoxy here because the scales are already cured out on tang and bore tolerances leave minimal gaps. Quick peening is just extra security over the longest haul (pretending that matters here) but mostly it reduces the annoying dark halos on some of the lighter handle materials.

Main thing here is to consider what and why you do this (or not), and evolve your practice till it becomes routine and meets your personal goals. And as you said testing is always a great idea - it's fun and you learn something about YOUR stuff.

 

[aarongough]

You do not have to do it then. What a nightmare...

Once the epoxy sets then cut your pins and file them close and peen them.

I hate to sounds silly, but I hadn't actually thought much about doing it that way. I just assumed the epoxy would be too hard to get out of the chamfer/counter-bore and would leave gaps. I'll have to try it sometime!

Aaron it looked like no epoxy had been used, just the peened pins. I think just the weather had got to it from the two months it was lost. But we're pretty dry, desert country so it wasn't like sitting in a swamp or anything. I've seen several of this guys knives and they ain't much. I agree with Bill, proper peened pins have been working for centuries. I have a John Newton Sheffield bowie. It has jigged bone scales one of which has cracked off. Other side is solid as a rock. My wife's grandfather carried it throughout WW2 and it was old before then. I've got it in my hand now and I could tell ya it would take more than one tap to get that other side off.

Interesting that dry weather was enough to pull the scales off, seems like a shame. I might have to send one of my knives to you and have you leave it outside for a few months to see how it goes!

This is going to sound so stupid..... but how about just epoxying the handle and inserting the pins, grinding everything flush after curing and not peening them at all? I'd make a couple test knives and see how the handle held up versus the peened pins.

Someone chime in and tell me if I'm out of line here...lol

Not stupid at all Josh! For most knives that will be totally fine. Kitchen knives and other light-duty knives especially that will be sufficient... Provided that the glue joint is prepared by sand-blasting. I've tested glued and pinned joints (no peening) both with and without sand-blasting. The sand-blasted glue surfaces provide a much larger surface area for bonding and make a huge difference.

The peened pins (or other mechanical fastener) in combination with a good glue joint really seals the deal, and with that setup you can break a blade by prying and the handle will still be intact. I tend to over-build my knives wherever it doesn't get in the way. I don't make my knives for prying, but I like to know that the handle is going to withstand any abuse the blade can take and more...

I agree 100% Josh.

I think the negatives far outweigh the positives here. and more to the point, a properly prepped joint is more than strong enough for any knife handle.

For knives that will be used as knives and not abused I tend to largely agree. knife that might see abuse needs a little more though. I've tested several knives to destruction using different pin/glue combinations... Scales that are epoxied to the tang without sand-blasting, and pinned without peening can be popped off the tang pretty easily by levering on the blade a bit. In my testing I was able to do it without even breaking or bending the blade.

Add sand-blasted glue surfaces and/or peened pins and you start getting something special!

Not at all Josh. I imagine most knives rise or fall over other issues besides whether handle pins are peened or not. Their main function is to reduce mechanical shearing as I see it. Prepped properly and epoxied with the good stuff, I imagine straight pins can still be part of a seriously overbuilt knife.

I use very little epoxy here because the scales are already cured out on tang and bore tolerances leave minimal gaps. Quick peening is just extra security over the longest haul (pretending that matters here) but mostly it reduces the annoying dark halos on some of the lighter handle materials.

Main thing here is to consider what and why you do this (or not), and evolve your practice till it becomes routine and meets your personal goals. And as you said testing is always a great idea - it's fun and you learn something about YOUR stuff.

Testing really is the name of the game as far as I'm concerned. I think everyone has their own thresholds for how over-engineered they like to make their knives. Mine are kinda high, probably because I was really mean to a lot of nice knives when I was a kid

 

[Bill DeShivs]

Epoxied handles probably will hold. Handles with properly peened pins will definitely hold.

 

[aarongough]

It was a bit of an interesting evening. I did the rounds of my local hardware stores and managed to get a full set of ball-peen hammers. 2oz, 4oz and 8oz:

I then took a scrap of G10 handle material, along with some of the new 304SS pin stock that I bought and tried each of the hammers out:

The handle material is Black G10 laminated to a thin spacer of ruby red G10. The red is translucent and you can see that it's already showing up the crazing on the 8oz test pin quite strongly.

I then ground the pins back to have a look what I'd ended up with:

As you can see the 4oz and 2oz hammers made it much easier to avoid crazing on the black G10, but clearly the red is very sensitive to this issue. To date I have never used the red as anything except a liner so that's not a huge problem.

I then took the test piece to the disk grinder so we could have a look inside the block to see how the pins deformed:

If you look closely you can see that the pin peened by the 8oz hammer has actually expanded along it's entire length, you can see crazing all the way through in the cross-section. Not ideal. It's also obvious that my counter-bore technique is definitely off the mark. Those pin ends want to be conical and they're crushing material out of the way to get there...

After trying all that I started seriously looking at the mini Corby rivets that I had in my drawer. I started messing with them and some scrap handles a bit more and I'm feeling more comfortable with them. I'm going to do a strength test on them tomorrow using some scrap handle scales, and a scrap O1 blade and see how that goes. If they're strong enough then I think the extra expense may pay for itself with much less stressful glue-ups, and also much reduced chance of scrapping a knife due to aesthetic handle issues at the last moment.

Thanks to everyone that suggested the rivets, it's reassuring to know that so many people like them!

I'll post a thread tomorrow about testing the Corby rivets...

 

[AVigil]

If you want to remove wet epoxy use white vinegar. It will wipe off with ease. Great at getting it off the hands as well

 

[james terrio]

I think a lot of people make handle-building in general much more complicated than it really needs to be, regardless of which fasteners they use. It is just not that difficult to build a solid, strong, well-sealed handle that will more than likely outlive the blade itself - unless someone takes a saw or grinder to it. I assure you, any cabinet maker worth his salt would laugh at how much we fret over such simple joinery

Cool experiment. There's nothing "wrong" with peened pins when they're done right.

But I'm tellin' ya, once you get used to using Corby bolts (which takes about a day) you'll seldom bother with anything else on a fixed blade. They're nearly idiot-proof.

 

[Karburized]

Seriously, use a tack hammer. Much greater control than the smallest ball peen shown. While your typical tack hammer is 5 oz, you just get much better feel for the actual striking force.

 

[aarongough]

I think a lot of people make handle-building in general much more complicated than it really needs to be, regardless of which fasteners they use. It is just not that difficult to build a solid, strong, well-sealed handle that will more than likely outlive the blade itself - unless someone takes a saw or grinder to it. I assure you, any cabinet maker worth his salt would laugh at how much we fret over such simple joinery

Cool experiment. There's nothing "wrong" with peened pins when they're done right.

But I'm tellin' ya, once you get used to using Corby bolts (which takes about a day) you'll seldom bother with anything else on a fixed blade. They're nearly idiot-proof.

I'm definitely leaning that way James! I like idiot-proof as it means I can be productive even on a bad day

If the little Corby bolts pass my testing tomorrow then I'll likely move to using them combined with epoxy and that will be that!

 

[aarongough]

Epoxied handles probably will hold. Handles with properly peened pins will definitely hold.

My thoughts exactly mate!

 

[elementfe]

We do a lot of rivets, punching, drifted holes, tapered holes in blacksmithing work, and I've moved the techniques that work over to knife work.
First, dome the rivet head when it's been cut to length- that keeps the force of the blow centered, and minimizes collapse and distortion. It will flatten and spread, after it has thickened somewhat....this might be a problem if you're just HEADING a rivet, rather than upsetting and setting it. Spinning is real good for that.
I taper ream the holes and get great results- my production knives have tapered holes with rivets sanded flat. I actually upset (squash to shorten) 1/8 rivets with the flat of my itty bitty ball peen hammer, but the head of that is domed and polished, not flat.
I'm not convinced that the softest material is going to always be the best- the hazard is that the shaft of the rivet distorts before the head gets nicely spread.

Edit: I didn't see your test photos- very nice!
If you're not taper reaming, then you wouldn't want to aim for an upset (thickened) rivet. I'd agree with the other guys that a chamfered hole needs a light hammer and a bazillion light taps, since that will keep the distortion very shallow.

Only other thing- I consider kitchen knifing to be fairly tough duty, due to the constant wet, dry, hot, cold, and soap. Obviously you're not prying apart buffalo knee joints in the kitchen, but a crowbar is probably betta for that anyway

PS- The tech guys at West Systems told me that with G-flex, at least, wet sanding doubles the bond strength. As in, a bit of epoxy on some abrasive (I use old 60 ceramic, since it doesn't seem to shed crud) and wet sand just before you spread a real coat on the steel.
Sandblasting is good, but the problem with adhesion is actually the oxide layer, which reappears right after you blast. That's why if you wet sand, it doesn't reform. So they explained it...YMMV

For kitchen knives, you can get away with glued brass or SS pins....for a while. A positive mechanical bond lasts longer, though all you have to do is sharpen knives for the public for a season to see that nothing actually lasts forever, short of a one piece blade/bolster/handle all steel knife. Some people like em.

 

[aarongough]

If you want to remove wet epoxy use white vinegar. It will wipe off with ease. Great at getting it off the hands as well

Vinegar does indeed work well! I tend to use ethanol instead though as it evaporates more quickly and lets me see any spots I missed...

I am devout about wearing gloves and avoiding all skin contact when using epoxy, I've heard some nasty horror stories about what happens when you become sensitized to the stuff... It's worth noting too that if you get epoxy on your skin you should never using anything solvent based to wipe it off, as the solvent will help transport a bunch of the nasty chemicals right through your skin. That's what I've heard at least...

 

[aarongough]

We do a lot of rivets, punching, drifted holes, tapered holes in blacksmithing work, and I've moved the techniques that work over to knife work.
First, dome the rivet head when it's been cut to length- that keeps the force of the blow centered, and minimizes collapse and distortion. It will flatten and spread, after it has thickened somewhat....this might be a problem if you're just HEADING a rivet, rather than upsetting and setting it. Spinning is real good for that.
I taper ream the holes and get great results- my production knives have tapered holes with rivets sanded flat. I actually upset (squash to shorten) 1/8 rivets with the flat of my itty bitty ball peen hammer, but the head of that is domed and polished, not flat.
I'm not convinced that the softest material is going to always be the best- the hazard is that the shaft of the rivet distorts before the head gets nicely spread.

Interesting points! I had wondered about using a tapered ream, good to know that it works!

What you described regarding the 'too soft' material is something I experience a bit today with the 304SS actually. I noticed that the pins were well and truly bound into the pin holes well before the heads had expanded noticeably. Not sure if 303 or 416 behaved the same though to be honest...

 

[Josh Mason]

But I'm tellin' ya, once you get used to using Corby bolts (which takes about a day) you'll seldom bother with anything else on a fixed blade. They're nearly idiot-proof.

Great! Because I'm an idiot!

 

[james terrio]

Only other thing- I consider kitchen knifing to be fairly tough duty, due to the constant wet, dry, hot, cold, and soap.

I agree. Also, it seems that the typical home cook (and apparently pro chefs, if we believe what we see on TV) cares/knows much less about using and taking care of a nice knife than the typical outdoorsy person.

PS- The tech guys at West Systems told me that with G-flex, at least, wet sanding doubles the bond strength. As in, a bit of epoxy on some abrasive (I use old 60 ceramic, since it doesn't seem to shed crud) and wet sand just before you spread a real coat on the steel.
Sandblasting is good, but the problem with adhesion is actually the oxide layer, which reappears right after you blast. That's why if you wet sand, it doesn't reform. So they explained it...YMMV

That's fascinating and makes sense, thank you for sharing that :thumbup:

Great! Because I'm an idiot!

Me too!

 

[Shaw Blades]

Good thread! Great pictures too Aaron.

 

[aarongough]

Good thread! Great pictures too Aaron.

I was pleased with how the pictures came out eh! I got a new smartphone with the intent of using it to take lots of 'on the fly' pics around the workshop and it seems to be up to the task which is nice!