Hammers, pins and peening...

aarongough

aarongough

Joined
Mar 12, 2013
Messages
1,167
Hey guys!
I attach the scales onto my fixed blade knives using a combination of epoxy and peened 1/8" pins. The handle material that I normally use is G10, and I've been having some issues with crazing (white marks) around the pin holes.

I drill the main holes through the tang and scales 1/8" in diamater, then counter-bore the holes in the scales 5/32" diameter about 1/16" deep. The pins are then peened into the counter-bores. I counter-bore as opposed to counter-sinking because I want the pins to all end up the same size...

I have a couple of questions:

1) Which pin material is the most ductile and is least likely to damage the handle material? I've tried 303SS and 416SS, I'm considering trying 304SS as well as I understand it's more ductile... I would prefer a corrosion resistant material which is why I've been trying the stainless steels.

2) Would switching to a smaller hammer reduce the chance of crazing? I will admit that right now I don't have a ball-peen hammer and I've been (gently) using a regular claw hammer instead which I believe is 16oz.

Any advice you guys could give would be appreciated!
-Aaron
 
I haven't gotten around to peening pins yet but I wonder about it from time to time. I wonder if using a nail set of appropriate size will work to peen the pin ends?
 
i4Marc said:
I haven't gotten around to peening pins yet but I wonder about it from time to time. I wonder if using a nail set of appropriate size will work to peen the pin ends?
Click to expand...

As far as I can tell the crazing in the handle material is not from the hammer blows, but from the metal of the pin expanding outward with too much force and crushing the surrounding material... I've managed to do a few without any crazing, but it's been inconsistent. I'd like to iron out the process as it definitely doesn't look right with the crazing.
 
Have you considered trying Corby bolts?

They're a tad expensive, but with a matching counterbore, they're simple to install and fit perfectly every time without the fuss of peening and risking damaging handle material. Plus they add some extra mechanical security.

You can get them in a variety of materials, and they come in 1/8" with a 5/32" head, so they'll fit the holes you're currently making for your pins. I've switched to them almost exclusively for full tang knives.
 
Countersinking or counterboring, you can't expect the softer handle material to contain the expanding pin head.
My peening hammer is a 2 ounce cutler's hammer. Peening pins with a claw hammer is like driving a dump truck to work.
Try brass or nickel silver pin stock, and a small hammer- using wrist action only.
 
weebus said:
Have you considered trying Corby bolts?

They're a tad expensive, but with a matching counterbore, they're simple to install and fit perfectly every time without the fuss of peening and risking damaging handle material. Plus they add some extra mechanical security.

You can get them in a variety of materials, and they come in 1/8" with a 5/32" head, so they'll fit the holes you're currently making for your pins. I've switched to them almost exclusively for full tang knives.
Click to expand...

I would love to be able to use Corby bolts actually! I tried using the 5/32" mini corbys from Jantz, the overall length of the fasteners didn't quite work for my handles though unfortunately. I also sheared the head off one with very little force and that kind of scared me off them.

If there are other sources for Corbys with 5/32" head diameter and more length options I would love to know!

I honestly quite like the peened pins. If I can nail down the process I would be a happy guy!
 
Bill DeShivs said:
Countersinking or counterboring, you can't expect the softer handle material to contain the expanding pin head.
My peening hammer is a 2 ounce cutler's hammer. Peening pins with a claw hammer is like driving a dump truck to work.
Try brass or nickel silver pin stock, and a small hammer- using wrist action only.
Click to expand...

Totally agree on the hammer. It hadn't occurred to me that it might be part of the problem until today when the lightbulb went on, not sure why that took so long!

I understand that the handle materials won't be able to contain the pin if I'm hitting it hard. Part of my thought process today was that maybe if I'm using a smaller hammer and lighter blows, therefore injecting less energy into the expansion of the pin, then it won't have enough energy to crush the handle material... Or at least won't do it as easily.

Am I totally off base with that thinking?
 
Have you thought on Loveless bolts? Not quite as finished as a Corby but strong as heck. Used em on quite a few knives that went to the Sandbox. All handles stayed put. I recently re handled a friends knife for her, one I did not make. Peened pins and elk scales. The knife had been lost in a pasture for a couple of months and the scales were pulling away. One light smack with a hammer and they both fell off. Knowing the type of knives you like to make Aaron, think hard on the Corbys or Loveless bolts.
 
If the pin head gets bigger than the hole it's in, something has to give.
Tha advantage to using a small hammer is that you can move small amounts of metal where you want it to go, and do it precisely.
Bolts are very secure, but properly peened pins are secure, too. Scales have been pinned on knives for hundreds of years.
 
+1 for brass. Have you ever tried copper? Obviously very soft, and looks very nice on knife scales.
 
I just bought some annealed 304 stainless rod which I believe should be more malleable than the stuff I've tried in the past. I'm also going to go and get a much smaller ball-peen hammer today (2-4oz).

I'll report back with results after I try it out later tonight.
 
Hey Aaron. Sounds like you you pretty much got it but still I have a couple of thoughts on pins and pinning:

Loose the claw hammer as mentioned. Buy a quality machinists ballpeen in the 2 to 4oz range - take it home and dress/polish both ends to 600x or better and dont use it for anything else but pinning. Both your control and finish will likely improve shortly.

Lock your elbow at side and use your wrist. Plan many light fast taps/strikes for each pin. And forget the ball end of the hammer when starting out. Your tiny pin diameter is the work's bottleneck; the flat polished face of the hammer gives much better control for proud pins (to be ground flush later) at roughly the same work per tap.

As important as the hammer, so is the anvil it sits on. Whatever your final choice, use the same one the same way each time. A hard face, backed up by mass, always wins on mechanical efficiency (why I use my main anvil FWIW). I have a decent bench block that gives good results with some practice but MY anvil just feels ideal to me for this ritual.

I would question the need (and time) taken to accurately counterbore pin holes in an effort to unify finished pin diameters. As Bill said, I don't expect G10 (or any common scale material) is anywhere near hard/strong enough to contain a hammer-peened pin head without distortion and/or radial crazing. The idea of the shouldered counterbore containing a tapered pin is odd to me personally but I have not tried it.

Burt Foster gave me some good general advice on pinning natural scale materials several years ago and I have cracked or fouled very few since. Basically I drill tang's holes slightly oversize, HT, epoxy first scale, drill first scale undersize using tang as template, epoxy second scale, back drill both scales at nominal. Then I turn down pin material a few thou below nominal bit size in order to dimension, clean and "groove". Calipers and small squares of fresh 80 paper pinched over spinning stock chucked in a hand drill work fine. Then Burt's key was to take a simple Dremel-type conical burr (I use a 60 degree point) and chamfer the lip of the bores gently with said burr - just a few rotations - and only by hand. Even at just a few thousandths wide, this chamfer apparently gives the developing crown some place to go and helped eliminate several problems I was having (cracks OR loose pins that moved as I finished handle work). Oddly enough it does not leave a halo around the pin (in any material combo I've tried so far) as common sense suggests.

I realize a LOT of folks here use tapered reamers by hand assuming they get the same effect; to those folks I say if it works then keep doing it well. But to the new guys, I say get a practice piece together with your intended materials and tools, then bore twenty plus pin holes. Now ream half and hand-chamfer the other half and see which method fouls your scale material most often after you finish properly installing the twenty pins. Keep flipping your handle as you work the pins down in order to keep them roughly centered and keep in mind that the biggest goal here is to use many light taps AND stop peening just when ALL lateral pin movement is eliminated (I push my handle and proud pinheads down hard on anvil face trying to make them slip). I still use G/flex in pin holes because of the slow set and general quality performance. If you use CA glue as a sealant, then obviously all bets are off on this approach.

The difference in ductility in 300-series SS and 416 SS pins you mention is negligible to me. I have used both and honestly can't tell the difference at peening personally. Of course brass is obviously more ductile than either. Also you mentioned corrosion resistance so I suspect you're aware these SS need to be HT for max effect. Tall order on pin materials.

Hope this may help you sort out the issues.
 
Last edited:
With Corby's you can grind them to the length you want. Just custom fit them to the scales. They are hard to beat
 
Andy Lewis said:
Hey Aaron. Sounds like you you pretty much got it but still I have a couple of thoughts on pins and pinning:

Loose the claw hammer as mentioned. Buy a quality machinists ballpeen in the 2 to 4oz range - take it home and dress/polish both ends to 600x or better and dont use it for anything else but pinning. Both your control and finish will likely improve shortly.

Lock your elbow at side and use your wrist. Plan many light fast taps/strikes for each pin. And forget the ball end of the hammer when starting out. Your tiny pin diameter is the work's bottleneck; the flat polished face of the hammer gives much better control for proud pins (to be ground flush later) at roughly the same work per tap.

As important as the hammer, so is the anvil it sits on. Whatever your final choice, use the same one the same way each time. A hard face, backed up by mass, always wins on mechanical efficiency (why I use my main anvil FWIW). I have a decent bench block that gives good results with some practice but MY anvil just feels ideal to me for this ritual.

I would question the need (and time) taken to accurately counterbore pin holes in an effort to unify finished pin diameters. As Bill said, I don't expect G10 (or any common scale material) is anywhere near hard/strong enough to contain a hammer-peened pin head without distortion and/or radial crazing. The idea of the shouldered counterbore containing a tapered pin is odd to me personally but I have not tried it.

Burt Foster gave me some good general advice on pinning natural scale materials several years ago and I have cracked or fouled very few since. Basically I drill tang's holes slightly oversize, HT, epoxy first scale, drill first scale undersize using tang as template, epoxy second scale, back drill both scales at nominal. Then I turn down pin material a few thou below nominal bit size in order to dimension, clean and "groove". Calipers and small squares of fresh 80 paper pinched over spinning stock chucked in a hand drill work fine. Then Burt's key was to take a simple Dremel-type conical burr (I use a 60 degree point) and chamfer the lip of the bores gently with said burr - just a few rotations - and only by hand. Even at just a few thousandths wide, this chamfer apparently gives the developing crown some place to go and helped eliminate several problems I was having (cracks OR loose pins that moved as I finished handle work). Oddly enough it does not leave a halo around the pin (in any material combo I've tried so far) as common sense suggests.

I realize a LOT of folks here use tapered reamers by hand assuming they get the same effect; to those folks I say if it works then keep doing it well. But to the new guys, I say get a practice piece together with your intended materials and tools, then bore twenty plus pin holes. Now ream half and hand-chamfer the other half and see which method fouls your scale material most often after you finish properly installing the twenty pins. Keep flipping your handle as you work the pins down in order to keep them roughly centered and keep in mind that the biggest goal here is to use many light taps AND stop peening just when ALL lateral pin movement is eliminated (I push my handle and proud pinheads down hard on anvil face trying to make them slip). I still use G/flex in pin holes because of the slow set and general quality performance. If you use CA glue as a sealant, then obviously all bets are off on this approach.

The difference in ductility in 300-series SS and 416 SS pins you mention is negligible to me. I have used both and honestly can't tell the difference at peening personally. Of course brass is obviously more ductile than either. Also you mentioned corrosion resistance so I suspect you're aware these SS need to be HT for max effect. Tall order on pin materials.

Hope this may help you sort out the issues.
Click to expand...

Thanks! That was a good read!

The smallest hammer I was able to get at the local machinery place was 8oz, I'll also get a 3-1/2oz cross peen from Lee Valley tonight... As you said I tend to use the flat face more that the peen as I don't want the pins to expand right at the end because they start out proud.

I use west-systems epoxy when assembling my handles. When they get assembled the entire handle is already drilled and shaped as the majority of my blades are coated with Cerakote, and that precludes and grinding of the handle/tang after the coating has gone on...

I have done some cut-aways of the G10 after peening the pin in the counter-bore and the pin seems to fit the majority of the counter-bore quite well. It certainly forms a bit of a shoulder at the start of the counterbore and has proven to be a strong joint in testing. However as you said the counter-bore may be unnecessary and I should probably experiment with some counter-sunk holes and such also.

Luckily G10 is quite a sturdy material and is tolerant of a little over-peening. I just have to find the sweet spot with it.. I'll be experimenting tonight and we'll see how it goes!

Thanks everyone for the feedback so far!
 
Horsewright said:
Have you thought on Loveless bolts? Not quite as finished as a Corby but strong as heck. Used em on quite a few knives that went to the Sandbox. All handles stayed put. I recently re handled a friends knife for her, one I did not make. Peened pins and elk scales. The knife had been lost in a pasture for a couple of months and the scales were pulling away. One light smack with a hammer and they both fell off. Knowing the type of knives you like to make Aaron, think hard on the Corbys or Loveless bolts.
Click to expand...

I'm not a fan of the look of the loveless bolts unfortunately. I would be happy with Corbys, but it was clear after my experiment with 'mini corbys' that I would have to change to fasteners with larger head diameters and I didn't really want to do that... I very much like the simple clean look of the peened pins, if I can start getting them right consistently I'll be happy!

Do you know what the failure was with that knife that you re-handled? Had the scales expanded or something? In my experience peened pins are pretty tenacious about holding on if they're done right...
 
shane_o_ca said:
+1 for brass. Have you ever tried copper? Obviously very soft, and looks very nice on knife scales.
Click to expand...

Copper or brass would be ideal I think, but unfortunately wouldn't suit the look of the knives I'm making... I don't like to compromise based on aesthetics but sometimes the change would just stick out too much...
 
So a different thread just introduced me to JephCo as a supplier for hardware. They actually have some really nice Luke bolts in 3/16" that looks like they might be a good option!

It would definitely be nice to be able to forego the uncertainty of the peened pins. Especially seeing as I have to peen the pins while the epoxy is squeezing out and setting...
 
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