Getting Steel Pins to weld in Steel Bolsters

C

celluloidheros

Joined
Dec 31, 2008
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Hello, I have a question related to pocket knives and bolsters. When you peen a Nickel silver Pin into a NS bolster it magically peen-welds and leaves a seemless bolster where once polished you can't really see the pin at all.

With steel Bolsters and pins however, I have a problem where 99% of the time I can't get the pin to peen-weld to the bolster. I have tried different types of steels from coat hangers to nails etc... Cleaning both the pin and bolster is very important and I have found that acetone works the best.

Rat tail and similar bolsters seem to be even harder than normal flat bolsters

Can anyone share their secret to steel bolsters.

Thanks, CH
 
The most important thing is to be sure the pin material and bolster material is the exact same steel. IE if you are using 416 for your bolsters, which is what most are using these days, you MUST use 416 for the pins.
I typically drill my holes in the bolster material then use a slightly oversized drill to flare the top of the hole so that the pin has something to pein into. You can also ues a tapered reamer, if you have one available. Cut your pin material so that it is just less than the distance through your bolsters and tang + just less than twice the diameter of the pin stock. In other words, if you are using 1/8" pin stock, you should have just under 1/8" sticking out on each side. I use a ball pein hammer with the ball side polished up as smooth as possible. This will help keep the pin from splitting when you pein it. I also have a small peining anvil that I have drilled a couple of 5/32" holes 1/4" deep into. Once I get both sides of the pin to pein over enough to hold the pin in place, I set the bottom side of the pin over the hole and set the top side of the pin down to help tighten the bolster down and better fill the hole in the bolster face. I then turn the knife over and set the pin on the anvil face and pein the loose side again. I keep repeating the process until everything is tight.
That's what works for me!!

Steve
 
Steven Kelly said:
The most important thing is to be sure the pin material and bolster material is the exact same steel. IE if you are using 416 for your bolsters, which is what most are using these days, you MUST use 416 for the pins.
I typically drill my holes in the bolster material then use a slightly oversized drill to flare the top of the hole so that the pin has something to pein into. You can also ues a tapered reamer, if you have one available. Cut your pin material so that it is just less than the distance through your bolsters and tang + just less than twice the diameter of the pin stock. In other words, if you are using 1/8" pin stock, you should have just under 1/8" sticking out on each side. I use a ball pein hammer with the ball side polished up as smooth as possible. This will help keep the pin from splitting when you pein it. I also have a small peining anvil that I have drilled a couple of 5/32" holes 1/4" deep into. Once I get both sides of the pin to pein over enough to hold the pin in place, I set the bottom side of the pin over the hole and set the top side of the pin down to help tighten the bolster down and better fill the hole in the bolster face. I then turn the knife over and set the pin on the anvil face and pein the loose side again. I keep repeating the process until everything is tight.
That's what works for me!!

Steve
Click to expand...

This is good reading Steve. Thanks for sharing.
 
#1 they don't weld, its just that the gap between the two pieces is so small that you can't see it easily with the unaided eye.

I think this comes down mostly to a question of malleability; however hard NS may seem it is much softer than any steel alloy you will use. Because the NS is softer it is easier to force them together so that there appears to be no gap. The steel is harder and requires more force to get to that point and the level of force required may be above the point where it causes distortion.
Thanks,
Del
 
I agree on the matching of the steel pin to the bolster. The other issue that was hit on is the hardness of the material. I take quite a while to look for the pin to completely cover the countersink. More than once I thought I was done only to see the ring when finished.

The nickel silver fills the void very easily but you really have to work the edges of a steel pin to get it to fill completely. I do work around the edge of the pin. I have had some problems where the stainless of the bolster and pin although sold as the same clearly were not.
 
The other reason it works so well with Nickel silver and other non-ferrous metals, is in the polishing. The metal flows ( somewhat similar to a Beilby layer) and virtually washes the joint smooth. Iron and steel act differently.
Stacy
 
Another hint is to make sure there is NOT any kind of lube in the hole when you put the pin in it. If there is there will ALWAYS be a ring around pin.
 
I can see that on New knives you can know what the pin and bolster material are. What is you are repairing an older knife and do not know what the bolster material is ? Does anyone have experience with older knives and have any suggestions on what material to use as pins ? Like I said before, believe it or not finishing nails and coat hangers have worked the best for me. Also how about on cleaners used to clean the pin and hole. I use acetone and a little dental brush to clean the hole.

I really want to thank everyone for their help and responses.
 
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I repair a lot of knives, and use common nails when a steel pin is needed. I turn them to whatever size is necessary. Coat hanger wire is useful, too.
Flush riveting is a little different than peening rivets. The rivet needs to be hit hard enough to upset it into the taper or countersink, rather than just peening the head with light taps.
BTW- I saw on another thread that you are of the "Case family." I also, am one of those!
Bill DeShivs
www.billdeshivs.com
 
Old thread, trying to resurrect it to see if there is any new info. I am trying to figure out what material old knife mfgs used for steel bolsters. They seem to be Cast steel, low or medium carbon. I'm assuming it would be less that .5% carbon. But I'm not exactly sure. And knife manufacturers may use slightly different materials. I am buying some low carbon wire and also some nails. The diameter of the Nails is in the .060 to .100" range that I need.

I have found the getting the whole pin to expand and not just the head mushroom is critical. I have not decided whether pin pin is actually welding or galling.

I'd like to find a material such as nails or wire that is available and works to repair old steel bolstered knives. so fair a simple finishing nail that is uncoated works the best.

I use acetone to clean the pin and bolster hole, we use a reamer to prep the hole. We use a hammer and prepare the edge to hit all around the pin.

What I am working on now it hitting the pin straight down the axis with a larger hammer to expand the pin deeper into the knife and not just getting a surface mushroom. If anyone has solved this issue for old knives, LMK. We are at about 25% success rate.
 
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with stainless i have found the inside of the hole and the outside of the pin being smooth and shiny contribute most to the pin disappearing. you can roll a tiny piece of 600 grit into a tube and smooth the inside of the hole. ( i do 3/32" pins) i do 600 grit on the outside of the pin. i had ordered stainless pin stock from a few places, they all had a rough surface on the outside. they were gray/ scaly looking, with shallow pits.. i put the full length pin in a drill press chuck and pinch the sandpaper around it while it turns. not all of them disappear, but i have a much better success rate now. maybe 60%.
 
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