KnifeDogs.com & USAknifemaker.com Owner
In this laughably crude drawing we'll try and figure out how to make your bolster pins not show. Like just about everything in knife making there are lots of ways to do things. If some one has any suggestions, comments, jump in!
Use the same material. Mixing 416ss bolster material with some other kind of stainless is guaranteed to have the pins show.
Use a tapered pin reamers
These create a cone shaped hole and not the typical vertical hole left by a regular reamer or drill bit.
You don't ream with this all the way. Just partially. If you need to, grind off the extra length at the tip of the reamer. You want a partial cone shaped hole.
In normal piening (peening?), most of the force from the hammer blows are vertical and depend on the pin to expand enough and blend into the metal surrounding it.
When you grind it down after piening, much of the actual blended material is ground off near the very tops of the holes.
Piening into a cone shaped hole has the force of the hammer blows smearing the metal into the sides of the cone shaped hole. This action has the pin blend into the sides of the cone. When you grind the bolster to shape after piening here, the metal is blended all the way to the bottom of the cone.
A couple other things.
Clean the holes free from dykem, oil, cutting fluid.
Sand the oxidation off the pin material. All stainless has a surface coating of oxidation -- that is what makes is stainless.
Polish the face and ball of the hammer. It will move metal easier instead of tearing it when piening.
Use the flat side of the hammer for most of your piening. It seems you should use the ball side but the flat side works better - with just a little practice.
I use a 3lb maul when I am done piening and smack it like crazy a couple times for good measure.
I now use a pin press: http://mickleyknives.com/html/page_29_pin_press.html
It's MUCH easier and I get much better results more often. cool 1
I now only get pins that show 1 out 6 or 7 knives. If I have pins or rings showing, I grind the bolster off and start over. :bud: