View Full Version : Bolsters wiggling around before peening

Jim T
08-21-2010, 08:35 AM
I'm trying to fit 416 stainless steel bolsters onto a full tang knife. I've drilled 1/8" holes in both the bolsters and the blade for the pins. I'm finding my 1/8" pins fall right through the holes rather than fitting snuggly.

As a result, the bolsters wiggled just enough that they ended up slightly crooked when peened onto the blade.

According to my calipers, both my drill bit and my pins are exactly 1/8" in diameter.

Should I be gluing the bolsters to the blade prior to peening? Or should I be using a slightly smaller drill bit on the blade and bolsters to make the holes more snug?


mike miller
08-21-2010, 09:06 AM
I would get some needle nosed pliersand hold the bolsters steady on the spot. You also need a taered reamer to make sure when the pins expand they pull the bolster closer to the side of the blade to help lock it in place.

joe levy
08-21-2010, 01:16 PM
If you have resharpened your drill it will drill oversized if it is not ground evenly on each lip.

08-21-2010, 02:00 PM
Something isn't right....a 1/8" pin will not fit into a 1/8" hole (both the hole and pin SHOULD be .125"), and unless the hole is slightly larger, the pin will not fit, even if you try to force it/drive it in. If your 1/8" pins are falling through holes drilled with a 1/8" bit, then it's likely a cheap import bit, which often can vary +/- .003-.005, or a bad sharpening job. I know this because I used to buy the import bits because they were so much cheaper....I quickly learned to purchase USA made HSS or Cobalt bits if I wanted them to be accurate.

Personally, I use 3/32" pins for attaching bolsters, no matter how large the knife or bolsters. I use a #41 drill bit to bore the holes. (for 1/8" pins a #30 drill bit should be used) Although it might sound counter intuitive, you need a LITTLE room between the pin and hole so that the pin will expand evenly when peened. It also helps to counterbore the holes in the bolsters a few thousandths larger, so when you peen the pins, they develop a "head" that will be below the surface of the finished bolster(s). (sort of turns the pin into a rivet, with a head on each end).

Finally, the front (the part facing the blade), and the back (the part that the handle material butts up to), should be completely finished before installing the bolsters. BUT, life is considerably easier if you leave the bolsters over sized top to bottom. Short of spot welding a bolster in place, it WILL move very slightly during peening. Usually it's never enough to be noticeable, but if the bolsters are completely finished prior to install, it becomes blatantly, and painfully obvious.

Rudy Joly
08-21-2010, 03:11 PM
If the chuck on the drill press isn't true, neither will your holes be true.
Also now that I'm going half blind, I check my drill bits against my pin stock with a micrometer or vernier just to be sure. I once drilled a blank with a 5/32 drill bit and all my 1/8 pins fell through too. Double check everything and get glasses if you need them. I'm about to take my own advise and get away from the cheaters.


Jim T
08-24-2010, 08:45 AM
Thanks guys.

Ed, I'll invest in some quality drill bits. If that's all I require then that's an easy fix. Rudy, I'm crossing my fingers and hoping it's not my drill press chuck becasue that'll be more of an annoyance to tend to.

By the way, Rudy, I already wear glasses. Didn't stop me from trying to put the wrong set of scales onto a knife. Duh. Maybe I just need to get more sleep.

Thanks again for the suggestions and advice, guys!


08-25-2010, 11:41 AM
I cheat,I put my bolsters on with the pins through and then put my file guide behind the bolsters butted up tight,then peen.Helps keep them from twisting and keeps them aligned.

08-26-2010, 04:44 AM
I don't think it cheating Stan I think it is a clever plan.

08-26-2010, 07:07 AM
Stan, I agree, that's NOT cheating...that's brilliance!! The difference between a "Knifemaker", and a "Great Knifemaker" is that the Great Knifmaker knows how to overcome problems, and hide/eliminate their mistakes! Just like that little trick!

08-26-2010, 08:34 AM
Thanks Guys,I also took a piece of 1"X1" solid bar and welded some ears on it so it sits in the hardy hole of my anvil to peen against to clear the file guide.Maybe this will help someone else.

John Barker
08-26-2010, 08:52 AM
That's a great idea.

To make sure all my holes are in line, I usually lay out the bolsters and where I want the holes on one side. Then, I clamp both bolsters to the blade in the proper position and drill straight through all three pieces. I do this before tapering my tang. Then I finish the front and back of the bolsters with all my pins in the holes to keep both side aligned. Ream the holes with a tapered reamer. Clean my pinstock by hand with alcohol and a Scotchbrite pad. You have to make sure the side touching the blade is flat too. This is very important to have flat bolsters that are clean, and pins that are clean. As I put the whole thing together it is usually pretty snug. I always use at least 3 pins. Then, smack them with a 3 lb hammer. You need the sudden force of a big hammer to really make the pins expand. You don't just want to peen the head, you want the whole pin to expand. Watch your gap too. You may have to squeeze them in the vise in between blows, until they really snug down. Be careful not to hit the front or back edge or your screwed. Hope that helps.

Jim T
08-26-2010, 10:44 AM
Ingenious guys! Thanks for suggesting all the clever techniques. Can't wait to try them! Might help me cut down on wasting steel.

Every time I work on a knife it's a learning experience. Sometimes it's an, "Aw, crap!" moment, but more often it's an, "Oh, wow!" moment. So far, the wow factor is way ahead. Are we having fun, or what!


08-30-2010, 10:36 AM
I noticed you asked if you should glue the bolsters as well. Imo, you should use both chemical and mechanical methods of attachment so I'm going to say yeah on that one. I wouldn't recommend the expoxy found in common stores though, and you'll need somebody else to tell you what to use as I don't know:/.

John Barker
08-30-2010, 11:57 AM
The bolsters are held in place by the flaring of the pins. You don't need any adheasive. It will only keep your bolsters from fitting as tight and from looking as good. If you do them right, the only way to get them off is to grind them off.

09-06-2010, 11:22 AM
The bolsters are held in place by the flaring of the pins. You don't need any adheasive. It will only keep your bolsters from fitting as tight and from looking as good. If you do them right, the only way to get them off is to grind them off.

I can testify to that. I had an accute case of Idiot and peened a set on and didn't complete a step in the process and had to drill them off. The pins had compressed all the way to the tang.

09-06-2010, 11:36 AM
I posted this in the tutorials section a while back. It may help or give you something to look at.


09-06-2010, 11:13 PM
Well I should make a great knifemaker. All I have is problems. I spend most of my time trying to overcome those problems.:biggrin: Just kidding about the part of one day being a great knifemaker. As old as I am and no more time than I have to devote to it, I will doing good to make an average knifemaker.

Good idea on using the file guide. I am sure going to use it.