bolster problems

kile

kile

Joined
Mar 19, 1999
Messages
620
Does anyone have any tips for attaching bolsters. I have done several bolstered knives before, and have had very little problem. Lately the last two knives I have done have had a noticeable gap along the spine of the knife between one bolster and blade. I have never had a problem with this before, and from what I can tell I haven't done anything different from what I had done in the past. Also the last one no has a little gap where I peened the pin that looks like a little quarter moon. I have never had a gap around the pins before. I start peening the pins with a 16 oz. hammer, and then switch to a 3 lb hammer and bash the pin heads as hard as I can. I make sure everything is clean and flat before I start. What else do I need to do? Am I forgetting something or doing something wrong?
thanks for any help guys.
Kyle Fuglesten
 
There's some good info in the link.
Make sure the pins are really clean(acetone), as well as the holes, and of course make sure they are flat, as well as the area of the knife they are to be affixed to.
Make them a little oversized, and after the pins are set, smack the top edge of the bolster, followed by the botton edge, both sides. That will bend it down a little, and make up for any slight variance in flatness.
http://www.ckdforums.com/showthread.php?s=&threadid=4080
 
I haven't did a bolstered fixed blade in awhile, but when I did, I used a 1/0 or 2/0 tapered pin reamer. They have a 1° taper so when you hammer the pins down they expand and pull the bolster down.
Also, what Mike said about clean and flat.
 
As far as small gaps between bolster and tang (I suppose that is what you ment by 'a gap between spine and bolster'), if all things are not perfectly flat a couple smooth jaw vises can help. With tang sandwiched by bolsters, I have clamped the spine end in one vise and the belly side in another. Squeeze the heck fire out of them. Afterward, solder the bolsters.

Pinning gaps can be caused by warped bits and by sloppy spindles or chucks. In such a case cutting down on bit size by a couple mill can help. Usually our pins are in the numbered bit sizes, which makes it not difficult to drop down a bit size and remain within a very few thousanths. I am not trying to eliminate peening by suggesting this.
 
after you beat on it with the big hammer work them with the 16oz again. the heavier hammer will move more metal near the center and the little one with flare the ends better.
 
Also take the flats on bolsters and knife to at least 400 grit. Otherwise part of the line you're seeing may just be a sanding scratch.

Dave
 
I gotta agree with using a taper pin reamer. I think I originally picked that one up from one of Mike Hull's posts. It works like a charm.
 
What I use is,
Pin size
1/16" = 6/0 straight flute taper pin reamer.
3/32" = 4/0 ditto.
1/8" = 2/0 ditto.

I use dykem in the holes, because when I ream, I don't want the taper going all the way to the bottom of the hole, but to stop slightly short. With dykem and a magnifying glass, I can see how far I've gone, fairly easily.

Rick, I'm glad that worked out for you. Thanks for remembering.:D
 
Hey Kile. How's things?

Gordon (my former neighbor in Fargo - I just moved to Mankato) said he was going to look you up for a sandblasting job. Not sure if he got ahold of you or not.

Now on the pins and fit up:

Couple things come to mind: (if you know all this stuff, ignore it :D )

Are you using solder or JB Weld for the bolsters? If JB weld, clean it up with alcohol when you just start to mushroom over the pins. It gets trapped in there and leaves a mark every time.

Are you countersinking the pin hole in the 416? I tried that and always had a nice ring left. Don Cowles swears by it. I couldn't make it work so I don't do that anymore.

Are the pins longer than you've been using in the past? A little shorter is better than a little longer.

Polish up the pein on your hammer. It helps the metal flow smoother instead of tearing when peining.

Do you squeeze the bolsters flat to the tang using a vice grip or
C-clamp? Squeeze it all together just after you started to pein and the bolsters are starting to lock into place. Sometimes it just doesn't mash together tight by just peining it. Once the pins are slightly swelled up it will hold the bolsters in place after you've squeezed them. I notice this is more of a problem when the drill holes don't match up exactly.

Are the top edges of the tang flat or slightly rounded over?
Is the bolster perfectly flat? This one still gets me. Sometimes you can grind it down a little if the tang edge is just rounded over, but it really changes the knife outline - not always for the worst though.

Cork belt with green chrome can really smear 416ss and will hide a mark some times.

Hope you get it what ever it is. If you ever get a wild hair, come down to Mankato some time and we'll spend a day in the shop.
 
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