How to get tight bolster fit?

matus

matus

Joined
Apr 24, 2009
Messages
662
Hi, I just tried to make my first brass bolster for a puukko knife. In other words I needed to get a rectangular opening with exact dimensions. I first drilled a few holes with 2mm drill, than used thin round file to connect the drilled hole and then a small flat file to get a rectangular opening.

The problem is - the blade thickness at the ricasso where the bolster is supposed to sit is the same as the thickness of the tang (3.5mm with this blade). At first I had the width of the opening in the bolster OK, but until I got the other dimension right (so that the bolster could slide all the way down ) I inadvertently increased the opening also in the other direction. This resulted in a gap between the bolster (once in place) and the blade sides. It is just a fraction of a millimetre, but you can imagine how it looks.

My question is - how to solve this problem? Is there an easy way to keep the width of the slid in the bolster untouched while working the other direction, or should I file the thickness of the tang down a little so when I make a new bolster this gap does not show?

Thank you in advance.
 
Using a "safe" file will help with this. That is a file that you have ground off the teeth on the sides. I have several that have the teeth ground off different sides.

To fix your problem, you might be able to make a ball pien punch and make a line down the sides of the hole. This will push material into the tang slot. You will have to grind the face of the bolster, but it doesn't take as much as you thing.
 
Just in case no one else answers:

The only thing, in my little experience, is to make sure the bolster hole is slightly smaller than the width of the tang to begin with. Work with a micro file a little at a time until the tang fits into the bolster hole with no gaps.

Some(out of the few ive done) of mine have turned out great, some I got careless and the gap is noticable. It'd be great to have some kind of reverse file guide.
 
That's funny. Yea. I've watched them in the past but had a 12 hour night watch last night and crushed all of them. Really good stuff but they take a while to get through. I think in the 2 bolster fit up videos he'll answer the ?'s you have.
 
Thanks, I will definitely go with the tapering + see what Nick has to say :)
 
You don't lose anything by tapering the tang slightly, strength wise.


An out of the box way to do this would be to heat the guard up a little, which will expand the metal open the hole and all it past a close fit on the tang. But it might be hard to do this more than once.
 
I just want to say that all your advices did not go in vain. I have just a put a slight distal taper ono the tang, worked more carefully with the file and now I have bolster that slides down to last 2cm (thickness difference of about 0.2mm) from where it should sit. Once I get the shaping and finishing of the front surface done I will gently hammer it in the place. I have also slightly widened the gap on the handle side of the bolster, so once that it will be in place I will be able to put there a little bit of epoxy for peace of mind.

And those videos are great. I will be re-watching them form time to time as there is too much information to absorb in one go. I also have to admit that I am starting to get the point about stuff like belt grinder, disc sander, or band saw. I have just spend 1.5 hours to get just the bolster to fit on the tang the way I want it and to get it roughly (with file) shaped. And it is not anything fancy.
 
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