Mammoth ivory bark and bolsters

[Frank J Warner]

This is a fit and finish question.

I'm working on a series of folders, several of which will have metal bolsters and mammoth bark scales, the real pretty kind ($) if ($) you ($) get ($) my ($) drift.

I like to have a smooth transition between the scale material and the bolster. You should not be able to feel the joint when you scrape your fingernail across it. With most materials this is not a problem; assuming the bolster and scale material are flat and about the same thickness at the beginning, you simply contour them both at the same time, as a unit, while they are attached to the liner.

However, the pretty part of mammoth bark appears to be about one molecule thick. Any grinding at all and the color that took 10,000 years to develop is gone. The bark that I have has a reasonably usable convex contour already, although it's not perfectly symmetrical. The main thing is to preserve the colors on the surface of the bark, even near the bolster.

To top it off, I prefer to make a dovetail joint between bolster and scales.

Here and here are pretty good examples of what I'm trying to do.

So, my question, after that long-winded explanation, is: How do I grind the bolsters to fit the ivory, knowing that I can't grind the ivory at all, while still ensuring a flawless fit?

I suspect the answer is, "very carefully," but am hoping somebody has a better method.

Thanks,

[TexasJack]

Let me preface this by saying that I haven't done it and MORE than welcome a correction by someone who has. It would seem to me that you're looking at it backwards. It will be hard to grind the bolster to fit the mammoth. I'd suggest you do the bolster to the size you want, then slowly and carefully grind the BOTTOM of the mammoth scales. (Grind a little, check fit, grind, check,....). After the depth is right, then drill the holes and finally trim the outside.

Am I on track with this? :confused:

[Frank J Warner]

Originally Posted by TexasJack

Am I on track with this?

Not really. I'm aware that I have to remove material from the back of the ivory to make it the right thickness. But the outside or front surface of the ivory is rounded -- a section of an arc cut from the animal's round tusk -- and I have to round the metal bolster to the exact same arc for the two pieces to match, without touching the front of the ivory with any abrasive.

[striper28]

Frank,
I have done this quite a few times but each one is still tricky. Basically what you have to do is make the handle material and the bolster the same thickness. Then with only the bolster attached to your liners radius it to match the radius on your ivory. I try to get it as close as I can with a belt and then use a hand file to get it to match. I'll file some and then check the ivory against the bolster, then file some more. It takes longer this way but it keeps you from sanding off all of the color you paid for.

The other thing you can do is to bevel the front of the ivory till it matches the same height as the bolster material after you have radiused it. You don't want it sticking up too much, but just enough for it to gradually meet the bolster. I have attached pics of both ways I have described it done. The sunfish is the second way described.

Let me know if you have any other questions.
Chuck

[TexasJack]

I have to round the metal bolster to the exact same arc

Ahh! Sorry, I didn't catch that in your original post. (and should have!)

[Frank J Warner]

Originally Posted by striper28

I have done this quite a few times but each one is still tricky.

Excellent explanation, Chuck. I was pretty sure it involved lots of work. Just wanted to confirm that with someone who'd actually done some of it.

Thanks.

[Mitchell H.]

Originally Posted by striper28

Frank,
I have done this quite a few times but each one is still tricky. Basically what you have to do is make the handle material and the bolster the same thickness. Then with only the bolster attached to your liners radius it to match the radius on your ivory. I try to get it as close as I can with a belt and then use a hand file to get it to match. I'll file some and then check the ivory against the bolster, then file some more. It takes longer this way but it keeps you from sanding off all of the color you paid for.

The other thing you can do is to bevel the front of the ivory till it matches the same height as the bolster material after you have radiused it. You don't want it sticking up too much, but just enough for it to gradually meet the bolster. I have attached pics of both ways I have described it done. The sunfish is the second way described.

Let me know if you have any other questions.
Chuck

Wow, that top knife is a thing of beauty

[Anthony Chaney]

So is that bottom one. Kinda reminds ya of a stubby little cigar, don't it.