Need help contouring handles

K

Keegaroo

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Jun 26, 2011
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I just recently got started into knife making and completed my first project last week and have started a new one. My trouble is grinding/sanding the scales (in my case Micarta) to the round profile I'm looking for. I read to grind at about 45* degree angle to make a sort of pyramid then sand it but am still having trouble. Any advice is greatly appreciated and I'm working with mostly hand tools and using a Work sharp and dremel tool as my stock removal tools, also I am using .1875 in. Micarta scales.
 
Keegaroo, a dremel is a lousy tool for handle shaping, in my experience.
Grab a couple full-size files. NEW files, ideally. You'll be shocked at how effective they are.
After files: sandpaper. (I start at 180 and go up as desired)

-Daizee
 
I do have a set of files that are relatively new and thank you for the advice. Technique wise stick with what I'm trying now or is there a better way?
 
Many years ago when my grandfather was showing me how to use a draw-knife he said "you can turn an octagon into a circle but if you try to start with a square and go straight to a circle you end up with an oblong".

Go from a square to an octagon, then 16 sided, then round or oval as you prefer.
 
There's probably better recomendations to be had but what works for me as a novice is my 1x30 belt sander to get the handle bevels and rounding started. I adjust the tool rest to about 30 degrees or so and bevel the entire outside edge of the handle slabs. I'll do a little free form shaping on the belt sander to round the edges off a little and rough shape it. In the end it really comes down to learning to use the files then hand sanding. I resisted for the longest time because hand filing/sanding takes alot of time and patience. I'm learning, though, that time and patience equate to better end results. Some guys just have an eye for symmetry and others of us have to get alot of practice before figuring out where to remove material so both sides of the handle match and give you the contours you're looking for.
 
The longer and wider grinding surface (whether that be sanding blocks, files, rasps, etc.) you can use the better. Using a 1" wide filing medium along a 5" long handle = 6 or so overlapping paths. A 2" wide medium will be 3 paths. The less the number of paths the more even things will be easier.

Gawd, that sounds retarded, but I know what I mean. :D

Trying to use the tiny drum sander on a Dremel with it's 1/10" wide surface contact makes getting the handle even a lot more difficult than using a 2" wide belt grinder.

Also, I try to go length wise (butt of the handle to the front of the handle) with a hard block somewhere around 120 grit. If you can get everything even at that grit level, past that I find it's fairly easy to keep everything even. Even if I contour a handle in and out towards the tang, I still do this. It lets me know I'm starting with even sides. Once you start contouring, it's harder for me to tell if everything is even.

I hope that helps somewhat.
 
Thank you all for the help and will definitely try it out. I have one last question how deep do I need to file and at what angle and should I leave a flat part where the scale makes contact with the tang?
 
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Some while back I put some photos together of how I shape handles, I use hand tools almost exclusively. Not sure whether they will be of help since you are starting with thinner stock and are probably going for a thinner handle overall, but you might still find something of use.

Spyderco Bushcraft Handle Tutorial


Best of luck:)
 
I do most of my handle stuff on a 4x36 sander, on the contact wheel. I can shape pretty well, and if you take it slow, you can get it shaped pretty well. I'll do rough shaping that way, and then hand sand to get the contouring where I want it to be. I use Mark 1 eyeball to make sure it's appropriately balanced.
 
I agree with using hand tools.

If you really want to get a precise shape, there is a mathematical way to do it. I start out by squaring the handle scales with the tang. Then I trace my top view profile on the handle and remove material down to the line, keeping the surface I'm creating perpendicular to the top. At this point the handle will have contours when viewed from the top and side, but each cross section will be rectangular.

Now suppose you want the handle to have circular or elliptical cross sections. In geometry if you took a rectangle and then drew an ellipse inside of it so that the ellipse just touched the midpoints on each side of the rectangle, you call that inscribing the ellipse. What you will actually do is create an octogon such that the ellipse is also inscribed within that. That sounds complicated, but really you are just going to create bevels on the corners. The math is to let you figure the width and angle of the bevel so that it exactly matches the shape (circle or ellipse), and create lines to file to.

Basically, you pick several points along the length of the handle, and measure the width and height. Make sure you pick the narrowest and widest points, and at least one point in between these. I draw horizontal lines (perpendicular to the length of the blade) across the top and sides of the handle at each point, creating a grid. Now for the height (from the side view) take the first measurement and divide it by (2+SQRT(2)). If the height was 1 inch, the result would be ~0.29". That's how far down the side of the scale from each corner the bevel needs to come. I use the depth guage on dial calipers and make a mark 0.29" from each corner, on the grid line for the first measurement.

You would do the same for the width (from the top view), but on a full tang the shape here is not going to be a perfect ellipse or circle. It will be a circle/ellipse "interrupted" by a rectangular section (the tang and liners). You need to subtract the thickness of the tang + liners from the width measurement you took earlier. So if the width at the first measurement was 0.75", and the tang with liners was 0.1875", then you need to do the calculation for an ellipse with a width of 0.5625", which when divided by (2+SQRT(2)) gives you 0.2197". So on the top and bottom of the handle make a mark .22" from each corner, along the gridline for the first measurement.

You repeat this process for the rest of the measurements and end up with a series of marks on each of the gridlines. Now trace a nice arc that connects all of the marks near each corner. These lines will be the tops and bottoms of the bevels you need to file. If you look at one corner, at the first measurement the line on the side should be .29" down from the corner, and the line on the top/bottom should be .22" away from the corner. If you file away everything between those two lines it create one face of the octogon. The width of the bevel will change as the height and width of the handle dimensions change along the length of the handle. Once you file down all 4 bevels you will have octagonal cross sections everywhere.

Now, you can take this further and create a 16-sided polygon by repeating the process, and you would have to make new measurements for the new faces on the octogon, and make 8 sets of marks at each gridline. This time you need to divide the measurments by 3.848...

While the more bevels you create the more accurate your shape can be, it's really not worth it to take it this far with the math. Just take down the shoulders of the octogon at an angle that roughly bisects the angles of the two faces that form the edge. Take it down until the bevel you're creating is about half the width of the two faces that formed the edge. At this point it should be easily rounded with sandpaper.


I'm not saying it's necessary to do it this way. I'm not sure if I'll do it again. I've done two knife handles like this and I thought they turned out well. One of the first handles I did totally by eye and it looks good, but if you hold it at certain angles you can tell it's slightly off kilter. The math is a way of minimizing mistakes like that, at the expense of time and tedium.
 
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