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Modifying Exacto™ knife blades and permanent handles for them

By Vic Hamburger, Fri 21 Nov 1997

For those of you who enjoyed and tried my method of sharpening hobby knife blades, here is the second part of the series as promised.

Once you have become proficient at sharpening the blades, there is no reason to use only the metal handles. Having 3-4 different blades in front of you already sharpened and mounted in handles makes your modelling easier and faster. The hobby knives available have a good selection of shapes, but there are several more you may find useful as well.

First shaping the blades. A Dremel tool with a cutoff wheel is fine for changing the shape of a blade. USE A FULL FACE MASK while cutting these blades. When, not if, the cutting wheel breaks up, you want all the protection you can get. Full plastic shields are cheap insurance for your face and especially eyes. These thin cutoff wheels do a nice job but don’t force them, let them cut through the blades at their own speed.

One shape I find useful is the small, narrow blade that is a flat chisel shape with the edge 90 degrees to the length of the blade. I have narrowed this blade down from about 1/4″ to 1/16″ wide. This is useful for neatly chiseling off rivet heads, grab irons, etc from tight spots. Hold the blade in a vise and use the Dremel with cutoff wheel to slowly and gently cut a slot down the blade to leave the width you desire. Don’t let the blade get too hot. take breaks every so often to keep the blade cool. Once you have cut a slot the length of the blade, cut across the blade to remove the waste.

Once you have cut the blade, you can use a Dremel grinding point to smooth the cut side. A final polishing on the flat sides of the blade on the fine grit sandpapers will remove burrs and make them safe to handle.

A second blade shape that I have not made yet myself but I have been thinking about is to take a #11 pointed blade and trim back the point with an angled cut. This should still leave a fine point but with a bit more metal behind it for strength. If you hold the blade in front of you with the top, non-sharp edge horizontal and the blade pointing to the right, then think of trimming the blade tip back like this ‘\’ with the cutting edge extending all the way to the right but some of the pointed tip now gone. The leaves the cutting edge with the double bevel but a bit more metal behind it for strength.

To cut this one, use the cutoff wheel again with the blade in the vise. It should be a quick and easy cut, just don’t let the wheel hit the cutting edge. Come in from the back side to cut it off. About 1/16″ should be enough to cut off to give you the shape we are looking for. All you want to clip off is the bit of the tip where the two bevels are coming together.

Use your imagination and modelling skills to “design” other blades you need for your work.

To create permanent handles for these, use 3/8″ dowels. Use a course sander or hand plane or similar device to flatten three sides on the dowel to form an equilateral triangle cross section. You can leave some roundness between the 3 flat sides and then sand smooth. Cut the dowel to 6″ lengths and smooth the cut ends.

Saw a fine slot into one end, starting on the peak of one angle and going straight across to the middle of the opposite flat side. Keep this slot as thin as you can while still allowing a blade to be fitted into the slot. Mix a 5 minute epoxy (couple of drops each will do!) and fill the slot you just cut. Fit the blade with the cutting side DOWN toward the flat part of the handle. For a blade like the #11, this means the blade will rest with the cutting edge down and be ready to cut when you pick it up. When the epoxy hardens, finish sanding the handle, paint it if you so desire with some bright color so you can always find the particular knife you want with just a glance.

And you are done! Sharpen your blades once, keep them sharp by stropping them frequently and you will find your modelling goes more easily.

One last word on stropping…..the more you strop, the smoother the blade becomes until it reaches an optimum smoothness. You may have to strop a blade several hundred times on each side to get to that point but once you are there, 5-10 licks on each side of the blade will keep you sharper that you ever thought possible.

PLEASE, keep your fingers away from in front of the blade and don’t let little fingers try to cut with these! ALWAYS be safe when using these knives, they will cut clear to the bone if you get a finger in front of them.

Let me know if you have questions or to share useful blade shapes that you create!

Vic H

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