Blade radiusing jig for Tormek...
John Aniano in Central NJ
>Hello All,
Well, here is my blade radiusing jig in all its simplicity. It took all of 30 minutes to make. I thought about the design for a few days before cutting and drilling. The drawing shown below is a courtesy to those who asked about how the jig was put together. As many of my friends have noticed, I usually use Post-It notes for my "engineering" drawings, but for this jig, I simply drew on the scrap pieces of poplar I had on hand. In fact, the overall size of the jig was based on the scrap dimensions. You could make the jig larger or smaller to suit your needs or grinding setup.
This jig came out of a need to put a radiused edge on block plane blades (I use #102 planes for roughing cuts in bowmaking) as well as for sharpening scrub plane irons. I had been using the regular plane/chisel jig Tormek includes. I had been loosely positioning and clamping the opposite end of the blade just inside the jig "jaws" so the blade could pivot and produce a radiused edge. I've done this for ~2 years ever since I discovered the #40 scrub plane. (One of my most favorite tools, but that's another story...) The jig shown here is an outgrowth of the clamp/pivot idea.
The jig shown above is somewhat adjustable; the hex head pivot bolt can go in two places; you could drill more holes for more positions. The jig rides on the Tormek arm; it simply slides on and off the arm. Once the blade is clamped, the jig is slid onto the Tormek arm and the bevel angle set by moving the arm in or out. I usually use my Tormek with the wheel spinning away from the edge being shaped, as the cooling water doesn't go all over the place. Once grinding, you simply hold the jig base steady and rotate the whole blade in its clamp to put a radius on the edge. You can slide the jig around so you don't grind too much on one place on the wheel. For honing, I take the blade out of the jig and do it freehand. I have never bothered to rotate the Tormek, reset the arm and use a jig for honing. It's just faster for me to do it freehand. Note that the blade is upside down in the "photo" above - I put it that way to show the radius...
The blade is held between two 3/8" thick poplar pieces ("A" and "B") which are clamped together using a �-20 flat head bolt, washer and thumb screw. (In the image above, the clamp piece "B" has been removed.) These two clamped poplar pieces then rotate against the larger �" thick base. They rotate via a hex head pivot bolt held against the base somewhat loosely by a pair of jam nuts; you could use a locknut to do this. The hex recess was cut using a small gouge; I got it close and simply hammered the bolt head flush into place. The more I think of it, you really don't need to make a hex recess; the bolt head simply needs to be flush with the surface of the blade clamp "A". I could have used (2) flat head bolts to assemble the jig (I had only one flat head bolt but lots of hex head bolts). You can see the circular "wear" marks on the base piece so I applied some candle wax between the base and clamp "A" to keep things from binding.
Is this radiusing jig overkill? Well, yes and no. Since it took me about half an hour to make - the answer is "no". Should I master the technique to hold the blade freehand to put a radius on the edge? Yes, but since I'd be using the Tormek to sharpen these blades anyway, this jig may be a nice compromise.
Over and out,
John