I always amazed at just how effective shop made jigs can be. With a small investment in time and the knowledge of how they work to be most effective, anyone can build jigs like this sharpening jig and get good results. Years ago I purchased a somewhat expensive commercial sharpening jig, and it works well and is very versatile, but you know what? When I first set it up to sharpen my blades at 25 degrees angle, I have not adjusted it since then, so all the extra settings and things it will do, I have never used. The sharpening jig I am making in this episode is equally adjustable, but most people who make it will probably do the same thing I did, set it up to sharpen at 25 degrees angle and leave it there because the results are just what we need.
To start off making this jig I used a piece of dowel that was 1-1/4 inche in diameter and 4 inche long. That lenght seemed to a nice size that would accomodate all my blades and still have room for something larger if I ever acquired it ...
The remaining parts I would need included a couple of short lengths of redi-rod in 1/4 inch threading, and couple of matching T-nuts and wing nuts, 2 flat washers and 12 inch length of scrap wood about 4 inches wide and 12 inches long.
I started off by drilling 2 recessed holes in either side of the dowel. This is probably the most critical part so take your time whether you are on a drill press or using a power drill. The forstner bit I used is a 3/4 inch because it needs to accommodate the bast of the T-nut. The holes need to be vertical into the dowel and it's best to use a fence to make sure that even if the holes are off a bit, at least they are both off which will help make sure your jig works fine. You will also need to make sure the holes you drill are going to be deep enough that the base of the T-nut sinks below all the wood of the dowel. By that, I mean if you loop down the length of the dowel after the T-nuts are installed you should not see any metal from the T-nuts, this is important because if you so see metal, your jig may not give the exact results in sharpening that you want.
After you drill the holes for the T-nuts, if you have some sort of a vice of clamping device, with your dowel still in the that clamping device you can now drill the holes that will allow the collar of the T-nuts to slide into.
Before you install the T-nut, take a moment to make the cap for the jig. I made mine 1-1/2 inches wide and 4 inches long. Now take your dowel that you have already drilled and use it for the guide to drill the 2 holes in the cap. Make sure the holes are as centered on the cap as you can get them.
Next you can install the redi-rod into the T-nuts and hammer them home into the recessed holes you drilled in the doweling. Double check to make sure the T-nuts are below the wood on all sides. I used a lock tight product to secure the redi-rod inside the T-nuts, but glue would likely work fine too, it will just take longer to dry and harden.
At this point you can assemble the sharpening jig, because next you will be making the alignment jig.
The alignment jig is fairly simple, but again, you need to be working with good, square, flat wood. Make an estimation where you want to cut the "V" in your block of wood. The "V" is going to be 45 degrees on both sides and will be exactly 90 degrees from the edges of your board. You could use a sliding mitre to cut these if you have a depth adjustment, or you could use your table saw with the blade angled at 45 degrees.
The next part of the alignment jig will be attaching a side to it. The side is very important component because it is what you will use to make sure your blades are set at 90 degrees in the sharpening jig.
To set up the distance block on the alignment jig, I found the easiest was to cut a small wedge at 25 degrees to use as a guideline so do this before you do the final step.
The final element of the alignment jig is the measuring block. You will first need to take some time to align a blade in your sharpening jig using the 25 degree wedge and aligning it as best you can. If your wedge is too big or too small you may need to make another (I had to make 3 before I got one that worked best for me)
It is conceivable that you may be off by a degree or so, but that will be inconsequential. The main goal here is to get the angle as close to 25 degrees as you can, as long as you use this jig with what you set it at, your blades will be just fine.
Now to use the jig, all you do is slide your blade or chisel into the slot, tighten slightly until you have it adjusted up to the stopper, and also have the side of the chisel or blade aligned with the side of the alignment tool, then finger tighten and you are now ready to sharpen that tool ...
Copyright - Colin Knecht