January 5, 2013
Plans are now available for this jig, see them here
Chisel / Plane Iron Sharpening Jig
A few months back, I received an email from a reader asking if my planer knife sharpening jig could be adapted to sharpen chisels and plane irons. I did some
experimenting on that jig and made an adjustable tool holder for it, but I found that the eyebolt / threaded rod pivot point was a bit too tippy for something as narrow as a chisel. It would need more support to keep it level and true. I put it aside to give it some more thought.
Weeks pass before I get back to it, and this time I have a new idea. It's simple, but one of those things that can be evasive if you are thinking on a different track. Instead of a single eye bolt as the pivot point, I made a slot that the tool holder fits in. It lets the tool holder move freely, but holds it on a flat, level plane.
Here's the completed jig:
I made a video showing the assembly process:
I used good one side (G1S) plywood to make mine. A high quality plywood like Baltic birch can be used, but is not strictly necessary. It's important that the plywood be a uniform thickness, smooth and flat.
The parts that form the slot are glued, pinned and clamped onto the base:
I then set this aside to dry for an hour.
While the glue was drying on the base, I cut out the template parts using the full size templates from the plans:
The slot was cut on the drill press, drilling a series of holes. This can be done on a router table as well, or with a jigsaw or scroll saw.
The tool cradle is assembled:
There is more detail on this part of the assembly in the video above.
To hold the stone in place, wood strips are glued to the base:
The stone I'm using (and recommending) is a Norton crystolon-India combination, medium silicon carbide (grey side) for fast cutting on the hardened steel. The fine aluminum oxide (orange side) produces a keen edge and is hard wearing. It's a good idea to use a hard stone for this to prevent premature or uneven wearing.
With the assembly finished, it's time to use the jig.
After setting the angle on the tool cradle, a chisel is clamped in. A guide stick is used to locate the chisel properly:
The drawing above details the guide stick. It is just a piece of straight hardwood with a notch at one end. The depth of the notch matches the distance from the top of the stone to the bottom of the tool cradle. This should be 1/8".
Here I'm working on the primary bevel of a 1-1/2" chisel:
After a few minutes work I have a chisel that is ready to use, or it can be taken to the next level by polished it on a compound-loaded buffing wheel or strop.
This jig can be configured to work with any size stone. You can even make your own by gluing wet / dry sandpaper to a piece of plywood, as shown below. This is handy for taking the edge up in grit levels, if you are after that super, razor sharp edge:
The stone that I use in this jig is Norton Item# ICS8. This is a fairly low priced, but very good quality stone and is readily available.
There are also similar versions that are 1" thick (mine is 3/4" thick) and to use this thickness, the plywood under the slot will have to be built up. Whatever thickness stone you do use, the bottom of the tool cradle should be 1/8" above the top of the stone.
It can be used with diamond stones too - the thin plate type can be made thicker with plywood, double sided taped to the plate.
For whatever type of abrasive you use, I would recommend using a thin oil rather than water, since the jig will stay in better shape it it doesn't get wet. If water must be used, I recommend giving all of the parts two or three coats of polyurethane to seal them.
Here's a video showing how to set up and use the jig:
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I have already used this jig several times, getting some of my older, much abused chisels in top shape. I have two block planes and the irons on these have never been sharper.
Thanks for reading,