Sharpening Plane Irons, Jig SE-77
Patents: SE 531 802, EP 1987916, U.S. Des. D651,884 S
With the SE-77 Square Edge Jig, it is easy to set your wood chisels and plane irons for sharpening to a square corner. The design gives you the best conditions for a successful sharpening with the highest precision over the final result. You can also set the jig for a slightly convex shape.
The SE-77 Square Edge Jig is a further development of the SE‑76 jig. It has been provided with an adjustable side that can be set with the help of two smaller knobs, which allows fine tuning if needed. This can be required if the tool is not exactly square to the stone, is very narrow or if the steel is slightly twisted. The setting for fine adjustment is done in seconds by loosening one of the smaller adjustment knobs and tightening the other.
The jig's construction also makes it possible to position and sharpen tapered chisels, e.g. Japanese chisels. The safety stops keep the jig securely on the Universal Support and prevent the tool from sliding off the grindstone, so there is no risk that you will hurt your fingers when sharpening. The jig fits wood chisels and plane irons up to 77 mm (3") width.
Sharpening a convex shape
Most types of plane irons can benefit from a slight convex shape. The degree of camber depends on the type of plane and should be approximately the same as the thickness of the shavings. Thanks to the adjustable side on the SE-77 jig, you can achieve the optimal convex shape for your tool.
When sharpening a convex shape, center the tool under the jig's center line mark.
The more you loosen the adjustment knobs A and B, the greater the pendulum motion you get, which increases the convexity.
Steady mounting and safe grinding
The jig lines up the tool to its upper and flat side. Thanks to the jig's shoulder (A), it is easy to mount the tool correctly at 90°. The clamping pressure from the ridge in the centre is distributed to the edges, which gives a steady positioning of the tool in the jig, without having to force the locking.
The jig comprises an upper base with a lower clamp and two locking knobs for fixing the tool. The jig slides on the Universal Support on nylon bushings across the grindstone. The edge angle is set with the Micro Adjust (3) on the Universal Support (4).
There are two safety stops to prevent the tool from slipping off the stone when grinding. One inner stop (1) to be positioned according to the width of the tool and one outer stop (2) mounted on the end of the Universal Support.
The jig lines up the chisel to its upper flat side, making it easier to mount it correctly (not twisted). Conventional jigs need manual alignment.
The lower clamp has a ridge in the centre enabling shorter tools with a tapered shank to be firmly mounted, e.g. Japanese chisels. The upper base, which lines up the tool, is designed so the clamping pressure is distributed to the ends and the tool mounts firmly without a heavy tightening of the knobs.