Jig Components
The components of the DIY Grinding Jig are shown to the right. They are a long gouge rest, an adjustable platform rest and a fingernail jig. The long gouge rest is used by rotating the gouge handle in a vee while grinding the tool tip. The angle of the grind is controlled by the distance of the vee from the grinding wheel. The adjustable platform rest is used to grind scrapers and skew chisels. The fingernail jig is used along with the long gouge rest to produce a fingernail profile on spindle or bowl gouges. The main requirements to build the jig consist of a length of 2" x 1" planed timber (44mm x 22mm ?) about 4ft (1.2m) long, a short length of 2" x 2", some scraps of plywood and an assortment of M6 screws and nuts and woodscrews. |
Jig Components
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Component Clamp
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Jig Clamp
The grinder should be mounted on a thick board and a clamp arrangement is built under the required wheel. (A similar one may be positioned under the opposite wheel if desired.) A length of 2" x 1" (approx. 6" or 150mm) is sawn in half lengthwise to provide two narrower strips of the same depth as the 2" x 1". The front end of the outside strip is reduced slightly in height by sanding. These strips are then assembled around a length of 2" x 1" with a piece of plywood on top to give a smooth sliding fit. This can be helped by sandwiching some paper under the plywood. The whole assembly is screwed to the base board using three woodscrews as seen on the left. The front outside screw should be an M6 coach screw inserted from under the board (in a recess) with a washer and wing nut above so that the plywood can be squeezed on top of the sliding 2" x 1" to give a firm locking |
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Long Gouge Rest
The long gouge rest simply consists of a length of the 2" x 1" timber (approx. 30" or 750mm should be enough) with the end sawn into a vee shape. The length should be sufficient to accomodate your longest gouge so that the correct grinding angle may be achieved against the wheel. Two small pieces of plywood are pinned and glued to the vee so that the tool handle sits comfortably in the angle while it is being rotated. This jig is ideal for roughing gouges and for square ended bowl gouges. |
Gouge Rest
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To use the jig, it is necessary to slide it through the clamp until the correct grinding angle is set. This can be checked by applying a marker pen to the tool bevel and rotating the wheel by hand (unplug the grinder !!). The marker should be removed in a strip from heel to tip when set correctly.
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Adjustable Platform Rest
The adjustable platform rest is made from two short lengths of 2" x 1" timber of a combined length suitable to reach the centre of the grinding wheel. They are clamped side by side by a screw and wing nut and the lower piece is pinned and glued to a longer length of 2" x 1" which slides in the jig clamp. A piece of plywood (or MDF) is pinned and glued to the end of the top piece so that the whole becomes an adjustable table on which to rest tools to be ground. The front edge of the table should be chamfered underneath so that support can be given as close as possible to the grinding wheel. The picture to the right should show the general arrangement.
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Platform Rest
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Fingernail Jig
The fingernail jig is made from a short length of 2" x 2" timber which is cut away at the lower end so that a shaped plywood leg is in line with the centre of the wood. The two are hinged together so that they are clamped by a screw and wing nut. A 3/4" hole is drilled through the wood along the same direction as the plywood leg (see pictures). This hole is to hold the tool being ground and the screw to fix the tool in place passes through a hole in the top end of the 2" x 2". This is an M6 screw with a wing nut locked against the screw head by an ordinary nut. Inside the larger hole, the screw is fed through another nut (preferably square to grip the upper edge of the hole). The picture shows the assembly. After inserting the tool to be ground under the now captive screw, the screw can be tightened into the tool flute thus pulling the square nut into the top of the hole and gripping the tool tightly in the jig. The jig is used by locking a gouge in the tool hole, setting the required angle between the top and the leg of the jig and locating the leg in the vee of the long gouge rest before swinging the whole arrangement while keeping the tool tip in contact with the grinding wheel. The various adjustments consist of sliding the long rest in the jig clamp, the amount that the tool protrudes through the jig and the angle between the leg and the toolholder. Unfortunately, setting any one will tend to disturb other settings so it will be a matter of trial and error. Fundamentally, the position of the long rest sliding in the jig clamp will mainly affect the angle ground on the side wings of the tool. the angle of the bevel on the nose of the tool is mainly controlled by the protrusion of the tip and the angle of the leg. It is recommended that, once suitable settings have been discovered, these should be recorded and kept. It is a simple matter to mark the required angle of the leg across the two parts of the jig. The protrusion of the long rest can be marked on its arm and the protrusion of the tool tip can be marked against the edge of the base board. |
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Disclaimer
We will keep it short :
EVW take no responsibility for damage or injury caused as result of following the above project procedures.
Readers carry out all tasks at their own risk. |
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