Grinder platform angle setting jig

Sharpening is one of the essential skills for woodturning. Most turners use a grinder to sharpen tools, but each type of tool needs a different grinding angle. For example, a skew chisel will usually have a more acute angle at its edge than a roughing gouge, which in turn will have a keener edge than a scraper.

Each of these tools (though not bowl and spindle gouges) can be ground while flat on either the grinder’s own tool rest or a separate platform rest, which just has to be set to the correct angle. One way to do this is to blacken the existing tool bevel with a marker pen then adjust the platform until the bevel comes into full contact with the wheel, which is inched round by hand so that the ink removed will show the accuracy of contact. Or you can just match the bevel to the wheel by eye, looking from the side. But in either case, any error can be cumulative. It will be repeated and possibly amplified next time the tool is ground. This can lead to a gradual change in the bevel angle.

I use an easy to make grinder platform angle setting jig that gives a consistent, repeatable result very quickly. It consists of a scrap of plywood with two projecting screw heads that align it to the wheel rim, and a straight edge at the bottom to which the platform can be set. The jig is very easy to make and use. A different one is needed for each tool type and thickness (thicker blades contact higher on the wheel rim and because of its curvature will be ground to a sharper angle than thinner ones). Use plywood thick enough to take the screws in its edge without splitting, but no dimensions are critical. All you have to do is set the platform angle as you wish, perhaps copying an existing tool angle, then cut the plywood so it rests on the platform with its edge fairly close to the wheel rim. Insert the two woodscrews (as far apart as the wheel guard and platform will allow, and angled so they are radial to the wheel axis. Drill pilot holes to prevent splitting.) The screws can be turned in or out to fine tune the fit. If necessary, the inner edge of the plywood can be cut away to follow the wheel rim more closely.

To use the jig, loosen the platform, place the two screw heads in contact with the stationary wheel rim, bring the platform into contact with the bottom of the jig and tighten up again. Every time you sharpen the same tool, or another of the same blade thickness, the angle will be just the same, making for quick results and saving tool life.

Grinder platform setting jig

 

About Terry

Terry Vaughan has been a woodturner for many years. He specialises in finely turned domestic items, as well as making components for globes. He is keen to help other turners and has provided some great resource pages on his web site.
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4 Responses to Grinder platform angle setting jig

  1. Bob says:

    That’s a nifty jig. What I want to know is how to set the platform to a different angle than the one that on the chisel now.
    Thanks, Bob

    • Terry says:

      Thanks Bob. You have to decide the bevel angle you want, adjust the platform so it grinds that angle, then make the jig to fit. Then the jig will let you put the platform back to that exact position anytime. Usually the bevel angle isn’t critical – what you need is repeatability, which the jig gives you. Also, the hollow grind from the wheel means the exact angle at the edge is hard to measure.

      To change to a different angle, you could saw a bevel at the angle you want on a bit of wood, then use that to set the platform. It would have to be about the same thickness as the chisel. You would lay it on the loosened platform, adjust the platform by hand until the bevel contacts the wheel properly, then lock the platform.

      I haven’t seen Eddie Castelin’s jig. Mine can be fine tuned, but you do need a separate one for each angle. I used them for a long time, but recently I’ve changed to one of Reed Gray’s platforms. That can be set very quickly with an indexing pin, if necessary while the wheel is turning. The angle changes in 5 degree increments, which is quite acceptable in practice.

  2. Bob says:

    I thought the jig you have was the one I saw long ago on capt. Eddie Castilin. It was made of plexiglass and each angle had its own plexi gauge.

  3. Bob says:

    Thanks Terry, that’s a good idea.

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