Turning Archive 2006

Subject:
bowl gouge grinding instructions for Al

TDaniel
>The first thing to remember when setting up a grinding jig is that the jig alone will not give you the desired profile, no matter how it is adjusted. The jig will give you a starting (nose) angle and an ending angle (side). The jig will help blend these two together. Notice I said the jig will help, not do it for you. Since there are no stops on the jigs metal will be removed as long as you hold the tool to the grinding wheel and if metal is being removed then the profile is changing. Keeping these things in mind put a tool into the jig and allow 2 1/8" to extend out, (make a gage so you can always return to this setting), set the nose angle or side angle. ( I start with the nose angle but I think the instructions advise doing the side first.) After setting one move the tool and set the other, then go back and check the first; each adjustment will affect the other. Now before grinding you must have in mind what you want the finished tool to look like. The grinding requires a lot of hand/eye coordination. I like to start a new gouge by turning it upside down and shaping the end like I want it. Just put the flute against the flat rest of the grinder and put a convex shape on the end of the tool and carry that shape back about the same distance as the diameter of the tool shaft. Then return the tool to the jig and grind until the cutting edge reaches the flute all the way around; you'll have to readjust the tool in the jig using the gage block a couple of times as you sharpen the tool the first time because removing a lot of metal on the end will change the amount of tool extending beyond the jig. Once you have ground the edge until it meets the flute you have to look for high spots where the tool shape isn't like you want it and grind the high areas off. You cannot put any metal back on so if you see a low spot you have to leave it be and grind the other part down to the low area. It is all hand/eye cordination. Look at the "Grinds" library and strive for the angles and profiles pictured. I would start with a side grind about the same length as the diameter of the tool shaft and use that for a while. Later you might want to play with the length of the side grind but get used to the tool first. Be aware that some flute shapes are harder to sharpen than others. I like the shape of Sorby and One-way better than others. Also be aware that a very small change in the distance to the wheel or the amount of tool extending from the jig will make a BIG difference in the profile.

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