Turning Archive 2006

Subject:
Belt Sander Sharpening -- REVIEW (long) *LINK*

Brad Vietje
>Since writing this response below, I thought it might get lost, and maybe not noticed by some here, so I decided to re-post as a review piece. In the review below, I am specifically referring to Jon Siegel's sand & buff sharpening system, which can be seen at Jon's site, which also has some great illustrated articles:

FWIW, I've used Jon's sharpening system, as have a lot of turners in northern New England. I've done turning demos at local symposia with this sharpener, and often mention hom much it simplifies and de-stresses the sharpening process. I like it a LOT, so I'll add some review comments below:

What Jon's done is to offer a relatively affordable machine that does most of what Woodcraft's old (and long-ago discontinued) Mark II system did. He uses a 4" wide belt that travels UP, away from the cutting edge. Any rounding (from the belt riding on a thin cushion of air) happens at the heel of the tool, where it is very desirable, but not on the cutting edge, which would be terrible. This is, BTW, the biggest reason for inverting the belt travel. He uses a 60-grit belt for re-shaping, and a 150 grit belt for sharpening. After the tool is sharpened, there is also a thin buffing wheel for de-burring the edge with tripoli or emery, which also polishes the flute a bit, which can help with the edge on many less expensive tools that have slight ridges inside the flutes.

Jon Siegel's system is very quick, very accurate and entirely reproducible. He uses a "V"-block to capture the end of the tool handle, and there are many indexed positions for placing the V-block quickly so you get the same grind each time. For fingernail grinds and bowl gouges, he also offers a stand that replaces the V-block so there is enough room to swing the tool through the arc to acheive the fingernail grind without hitting the indexed baseboard.

The main feature of this system is that you can sharpen and buff a tool about 7 SECONDS, literally. Bowl gouges or fingernail grinds will take 20 seconds or so, because you have to attach the Ellsworth jig or equivalent. This system also produces perfect flat bevels, which Jon also prefers. That's a debate for another post...

BACKGROUND: Jon has taught turning for nearly 40 years, and is considered a top turning "guru" in greater New England. He is a big proponent of using "muscle memory". He has described this as the learned motion of hands, eyes, ears, tool, bevel angle, speed, etc, that are required to get just the right fluid cut on a particular piece. This is built up during roughing cuts, and he teaches that just before your final cut (ultimately the only one that really matters), you want a very keen edge on the tool in use to get the smoothest finishing cut and reduce sanding (which no one likes, and which can distort detail and isn't healthy, either...). If I turn away from my lathe to sharpen or hone my tool and have a frustrating time with a sharpening session, or the process takes too long (read: Tormek), you will lose any aquired muscle memory, and your final cut will be no more accurate that your roughing cuts. I have also seen my dad (when he was alive and turning) and many other turners get all frustrated at the grinder, and turn back to the lathe a few minutes later to ruin a number of pieces because 1- he was now frustrated; 2- he had been away from the workpiece too long to "remember" what smooth, fluid motion he needed to make; and 3- his tool and bevel were not the same shape they were a few moments ago. Turning after frustration could also be said to be dangerous as well. This appears to be a very common problem, especially with beginners, who are VERY likely to struggle with dull tools because sharpening is either not easy or too stressful.

How it works: Assuming I have my V-block set for the tool in my hands (the tool handles and V-block positions can be numbered or color-coded to make that quick, too), I turn away from the spinning lathe, sharpen and buff the tool in about 7 seconds, and I'm right back at my workpiece. The worn 150 grit belt produces a very fine edge which in my view almost never needs to be honed. You will never see a system that's easier and more reproducible for skews, and a slightly curved skew is a real pleasure to sharpen.

As for repeatability and accuracy, there will be a very slight change in the bevel angle as steel is removed from the bevel, since the tool gets a tiny bit shorter. However, unlike other sharpening systems, very little steel is removed. A very light touch is used, and the difference between a sharp tool and a dull one is maybe half of a thousandth of an inch (o.ooo5"), so with a light touch, you can sharpen a tool 2000 times before you lose an inch of HSS. The change in bevel angle is thus very slight and imperceptibly slow, so after a few hundred sharpenings, you can always change v-block positions, or attach something thin to either the V-block or the handle to hold an angle.

When I had very little money, I made a sort of similar system out of a 12" disk sander, with a V-block and indexed positions. I also established positions for my Ellsworth and other fingernail jigs. I'm now pinching pennies again, having just bought a house, but as soon as I can afford it, I plan to buy one of Jon's machines. It doesn't do everything, but everything it does do it does better and faster than any alternative I've yet seen.

That's just one fella's opinion,

Brad Vietje
Newbury, VT

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