Saturday, February 18, 2017

Carbide Turning Tools

There is a big schism in the wood turning world over the use of carbide turning tools and traditional High Speed Steel tools. Some people use both, but most seem to lean towards one or the other, and it ends up being one of those 'CD vs. Vinyl' sort of arguments between the 'old school' and the 'new hottness'.  My main turning tools are the mid-level set of HSS from Harbor Freight, which is to say they are about the worst tools that you can actually call 'usable'. That was the set that I started with when I bought my lathe. Since then, I've added a couple of Benjamin's Best brand gouges which are, by most accounts, at the lower end of  'half decent'. Basically, the next step up. These are all High Speed Steel traditional turning tools (gouges, chisels and scrapers). But I kept hearing about these new carbide tipped tools that never need sharpening and by some accounts are suppose to be very easy to use. They are, however, expensive. The carbide tools start at about $65 and easily go over $100, each. The tools I buy now are closer to $20 each.

But the carbide tipped ones are basically a tool handle with a steel shaft and a replaceable carbide cutter that attaches to the tip with a screw. I can make a tool handle. A piece of 1/2" square bar stock will serve as a shaft. All I really need is the replaceable cutter which, as luck would have it, sells for about $20.

I turned the handle out of soft maple. I drilled the end out to accept a piece of square bar stock, which I epoxied into the handle. I used small pieces of copper pipe as ferrules.  Most people who make their own handles for these, cut a recess in the tip of the bar stock, so that the top of the cutter sits flush with the top of the shaft. I don't see the necessity in that. I just set my cutter on top of the bar stock. I drilled and tapped a hole through the top of the shaft near the tip. Then I marked the outline of the cutter, so that I could remove any excess material from around and under the cutter's edge.
I got three different tips; a round one, a square one, and a pointed (diamond) one. There are other shapes, but these are the basic ones. The tip of the shaft has to be rounded on the underside so that the bar stock doesn't get in the way when it is up against the work piece on the lathe. And some of the material at the tip has to be ground down to let the cutter's edge protrude past the edge of the bar stock. Once the cutter was attached to the shaft with the screw, I also put some CA glue around the back edge of the cutter to help hold it to the shaft without twisting or moving at all, and to prevent the screw from working its way lose from vibration. If I ever need to remove the cutter, I'm sure I can break the CA bond without much difficulty.


That's really all there is to it. Turn handle, insert shaft, add ferrule, drill and tap, shape tip, attach cutter. Done.

Having used them a few times, I'm not really all that impressed with them. I won't count them out just yet, but so far I like using traditional gouges better than the carbide tools. I guess I'm just Old School.

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