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Thursday, November 21, 2013

Turn A Turner

Turn a turner.
I just couldn't help that corny play with words. I turned a spinning top.
I searched high and low for a suitable photo of what appears in my mind when I think of a spinning top. Somewhere buried deep in my memory is a metal spinning top very similar to the one above. It was painted up like an alien space ship.
So that may explain why I chose the shape I did for my first turned spinning top.
This was one of the kits that Ms. Clause sent me. I chose a piece of a rosewood block that I had cut off to make a bowl a while back. That left me with just enough to drill a hole in to make a little stand for it to set on.
The instructions give several good ideas for shapes of a top. I'd like to order some more of these kits and try a few of them. For the first one though, I had to go back to what my memory told me a top should look like. I wasn't sure how it would work though.
I guess it does pretty good. With a good pull, it spins about two minutes before toppling over. This was plenty enough time to get a good photo of it in action.
I enjoyed this project and definitely hope to get the chance to do some more of them in the future.
This is the bowl photo you seen a couple of days ago. It is the one I had all the problems with. Well after posting that blog, I got a couple of emails from some good friends who know more about turning than I do. It was apparent to them from that blog post that something was very wrong. Somewhere, somehow, my technique was off to a point that they were a little concerned about me and wanted to offer suggestions.
So I asked questions to try and figure out what was going on here. I seemed to be doing alright, besides a few high speed projectiles that seem to occur in my shop for unknown reasons. Next, I looked over a couple of books I have on techniques.
I couldn't figure it out. However, there was one area that always bugs me, my tools. I have read countless opinions and seen even more countless out of control arguments about the correct sharpening angle for this tool or that one. For my spindle tools, I am perfectly satisfied. For bowls though, I was going good, but still wasn't satisfied that it was right.
So back to square one. What is the correct angle for a bowl gouge?
Sixty degrees?
Fifty degrees?
Forty degrees?
Thirty eight and three sixty eighths degree with a side of bacon?
Seriously, if you get online and try to find an agreement on this question, you'll find it, until you look at a different source.
So what is right?
The only thing I knew for sure was that it was time to try something new. I done a search online for the instruction sheet for several different commercially available sharpening jigs. After looking at these, it seemed that it seemed to be a general consensus with these jigs that a bowl gouge should be ground at about a forty degree angle.
Above, on the left, is one of my gouges before regrinding them. As I said, it was getting the job done well, but something just wasn't right.
The one on the right is the new grind angle. I wouldn't say it is exact, but is very close to forty degrees. The question is, or was, would this change in grind angles make a difference for the better? Or worse?
Well there was but one way to find out.
This is a hunk of wood off the same block as the bowl you seen in the earlier photo. After all, I wanted to compare apples to apples here, not apples to apple sauce.
I think it made a huge difference. It seems that less of an angle causes less tear out, and a much more controlled cut.
Also, in this photo, on the left is shavings from before the regrind. It actually looks more like course saw dust than shavings. On the right is the shavings from the test bowl with the new grind angle.
It turned out like cutting butter with a hot knife. I actually wanted to go a tad thinner. The bowl as you see it is just under a quarter inch thick. I started to see hairline cracks when I stopped the lathe to check the progress though, and decided I had better not push my luck.
So what angle do you grind a bowl gouge? I have no idea. I'm going to stick with this grind for a while and see how it works out for me. It looks very promising. If it turns out to be a problem though, I think I will change it on the word of the, I believe, best advice I have heard so far. A man on another blog told me once about sharpening tools, "If what works for other people don't work for you, change it until it does work for you."
With that said,
Till next time friends, happy turning!

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