Odie
Panning for Montana gold, with Betsy, the mule!
Hard dry Eastern birdseye maple.....
=o=
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This is what you want guys......
- Thread starter Odie
- Start date
Odie
Panning for Montana gold, with Betsy, the mule!
Once you find that "perfect cut" you'll see that it isn't dependent on faster rpms, but rather can be found along with the best vibration free rpm, in conjunction with sharpness and presentation......
The rules are different for cross-grain bowl turning than they are for spindle turning. If you can find the PC, you'll notice that you can turn the rpms way down, and still achieve it......as long as presentation and sharpness is maintained. The dynamics of a bowl shape will negatively react increasingly more to higher speeds the further from that point which is determined to be the best vibration free rpm. There is definitely a limit to how slow it can go, just as there are limits to how faster speeds will sometimes create conditions that result in a better cut. (IMO, newer turners will almost always resort to higher speeds mainly because they wait too long between sharpening intervals.....or, they just haven't developed their sharpening/honing skills to a fine degree.....yet!
Also, the established formulas for determining the best rpm are only a starting point. Each piece of wood will have its own unique best vibration free rpm, and there really isn't a set rule for finding it. Using a "vibrometer" has been a significant help in my efforts to find the PC......but, it should be understood that this little device is not a "silver bullet"!......it is dependent on the refinement of other turning skills for it to work well, and is only a "piece of the puzzle" in finding the best rpm applicable to any one individual bowl.
=o=
My vibrometer is shown here. I've modified it slightly from the photo, but it's use is the same as the configuration in this photo:
Here is a link to the discussion that led to the development of my first "vibrometer"...
The rules are different for cross-grain bowl turning than they are for spindle turning. If you can find the PC, you'll notice that you can turn the rpms way down, and still achieve it......as long as presentation and sharpness is maintained. The dynamics of a bowl shape will negatively react increasingly more to higher speeds the further from that point which is determined to be the best vibration free rpm. There is definitely a limit to how slow it can go, just as there are limits to how faster speeds will sometimes create conditions that result in a better cut. (IMO, newer turners will almost always resort to higher speeds mainly because they wait too long between sharpening intervals.....or, they just haven't developed their sharpening/honing skills to a fine degree.....yet!
Also, the established formulas for determining the best rpm are only a starting point. Each piece of wood will have its own unique best vibration free rpm, and there really isn't a set rule for finding it. Using a "vibrometer" has been a significant help in my efforts to find the PC......but, it should be understood that this little device is not a "silver bullet"!......it is dependent on the refinement of other turning skills for it to work well, and is only a "piece of the puzzle" in finding the best rpm applicable to any one individual bowl.
=o=
My vibrometer is shown here. I've modified it slightly from the photo, but it's use is the same as the configuration in this photo:
Here is a link to the discussion that led to the development of my first "vibrometer"...
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Odie
Panning for Montana gold, with Betsy, the mule!
In my opinion.....some enterprising soul is going to make some money if he can design and market a good usable vibrometer to the woodturning community!
I've found that the thick ponytail bands used in the photo above are too strong, and I'm currently using thinner ponytail bands. I've tried several types of plain rubber bands used for office work, but didn't find anything that worked better than the thin ponytail bands I'm currently using. There might be a better band for the purpose, but so far I haven't found anything that works better.
Possibly something like a very large thin o-ring might work better, but I haven't explored that possibility......???? All I can say, is my homemade vibrometer works, and I use it on every bowl I make in search of the PC.
If I were younger, I might partake in a little capitalism myself.....but, at this point in my life......all I'm interested in doing is working in my own home shop, producing the bowls that I make.
=o=
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