Spiral flute problem

[marvok]

Hello,i have made about 25 pens and have been happy with the results until, the last two have sort of sprial flutes insted of being smooth after being turned.Could anyone shed light on this problem for me?
This is my first question post,and let me say i apprieciate all that i've learned from this site so far.I would include a photo-no camera.
Thanks Marvin

 

[clewless]

I can do that on certain woods when I turn with my gouge. But when I move to the skew, I can get to a uniform smooth surface without diffiulty.

Is that a possibility here?

 

[mrcook4570]

By any chance are the spirals on the tailstock end? Make sure your chisels are sharp. Be careful not to overtighten the tailstock or the knurled nut. If all else fails, turn the blank on the headstock end, then swap it with the one on the tailstock end.

 

[marvok]

Thanks for the response,yes it is only on the tailstock end.
Marvin.

 

[mrcook4570]

The tailstock end has the least amount of support and is susceptible to whipping. If your chisels are not super sharp, you will be pushing harder to make the cut, thus deflecting the mandrel. It will start bouncing which creates the spiral flutes.

 

[marvok]

I'm in the process of sharpening now.
thanks.

 

[mrcook4570]

You can use the deflection of the mandrel to your advantage. Use sharp chisel to avoid sanding.

 

[JimGo]

That's cool Stan!

 

[pete00]

neat stan....

 

[scubaman]

Originally posted by mrcook4570
<br />You can use the deflection of the mandrel to your advantage. Use sharp chisel to avoid sanding.

This isn't April 1 any more, is it? Are you saying these spirals were made by 'chisel bounce'? Are you able to produce these at will, with no accessory, just by modifying the cut, or was this a one-time (happy) accident?

I'm not sure I follow your explanation, the tailstock end having the least support and most 'whip'. That's just not my experience. I know the effect, I didn't think it had to do with sharp or dull tools. When I've seen the spiral pattern it was with sharp tools. And once you got the pattern it's darn hard to get rid of it...

 

[mrcook4570]

Originally posted by scubaman
<br />
This isn't April 1 any more, is it? Are you saying these spirals were made by 'chisel bounce'? Are you able to produce these at will, with no accessory, just by modifying the cut, or was this a one-time (happy) accident?

I'm not sure I follow your explanation, the tailstock end having the least support and most 'whip'. That's just not my experience. I know the effect, I didn't think it had to do with sharp or dull tools. When I've seen the spiral pattern it was with sharp tools. And once you got the pattern it's darn hard to get rid of it...

It really doesn't have to do with sharp or dull tools, but how hard you are pushing against the mandrel. Generally, with dull tools, there will be more force against the mandrel, causing it to bounce. The same thing will happen with sharp tools as well, provided there is sufficient force against the mandrel. I've never been able to cut the spirals on the headstock end - only the tailstock end, so both halves are turned on the tailstock end.

I cut the spirals with a top secret tool (cheap chinese made spindle gouge []). It's kind of like a reverse chatter tool. Instead of the blade of a chatter tool bouncing, the mandrel will bounce. Sometimes the pattern is better than others, but done at will, yes. Sometimes there is tear out, in which case, I just turn bushing to bushing (I won't take the time to hand sand all of those tiny spirals).

 

[scubaman]

Originally posted by mrcook4570
<br />but done at will, yes.

Well that's pretty neat Makes a nice effect - I've done a pattern like this with much more effort once or twice on a spiraling jig, using a large diameter cutter

 

[gerryr]

I wonder if you could accomplish something similar by using a really small gouge, maybe 1/4" and having the tool rest 4-5" away from the work? It seems like it might behave somewhat like a chatter tool.

 

[btboone]

I've actually done that pattern on metal pens as well. It looks cool. Yeah, I meant to do that.[]

Besides, what wrong with spirals on a pen!?[]

 

[jdavis]

You need sharp chisels. Don't care what is said. Tailstock is too tight causing chatter. Students do it all the time and I have to correct it.

 

[mrcook4570]

Originally posted by gerryr
<br />I wonder if you could accomplish something similar by using a really small gouge, maybe 1/4" and having the tool rest 4-5" away from the work? It seems like it might behave somewhat like a chatter tool.

I would be afraid to try it - a catch with that much of a skinny tool hanging over the edge of the tool rest could possibly snap it (the blade of the tool), sending a 1/4" missile somewhere [B)]