Dark band after turning

[kenlholley]

I have noticed that on several of the pens that I' turned that there is a narrow dark band at the ends of the turned blanks. It almost looks like the wood was burned during the turning. When I first notice it I thought it was from sanding too aggressively but the lines appear as I turn. I use a carbide tool that is very sharp. Any ideas of what might be causing this?

Thanks for any help.

 

[Dave Turner]

I've never seen this. Is it burnt wood or is it some kind of contamination that you can clean off with denatured alcohol? How are you holding the ends of the blank? Are you using bushings? If the blank is slipping on the bushings while you turn, I imagine it's possible to develop friction heating on the ends or possibly accumulate contaminants.

 

[kenlholley]

I'm turning on a mandrel with bushings. The band will not wipe off. I've tried sanding it off but no luck. I lock the blanks snugly in position, but I guess it is possible they are spinning on the bushings creating heat. I'll try snugging them a little tighter and see what happens. Thanks for your help.

 

[TBCbushings]

I had that happen to me too...I sharpened my tools and it went away...Dull tools is what it was for me....Hope this helps.

 

[Sandy H.]

Just to double check: Do you use CA to glue your tubes in and if so, does the CA penetrate the wood and soak in? I had that happen on one pen, but I use epoxy now and that solved both of my issues.

Just a thought.

Sandy.

 

[ed4copies]

Quite possibly you are moving metal from the bushings to the ends of the blank.

Particularly if you turn from the ends, in to the middle.

Metal particles will appear black or very dark grey on wood.

FWIW,
Ed

 

[Tim'sTurnings]

I've seen the dark bands on the ends of the blanks before. They were from burning the ends by using a barrel trimmer that was dull. It was burning the wood and cutting very little. That could be your problem if you are using a barrel trimmer that is dull.
Tim.

 

[Ambidex]

Quite possibly you are moving metal from the bushings to the ends of the blank.

Particularly if you turn from the ends, in to the middle.

Metal particles will appear black or very dark grey on wood.

FWIW,
Ed

+1..my first thought..and it embeds and almost impossible to get rid of..

 

[PenMan1]

As others have said, my first thought would be metal shavings contamination caused by sanding over the bushings.

IF THIS IS, indeed the case, pay very close attention (use calipers) to the next pen you make with these bushings as it could be overturned if you cut to the "new", smaller bushing sizes.

 

[PenMan1]

FWIW:
If it is bushing shavings, putting the pen barrel between centers, sanding with 600 grit with the lathe running in reverse, followed by a CA accelerator cleaning will SOMETIMES make the rings go away.

If your lathe has no reverse feature, spin the lathe backwards by hand while sanding. This makes the "nap" of the wood go the other direction and MAY release the tiny bits of trapped metal dust.

 

[bybill]

If you don't have a reversible lathe you can 'reverse sand' by turning the blank(s) end for end and remount. Works for me!

 

[1080Wayne]

If you don't have a reversible lathe you can 'reverse sand' by turning the blank(s) end for end and remount. Works for me!

And me !

 

[Falcon1220]

You are generating to much heat while drilling your blank.

 

[montmill]

When I used triple E and metal bushings that would happen.
Montmill