Wood discoloration near tip and bushings

Signed-In Members Don't See This Ad

Jay Sweeney

Member
Joined
Mar 21, 2016
Messages
14
Location
Sitka, Alaska
I have notices that, on some of my projects, the wood near the tip of the pen, or sometimes the center bushings of clip end, see to get a slight ring/area of discoloration. It is lighter in color and increases as I progressively sand through higher grits, starting at 400 grit or so. I have countered this by using a tiny bit of mineral oil, but the color of the wood still has a slight difference once I apply my finish. I have tried putting masking tape over the bushings, thinking that metal shavings might be a cause, but it doesn't really help that much. My wife speculates that it might as a result of be hitting cross grain, but I find the same thing when the tips are relatively flat. I read about wood singing by using barrel trimmers at high speed, but I still get the rings sometime when trimming at 500 rpm. I do note that some wood species are more susceptible to it than others - the pen I am turning today with the discoloration is plum wood (btw, a beautiful each color). Any ideas/suggestions?
 
Signed-In Members Don't See This Ad

Super Dave

Member
Joined
May 4, 2009
Messages
867
Location
Cape Coral FL
I would go with the bushings also. Light color wood can stain from sanding the wood and bushings. Another possibility is if you are burning the end grain when you square up the ends, some wood will burn if your barrel trimmer is dull or if you use a drum sander at a high speed, some will discolor on the end grain and that will show through also. What is the weather like up there, It was sunny and 82 while I was putting up Christmas Lights.

Good luck, Dave
 
Last edited:

KenV

Member
Joined
Oct 28, 2005
Messages
4,720
Location
Juneau, Alaska.
Jay -- if you are using a pen mill at 500 rpm (that is about 20 times the speed I use a sharp one at) you are either taking a lot of material off, or you are burnishing and heating the ends of the pen. Heat will cause discoloration of the wood from the end, and may affect the glue joint to the tube at the end. Glues soften about 150 degrees F in most cases.

Metal is generally seen as black specs in light wood. Discoloration is either contamination , heat, or similar and is other than black specs. Have you looked at it under magnification such as a 10X Loupe?
 

jttheclockman

Member
Joined
Feb 22, 2005
Messages
19,082
Location
NJ, USA.
Heat is definitely possible because it is the enemy when it comes to making pens. But my take on it, and you did not specify the kits you are using, would be that the ends closer to the bushings is being turned down farther than the center portions. In other words the thinness of the material maybe showing the tube through or gets very close. You get a lot of change in colors like that when turning acrylics. At the nibs and cap ends it is thin as compared to center portions and if you really leave some bulges then it shows even more. If you even out the thickness may help to make it more uniform. Just my simple opinion.
 
Top Bottom