Help with segmentation

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orlandopens

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Oct 9, 2012
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Location
Orlando, FL
I have always admired the segmented and scalloped pens posted on this forum and recently tried turning my own using blanks that I have glued up of various wood species separated by aluminum bans. I've had the glue lines fail on several of the blanks, always on the aluminum or brass bands. I may have forgotten to scuff the metal before gluing up the blanks (rookie mistake) but I am also wondering about the glue. I use a two part, five minute epoxy on my blanks. A little sloppy but I like the extended work time. Is there an advantage to using CA over epoxy?

Also, I finish my pens with CA after sanding to 12,000 grit. I have this process down pat. But on the segmented pens, the aluminum and brass bands come out dull. Is there any way to polish them before applying the CA that won't discolor the wood?
 
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If your glue joints are failing you may be overheating the metal as you drill it. Old glue may add to the problem.
 
Those blanks are very hard to assemble Ken...I love doing segmented pens!!!! and use both copper and aluminum. CA...IMHO is to brittle once cured. Drilling and sanding will cause "normal" epoxy to delaminate due to heat buildup. Look for a High temp epoxy, I use System 3, but I'm sure there are others out there. With these kinds of blanks it is crucial!!! to make sure the thickness of the material and your bandsaw blade match. Not so much with straight cuts, but with any curve…those must match!! If you are using CA as your finish…don't worry about "staining"…they will match in the end! If you're using anything else, shellac or WOP will work well as a barrier. Again…they are tough, but beautiful when done.
 
The reason the bond fails with the aluminum and brass is the heat that is generated during the turning.....as to what can be done, sometimes epoxy works better than CA, and visa versa.....I feel the best way is to take very light cuts and attempt to minimize the heat. I am sure there are other replies coming that will have excellent suggestions.....
 
I think you are all on to something with the heat theory. All of my failures have occurred when I was drilling the blank for the tube and at a point when I was going into a high density wood like ebony and paduak. Thanks for your comments!
 
Jim Burr said:
Those blanks are very hard to assemble Ken...I love doing segmented pens!!!! and use both copper and aluminum. CA...IMHO is to brittle once cured. Drilling and sanding will cause "normal" epoxy to delaminate due to heat buildup. Look for a High temp epoxy, I use System 3, but I'm sure there are others out there. With these kinds of blanks it is crucial!!! to make sure the thickness of the material and your bandsaw blade match. Not so much with straight cuts, but with any curve…those must match!! If you are using CA as your finish…don't worry about "staining"…they will match in the end! If you're using anything else, shellac or WOP will work well as a barrier. Again…they are tough, but beautiful when done.
Click to expand...

Jim - where do you get the high temp epoxy System 3?
 
It can be a pain in the butt; however, if you take your time and use sharp tools it makes things a lot easier. I wrote a tutorial that may help here ( http://www.penturners.org/forum/f56/steps-i-use-scalloping-*long*-89931/ ) The missing picture on the opening page can be found on page 3 of the link.

Hope that helps

6556717125_d79709ee80_n.jpg


just have fun with it!
 
Awesome work Tim. I have to confess that it was seeing these pens on your Flickr page several weeks ago that inspired me to try it.

Ken
 
Ken,

I'm glad to hear that my work still inspires others. I can't wait to see what you come up with.
 
Ken,

If you are having trouble getting past the drilling stage, a couple of options are:

a) If you are working on a square blank, drench it in CA then glue on some wood slabs, such as tongue depressors, on each side. You can wrap tightly with twine or tape if you are obsessive - or scared. These splints will give you overlapping joint strength that will keep the blank together with cross segments. The twine will give you radial strength if you have lengthwise segments.

b) If you already have it round, just flood with CA, wrap with twine as tightly as you can and then more CA.

You still need to follow all the advice about keeping cool and sharp. My friend Hank leehljp says he may spend a day or two just drilling/cooling one blank. I just can't go that slow..:tongue: Good luck!

Harry
 
plano_harry said:
Ken,

If you are having trouble getting past the drilling stage, a couple of options are:

a) If you are working on a square blank, drench it in CA then glue on some wood slabs, such as tongue depressors, on each side. You can wrap tightly with twine or tape if you are obsessive - or scared. These splints will give you overlapping joint strength that will keep the blank together with cross segments. The twine will give you radial strength if you have lengthwise segments.

b) If you already have it round, just flood with CA, wrap with twine as tightly as you can and then more CA.

You still need to follow all the advice about keeping cool and sharp. My friend Hank leehljp says he may spend a day or two just drilling/cooling one blank. I just can't go that slow..:tongue: Good luck!

Harry
Click to expand...

Know what you mean. I was drilling one the other night, it seamed like one-eighth inch at a time - took almost four hours to drill a 2" piece; drove me crazy.
 
I emailed System 3 asking about hi temp epoxies - He replied with some interesting info - see below:

"A 5 minute epoxy will take 3-5 days to fully cure, provided that your temperatures are around 65-70 degrees. In 24 hours or less the heat deflection of the epoxy has not reached its maximum. Most 5 minute epoxies have a heat deflection of a little over 100 degrees, which means that the epoxy will start to soften at 100 degrees. Now if the epoxy is not fully cured, this softening will occur at lower temperatures.

We offer epoxies that have higher heat deflection, but they are slow setting. The T-88 and the GelMagic have heat deflection temperatures ranging from 120-140 degrees. They too take near 5 days to fully cure. You can apply heat to the epoxy (small hot box) and reduce the cure time."

Very interesting
 
I don't know that the epoxy would be enough! I've touched some of that super heated metal and it feels like it would still break the bond. Best of luck!!! Slow and steady taking shallow advances with a sharp bit. As you start to advance into the blank be sure to clear it out and soak the inside with thin CA. I go through many bottles of CA doing pens like this.
 
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