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So for my third pen (I’m new to turning), I wanted to attempt the celtic knot. I used a light colored wood for the blank (cypress), and walnut for the knot - outlined in aluminum foil. I glued alum foil on both sides of the walnut using CA glue, the Gorilla Glue brand. I did the same when gluing the pieces into my pen blank.

Problem came when drilling the blank. The piece cracked and came apart at the aluminum foil.

Question I have is, would epoxy be a better choice here? Or wood glue? Anybody have success with this?

I can upload pictures later when get home. Thanks in advance!
 

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As you observed, the CA glue does not bond well with the smooth surface of aluminium foil.

Wood glue normally pops off metal.

Your best choice would be 2 part epoxy. I would also wipe the foil with acetone to remove any potential film of oil/grease e.g., from your skin.

I would do a test piece first of just a piece of foil and e.g., the walnut. Let the epoxy harden and then see if the foil can be removed. If so, then you need to consider either another brand of epoxy, or roughing the surface slightly with sand paper to improve adhesion.
 

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It will always be a weak point no matter which glue you use, since you're attempting to glue shiny metal to the end grain of wood.

I suggest you add splints glued length-wise along all four sides of the blank, do all four sides to keep the drill centered (which is important to keep the knot symmetrical).
 

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Like stated, your going to have problems drilling regardless of the glue used. These can even be the case without the aluminum. The splints are a good idea. I have also just taped the entire blank up for drilling, that seems to hold everything together. Once you get the tube epoxied in, your usually good to go.
 

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BassBlaster, you use epoxy for the tubes as well? I've been roughing up the tube with 80 grit sandpaper then applying CA glue on that as well.

Have you had bad experiences with that?
 

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I havnt had a bad experience with CA but I have never used CA for glueing tubes. I have always used epoxy. Ive read of many failures with CA but never a failure with epoxy and thats why I use epoxy only. I figure since I turn pens to sell, its in my best interest to take every precaution I can to make sure the pen dosnt come apart down the road. Besides, epoxy is a whole lot cheaper than CA and really dosnt take any more time. I use the Loctite 5 min epoxy and I can turn a pen 15 minutes after the glue up. In my shop, CA is a finish!!:thumbsup:
 

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Well you had 3 weak points. CA glue is brittle especially on end grain. End grain joints themselves are a problem. Aluminum foil simply isn't strong enough to hold anything.
First you need something with some strength. Aluminum, copper, brass and Pewter will all turn well on the lathe. You can find brass shim stock in the magazines and sometimes you can find some thin copper or aluminum flashing at the hardware. Scratch them or sand them with course paper to give some tooth for the epoxy.
Epoxy or Polyeurethane glue are both good for gluing metal to wood however in my tests the epoxy holds fare better when gluing end grain to end grain.
On pen blanks it's hard to avoid end grain glue ups on the celtic knot. The brass tube of the pen is what holds it together so the problem is drilling. The ideal way is to have 2 V blocks holding the wood so it can't explode on you. I do this with wooden blocks in my vise. Then drill slowly removing the bit frequently because heat will also cause any of the glues to give up the ghost.
 

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I do abit of segmenting so I will post a couple suggestions and these are purely my own opinions so do with it as you may. First why aluminum foil??? This is way too thin. You will not get the effect you are after in my opinion. I would use sheet aluminum such as flashing which you can get in the roofing section of Home Depot. Makes for a better effect. Next I too always use epoxy when working with metals and woods or acrylics. I will use CA with acrylics and wood. I always epoxy my tubes. Remember that is also what is giving those joints support in the long run.

When going to turn I would knock those corners off. I usually round my corners on a belt sander. Takes a couple seconds. Then douce the entire knot with thin CA. You can continue to do this as you turn down the blank. Turn the lathe off if doing this and protect the lathe bed. Don't ask!!!!

Do not be in a hurry to drill after glued. Let the glue cure. Good luck and look forward to seeing what you got.

Hey John Lucas, I like your thinking. I was typing while you were posting.
 

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Discussion Starter #11
Great tips. I had no idea.


Foil because a thought a fine metal line would look good. It kind of worked on a different sample, but your right it's hard to see

image-3762101347.jpg
 

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Not bad but as you see you can not even see the aluminum. I also see you use 45 degrees for your cuts. Maybe you would like to try 60 degrees and stretch out the cuts more.







 

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JTTHECLOCKMAN - Nice work, its so...perfect haha. How thin is your saw blade by the way, or are you using the bandsaw for your cuts? My lines seem so FAT compared to yours. I also like the idea of a 55-60 degree cut in lieu of 45.
 

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JTTHECLOCKMAN - Nice work, its so...perfect haha. How thin is your saw blade by the way, or are you using the bandsaw for your cuts? My lines seem so FAT compared to yours. I also like the idea of a 55-60 degree cut in lieu of 45.
Just a standard thin kerf blade 3/32"

Doing 60 degrees will stretch out the design and enlongate it. The key to a good knot is that the pieces are the same size opposite each other. Then you know you used the right material and the glue joints were spot on. Make sure your fill in material is the same thickness as your blade that you cut with. A bandsaw to me is too thin but some people go for that look too. Good luck
 
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