Gluing Coke Can Laminations Into Segmented Blanks

[Randy_]

Some time ago there was a thread...probably more than one...asking about the best glue to use when laminating pieces of Coke can into segmented pen blanks. The question was asked because someone had a blank come apart at a CC lamination and the type of glue was suspect.

As you might expect every glue had its proponents and a few were so bold as to suggest that glue type had nothing to do with the problem and that folks should be looking to the surface prep of the laminates and material conditions such as using particularly oily woods.

I decided a few tests of various types of glue might be in order to see if I could detect differences in the strength of a standard glue joint. The test was to be fairly simple. Cut some Coke cans into 1" wide strips, glue them together with only a 1" overlap and after the glue was dry, pull the joint apart while measuring the force required to destroy the joint.

Well, I got distracted from the experiment and it sat on the back of the workbench for a while. Several days ago I had my tubes of JB Weld out for a bicycle repair and decided to mix up a little extra and glue a couple of pieces of Coke can together. Now JB Weld is not the glue of choice of most segmented pen crafters; but it is really nothing more than a semi-specialized epoxy glue so I figured it would make an interesting data point for my little project.

I haven't worked out all of the details of measuring the force required to destroy the joint, yet, so the first test didn't prove too much. The joint did successfully support my 45 lb. tool box. I then decided to see if it would support me at about 5x the weight of the tool box. At this point the test failed. With an estimated 100 lbs. applied to the glued joint, it held just fine; but the metal strip of Coke can, itself, failed. I think the clamp that I was using to grip the metal strip damaged the strip and caused it to fail.

Guess I will have to redesign the test a little; but am looking forward to finding out if the glue is the issue here or if some other factors need to be addressed in using metallic layers in segmented pens.

 

[PaulDoug]

I'm anxious to read the results of the test. Seems like 200+ pounds is a little more than a pen blank would need to hold.

 

[GaryMGg]

Randy,
This sentence makes me think you're testing the can-to-can glue joint strength:
"Cut some Coke cans into 1" wide strips, glue them together with only a 1" overlap and after the glue was dry, pull the joint apart while measuring the force required to destroy the joint."
I'd expect most glue-joint failures would occur between the can and wood or can and acrylic.
Did I misunderstand what you're testing?
If not, do you plan to can to wood and can to acrylic?

Thx,
G

 

[Rudy Vey]

I am not quite sure, but I believe these cans are painted on both sides, inside and definitely on the out side. The test should be repeated with the two sides sanded down to the bare metal. This would exclude influence of the paint. Certain glues my weaken the paint adhesion due to attack on the paint layer (which is very thin), and, therefore, fail.

 

[mikemac]

You're testing "glue strength", because I"m assuming you've experienced blanks coming apart on you at some point.

I have laminated coke can segments before, and definitely experienced them coming part, and for me, was ALWAYS during drilling. Because I was using brad point bits, when I drilled thru the metal, it would cut a small metal disc and that would stay on the bottom of the bit/flutes, and after that, any further pressure wasn't drilling thru, but PUSHING the blank apart from the inside.

My solution was simple to stop after each piece of metal, and clear the drill bit. After that, no more problems.

My glue method was simply roughed up coke can, and CA.

I guess its important to also know HOW you're testing these joints.. if you're testing shear, i would wonder why? My personal opinion (worth exactly what you paid for it ) if the joint in a pen is failing due to SHEAR, just how are you (or the owner) treating the pen?

Hope this helps.

 

[mikemac]

One more note.. cans are coated on inside and outside.. inside has a protective lacquer.

 

[Randy_]

Originally posted by PaulDoug

I'm anxious to read the results of the test. Seems like 200+ pounds is a little more than a pen blank would need to hold.

Paul: I don't really have any idea how much joint strength a joint needs to develop to be adequately strong for a successful segmented pen. Could be 50 lbs. or 100 lbs. or 500 lbs.?? What I am more interested in than absolute values is to discover if there are some glues that provide significantly more or less joint strength than the others.

One thing you have to remember is a little HS geometry. In my test, the glue joint is approximately 1 square inch in area. If you use a 3/4" ± blank to make a pen that will be about 1/2" in final diameter. The glue joint will only be about 0.056 square inch in area. And more critically, during the drilling process, once your drill bit has penetrated the CC lamination the area of the glue joint shrinks to about 0.44 square inches or about 20%.

(Note: The above numbers assume the glue joint is perpendicular to the long axis of the pen blank. If the glue joint is at some smaller angle to the pen axis, the area of the glue joint will increase. But if the CC lamination is at some angle other than 90° to the long axis of the pen, it will be presented to the drill bit at that same angle during the drilling process and there will be some unbalanced forces created that do not exist when the lamination is perpendicular to the drill bit. Whether this could affect a blank staying together or not is well beyond the scope om my little experiment.)

 

[Randy_]

Originally posted by GaryMGg

Randy,
This sentence makes me think you're testing the can-to-can glue joint strength.....Did I misunderstand what you're testing? If not, do you plan to can to wood and can to acrylic.....

Gary: You are correct. I am testing a metal to metal joint.

My reading of the previous comments on this subject seem to suggest, rightly or wrongly, that most folks are concerned with how well the glue bonds to the metal, so that is what I am looking at. I think everyone is satisfied that the any of the glues will bond adequately to the wood.

You may very well be correct that a wood/metal joint behaves differently than a metal/metal joint. My initial intent was to do a few quick and dirty tests to see if anything of interest developed. I am always open to suggestions that would improve my testing technique or ideas for additional tests that might shed more light on the subject.

Thanks for your comments.

 

[Randy_]

Originally posted by Rudy Vey

I am not quite sure, but I believe these cans are painted on both sides, inside and definitely on the out side. The test should be repeated with the two sides sanded down to the bare metal. This would exclude influence of the paint. Certain glues my weaken the paint adhesion due to attack on the paint layer (which is very thin), and, therefore, fail.

Rudy: You are correct. I have seen that coating described as being made of several different materials and I'm not confident that any of us really know exactly what it is. And, of course, it is quite possible that outer coating is different than what is on the inside.

Regardless, I agree with you that anyone who tries to glue up a Coke can lamination without thoroughly removing said coating by sanding is making a "BIG" mistake. In the first glue test that I performed, I was careful to be sure the all of the coating was completely removed. Just for fun, however, I do intend to try some glue joints on strips where the coating has not been removed to see how much, if any, difference it makes.

 

[redfishsc]

How about this for a test of the wood-metal-wood joint strength:


2 scraps of wood, say 3" wide by 3" long by 3/4" thick. Edge-glue them together, long grain with long grain, with the soda can sliver in between--- to make a new piece that's 3" wide by 6" long.

Clamp and cure overnight to allow all the glues to reach a workable cure...


Clamp one side of the newly created 3X6" piece to the table, with the soda can joint sitting just beyond the edge of the table (parallel to the edge of the table). Hang a weight off the other side of the joint on the other piece of wood---- see which glue holds the most weight.


Someone is bound to say "sounds like a good idea, redfish, why don't you go try that?"

Well, two reasons. 1) I'm lazy 2) I'm taking a summer class that has me wiped out on time and 3) I'm sure someone here who loves to experiment will come up with a much more accurate way of testing this.

 

[Randy_]

1

Originally posted by mikemac

You're testing "glue strength", because I"m assuming you've experienced blanks coming apart on you at some point.....ALWAYS during drilling. Because I was using brad point bits, when I drilled thru the metal, it would cut a small metal disc.....after that, any further pressure wasn't drilling thru, but PUSHING the blank apart from the inside.....I guess its important to also know HOW you're testing these joints.. if you're testing shear, i would wonder why.....

1. Never made a segmented pen. I'm just curious to learn what I can about how well different glues adhere to Coke can material.

2. I understand what you are saying about creating little disks when drilling with a brad point bit and it makes perfect sense to me. Of course, many folks do not use brad point bits so there are others factors at play. The other point worth making here is that the disk thing is only true if the CC lamination is perpendicular (or nearly so) to the drill bit. If the laminations are at an angle to the drill bit, like they would be if one were making a Celtic knot or some similar design, a disk would not be formed although clearing the bit on a regular basis would still be prudent.

3. I'm not an engineer...just a shade=tree pencrafter <<GRIN>> so I may not be using the correct terminology; but, yes, I think I am testing sheer strength. And I could be wrong about this; but it seems to me that sheer is one of the primary forces involved with the drilling process.

 

[Randy_]

Originally posted by Randy_

1

Originally posted by mikemac

You're testing "glue strength", because I"m assuming you've experienced blanks coming apart on you at some point.....ALWAYS during drilling. Because I was using brad point bits, when I drilled thru the metal, it would cut a small metal disc.....after that, any further pressure wasn't drilling thru, but PUSHING the blank apart from the inside.....I guess its important to also know HOW you're testing these joints.. if you're testing shear, i would wonder why.....

Mike:

1. Never made a segmented pen. I'm just curious to learn what I can about how well different glues adhere to Coke can material.

2. I understand what you are saying about creating little disks when drilling with a brad point bit and it makes perfect sense to me. Of course, many folks do not use brad point bits so there are others factors at play. The other point worth making here is that the disk thing is only true if the CC lamination is perpendicular (or nearly so) to the drill bit. If the laminations are at an angle to the drill bit, like they would be if one were making a Celtic knot or some similar design, a disk would not be formed although clearing the bit on a regular basis would still be prudent.

3. I'm not an engineer...just a shade=tree pencrafter <<GRIN>> so I may not be using the correct terminology; but, yes, I think I am testing sheer strength. And I could be wrong about this; but it seems to me that sheer is one of the primary forces involved with the drilling process.

 

[Randy_]

Originally posted by redfishsc

How about this for a test of the wood-metal-wood joint strength:

Matt: That would certainly work; but I don't think that would test the type of joint strength I want to look at. Your test would test the tensile strength (think) of the glue joint rather than the sheer strength.

By way of explanation, using the glue-up you suggested, to test the property I am interested in, one end of the glue-up would need to be put in a vise and the other end grasp with a pipe wrench or some similar tool. Then the upper end of the glue-up would need to be rotated/twisted around the long axis of the glue-up.

Does that make sense??

 

[redfishsc]

Yes, you are wanting to torque the joint (man does that sound woodstock-hippy or what?).

If you have a way of connecting a torque wrench to the deal, you could measure how much torque it took, but if I were using a standard torque wrench, I'd use a much smaller piece, such as two 1X1" blocks glued together. I have a feeling 3X3" blocks glued together would out-muscle a standard torque wrench.

 

[JohnU]

I use CA on my metal to wood and dont have a problem. But... Im not using pop cans so maybe that makes a difference. Not sure about your local newpaper but mine runs an add in the paper every week selling their aluminum sheets used in the printing process, for $.50 each (about 18"x32") and theyre flat and easy to cut. I bought six last year and still have 5. Some come with ink on them but I wipe then off with acetone and scrub them with sandpaper upon gluing, even though the ink doesnt all come off, they work just fine. It might be worth check your local paper printers.

 

[redfishsc]

What a great idea John, I'll have to keep my eyes open for that!

 

[altaciii]

john, how thick are the sheets?

 

[Brandon25]

I know I'm late on this, but I would also add that resistance to force may not be the only factor in play here. I've heard that CA breaks down at 165 degrees, which is easy to reach when drilling if you aren't careful, I'd think.