Monday, January 7, 2013

Gluing things to Pelican cases

Pelican 1750 with mounted plate

This was a project for my dad. It is a Pelican 1750 case which has attached to it an aluminum plate water jet cut with his initials. Attaching the plate to the case was a bit more challenging than expected, and by 'a bit' I mean I spent almost 2 months worrying over it before I was willing to attempt it.
These Pelican cases are made of polypropylene a plastic which has, among its many properties, a low surface energy. Simply put it is hard to get things to stick to it.
In the past I tried a 2 part epoxy, which sticks to most things, on one of these cases and it did not adhere. Not only did it not adhere the cured resin detached from the case with almost no effort. It detached so easy I could have used the epoxy to make a mold of the case.
Eventually I checked the FAQ on the Pelican website (probably should have done this first) which recommended using 3M Scotch-Weld DP 8005. This product is somewhat pricy. I spent, before shipping, a bit more than $1/mL for this stuff. This turned out to be the least of my issues as the cartridge for the Scotch-Weld requires a special gun to apply which is sold separately.
Dispenser for Scotch-Weld Adhesives
But the gun is just the beginning of your woes. While the gun comes with two plungers (the upper black rods in the photo) neither of them works with the 8005 cartridge. A 10:1 plunger is required (the bottom rod) which also had to be ordered separately. In addition to the gun and the plunger you also need mixing tubes (the clear and red cylinders in the photo). This is the most vexing part. I assumed since the mixing tubes and cartridges are used in a 1:1 ratio and cannot be reused the mixing tube would come with the cartridge. Nope. They are sold separately as well. Maximum vexation achieved.
Mercifully after the scavenger hunt to get the parts it turned out to be easy to use with the only catch being the 8005 has a working time of only 3 minutes. The work area was protected with standard masking tape, the part to be attached was checked and aligned, the adhesive was laid down and then the part was placed and weight applied. It is necessary to support the lid from underneath. When pressure is applied to the plate the force distribution causes the case lid to bow underneath it. This would increase the gap underneath the middle of the plate if the underside of the case lid was not supported.
In the end it worked out well and the adhesive turns out to be rather strong. Hopefully I will have another project for which this 8005 will be necessary. I certainly spent enough on its accouterments so it would be nice to get more than one use from them.