Just when you thought this thread was dead --
I received the hi-tech glue (PolyBond 33) from the NBond company a couple of weeks ago. This is the stuff that is formulated specifically to bond with polypropylene (like Chalkley Cups are made of) and polyethylene.
The recommended gluing process sounded complicated at first 'cuz it involved the use of a propane torch. /w3tcompact/icons/shocked.gif But it turns out to be quite simple -- you prep the plastic surface with just a few light passes out at the end of the torch flame (this has to do with oxygenation, not heat), and then a pretty good up-close blast to remove any possible parting agents or other foreign materials left over from the manufacturing process. This time the heat
does affect the plastic, making it more "willing" to bond when this glue is applied.
Interestingly, after the torching you have up to 3
days to do your gluing before the plastic settles down and has to be torched again. A complete explanation comes along with the instructions.
The glue itself is a 2-part epoxy-like goop which comes in an applicator similar to what you might be used to with other epoxy glues
plus a couple of truly nifty applicator tips that mix the 2 parts together on the fly. At first I thought this was wasteful 'cuz the tip must be discarded after each use, along with the mixed glue that's left over inside it. But when I actually started using it, I realized how nice it was to not have to worry about how much to mix ahead of time. Since it's mixed on the fly, you just just keep squirting it out until the job is finished. You use exactly as much as you need and what's left in the tip is really quite small.
Having said all that, being the clutz that I am, I put a little too much on the cup before I set the magnets in place, so the overflow practically filled that round recess where we're sticking them on. I thought it looked tacky, so I went ahead and filled it the rest of the way up. Like anybody's going to see the bottom of my cup while I'm tractorin' out in the middle of the woods. /w3tcompact/icons/crazy.gif
It's a
slooooowwwwwwww-curing glue -- firm in 24 hours, mostly cured in 48. I didn't apply any stress for 72 hours. Getting cautious in my old age.
For my field tests I spent most of 3 days bouncing my tractor around, alternating between my NBond cup and my Amazing Goop cup which had been curing for several weeks (I'm not
that patient -- it was just circumstances). At the end of the 3 days both cups were still perfectly intact. Only time will tell the real story, I guess.
One thing I
can tell you is that the pair of #41
ForceField magnets have terrific gripping strength, holding a fully-loaded 52-oz Chalkley Cup so solidly to the fender that no amount of bouncing or vibration has the slightest effect on the cup. I even accidently banged the cup with my elbow once and it didn't budge, yet lifting up on the handle effectively prys it off with little effort.
This
may be my last posting on the subject, at least until one of the glues fails. /w3tcompact/icons/smile.gif
Boring pictures attached.