View Full Version : UHMW Plastic - Can it be Glued?
06-22-2002, 06:31 PM
I've a custom blade to rip a groove to accept cedar wedges. I would like to attach a wedge of UHMW plastic aft of the blade to the base of my circular saw to act as a guide. Textbook says to use a batten to guide the saw. However, it would have to be a pretty thick batten in places do to the curvature of the hull.
It will be close work to drill and fasten with screws. I was hoping glue might be another means of attachment. I know the stuff is slippery (that's why I bought it). I guess as an alternative I could use a piece of hardwood and wax it. Any thoughts?
06-23-2002, 12:03 AM
I think that your only real chance of finding an adhesive for the plastic is to contact the technical rep of the company which made the plastic. Frankly, I don't think your chances of success are worth waiting on. I would recommend that you look into using hardware fasteners to secure the plastic to a wooden backing plate.
06-23-2002, 01:05 AM
You could try a test with some scrap. Rough it up well (about 60 grit) on the bonding surface of the plastic, clean the piece with acetone, let it all evaporate off then get out your handy propane torch. Light the torch and quickly run the flame (the blue part) over the bonding surface of the plastic. Do it fast, as you're not trying to heat or melt it, just to drive out the evil spirits (or something equally strange that we would need The Chemist to explain - trust me, it's important - has to do with polarizing the little bits on the surface to get a good bond). Apply epoxy, clamp it, let it cure and then beat on it to see how strong the bond is. That's essentially how we used to glue UHMW when repairing ski bottoms. The epoxy that we used was very rubbery, slow to cure and flexible, but you could try any type and see what kind of results you get. I suppose it might also be possible to use wood for the bolt-on structural pieces and face them with a thin layer of glued-on UHMW to make them slick. The glue bond would probably get less stress. You could also face the wood with Formica if UHMW won't stick.
There is a company that makes two-part (probably epoxy) adhesives for slick plastics at:
their technical info sections for their PB-33 glue are pretty interesting.
06-23-2002, 08:31 AM
The only glue I have seen stick to polyethylene or polypropylene plastics is hot melt glue. That is probably because a lot of hot melt glues are low molecular weight PEs. A couple of days ago a neighbor broke his rain gauge mounting plate trying to center punch it to drill it. He was going to try epoxy. I told him it wouldn't work, but to bring it over to my shop and try hot melt glue. He laid a small bead on the broken edges, pressed them together tightly, and in less than a minute tried unsuccessfully to break the joint.
You could try Loctite 406. I have used it to bond all manner of difficult plastics.
06-23-2002, 03:08 PM
Flame or intense ultraviolet exposure breaks/burns off hydrogens attached to the carbon atoms, creating molecular fragments and free radicals. Whilst fresh, epoxies bond nicely to them, and thus to the surface.
Basically no, you might get it to stick for a little awhile with hot melt glue or the stuff you re-attach rear view mirrors to your windshield with. It will fail exactly when you don't want it to. If you're using this stuff for a jig or fixture on or with a saw that means an accident of some sort. Check out using some nylon instead, it's available in sheets and shapes, it's alot cheaper than UHMW and it's easier to bond/glue. Good luck.
06-24-2002, 06:33 AM
Geo: You're sure the're talking about a batten in the kerf ? I've tried it with a router, didn't have a lot of luck. It sounds like you've got a lot of slots to cut, but battens parallel to the cut, at the edge of the base, would be my choice. Maybe you could use a brass pin or pins. They would be easire to fasten, and give you the same guiding action.
06-26-2002, 01:34 PM
I used the stuff on the bottom of my dog sled runners and checked the possibility of glueing. Plastic company says nothing will stick to it for long. I guess your stuck with mechanical fasteners. :(
06-26-2002, 02:56 PM
Geo, just one thought, You might try drilling and attaching pins in the UHMW strip and then drilling holes in the saw plate to accept them. You can tap UHMW at least with a course thread. Good luck...Gary
06-26-2002, 03:38 PM
So. To summarize: You can. You can't.
06-30-2002, 12:29 AM
Thanks guys. As it turned out, a 3/8" X 1/2" batten tacked along the seam worked fine. Curvature was not so that it failed to keep the saw on track. The job should be done tomorrow. The custom blade and Makita worked slick. I've nice neat grooves to accept the wedges. Will post pictures later. CIAO :D
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