The AM Forum

What's the best readily available adhesive for plexiglas or polycarbonate? (Home Depot or Lowes)
I'm making a seethru cover for an ATU and was wondering what is the best 'glue' for this stuff.
The cyro**** stuff causes it to become milky.  Model airplane glue like they had in the 50's is no longer available.   The KISS method applies here ;-)
Thanks

Bill

If you have a hobby store in your area, or even a buzzardly hardware store, you can usually find solvent glues. The best way to go IMO. It comes in small glass bottles or in the cans like PVC cement.

http://www.rplastics.com/weldon4.html

Basically melts the Plexi to itself. Nice clear joint.

Id ask at a glass shop as they deal with plexiglass and custom work. Or go to a store and spend hours trying to read the fine print on labels >:(

Carl

Tap Plastics.

there is a solvent, available at Home Despot, I think it's xylene or toluene that should work to solvent weld acrylic panels. 

You could try this stuff - http://www.rplastics.com/weldon4.html

which a solvent based acrylic adhesive, with a retarder to slow the evaporation of the solvent to give you a bit more working time and a better joint.

The Weld-on is about the best on the market.  If you use it, keep the can of remaining glue in the refrigerator.  It has an extremely low evaporation temp but will last practically forever if kept cold.  I use a hypodermic syringe and needle to apply it (thinner than alcohol).  Best to scribe cut the plexiglas rather than sawing.

If you have trouble finding the special acrylic solvents, MEK from the hardware store works just fine. Wet sand your edges with a fine (400 grit or so) wet or dry paper.  Rinse the piece and dry the water. Fit the joint up and squirt the solvent in carefully with a syringe and needle. When the sanded joint disapears and the area looks clear, you've made a good joint. Keep it clamped until it drys.

ldb
K5WLF

I seem to recall reading that polycarbonate is a better rf insulator than is plexiglass.  I found some  charts giving the electrical characteristics at 60~ and at 1 mc, but the data all looked similar.  Polycarbonate is supposed to be much more rugged physically.

All that I can find locally is stuff made to replace glass window panes, and is only about 1/8" thick.  The 1/4" thick stuff is all plexiglass.  The thicker polycarbonate might make good open wire spreaders and feed-through insulation material if I can find some.

The roof that I put on the Dawg House was made of one of the wavy polycarbonate sheets they sell for covering decks.  I had some scrap left over, and the stuff is practically indestructible.  Bend it, stomp on it, and it springs back to its original shape with barely a dent.

I,d use hardware if possible.

Phil

Not trying to be disagreeable here, Phil, but there's a chance of stress cracks with hardware. Actually, anytime you drill a hole in acrylic and then tighten a threaded fastener through that hole.

I built an acrylic underwater camera housing using MEK for solvent welds in a plastics class in college out of  1/2" plate for the ends and 3/8" wall X 6" D tube for the barrel. Used MEK for all the joints including welding the O-ring equipped control glands to the tube and the bases for the T-bolts that dogged the back plate down to the barrel.

I took my time with the joint prep and made sure I had both surfaces well flooded, i.e. the sand marks disappeared during the weld. The housing never leaked a drop all the way down to 150' -- which was as deep as I wanted to go. I'm sure the housing would have handled a much greater pressure.

ldb
K5WLF

Probably what would work with the hardware is what I use with ceramic insulators. I picked up a  roll of cork sheet that is made to line the bottoms of kitchen drawers.  I cut gaskets out of it to go under the washers, and that seems to take enough of the stress out of the uneven spots to prevent fracturing the ceramic.  I think that is what happens with the plexiglass too.  The cork acts to pad the rigid metal from the brittle ceramic or plastic.  Most ceramic hardware manufactured for radio use originally came with a set of cork gaskets from the factory.

The sheet of cork I use is about 1/16" thick, and comes with an adhesive one one side, backed with some kind of slick paper. After cutting out the gasket, you peel off the paper and the cork adheres to the hardware or to the ceramic or plastic as you choose.  The sheet cost about $8 from Lowe's, and would probably last most people a lifetime even if they built lots of projects.