v nails for polystyrene?


CGF, Certified Grumble Framer
Jul 24, 2004
Round Pond, ME
I need to make 70 large frames using an extruded polystyrene moulding. What type of v nails should I use? Thanks for all inputs.
"Soft wood" variety. They are sharper and have a shallower bevel.

EDIT: The v-nails in polystyrene are really only acting as internal clamps until the solvent/glue dries. I have never seen a properly glued polystyrene frame break at the joint regardless of the kind of mechanical fastener.
I agree with Wally. And here's one more bit of information:

Poly mouldings are dense, something like MDF (no reference to hardness here). When the v-nails go into the material, it does not compress as wood does. So, each v-nail acts like a wedge, and too many v-nails could cause a separation at the outside of the corner. One way around this is to glue & vice the corner, then let it dry before v-nailing. If that's not practical, then be cautious about placement, and using too many v-nails.
What type of glue do you use?

I've been using cyanoacrylate and holding the joint together by hand for 15 seconds, then inserting vee nails after the frame is together.

You're right that the joint never breaks. I have tried to break a few and they always break somewhere near, but never on the joint.