Plastic Moulding

[EricL]

Here's a quick tip that I am not sure if everyone knows about or not so I will just post and hope everyone doesnt tell me I should have known about it all along. (Whew, long sentence!) I was having trouble cutting plastic moulding with my saw. I discovered that a shot of silicon spray on the blade worked wonders. It greatly reduced the amount of melted plastic and made a cleaner cut. I respray after each frame. Anyone else have any tips for cutting this stuff cleanly?
Eric

 

[Marc Lzier]

The first is use a plastic saw blade. ( I know: bad sentence, bad sentence.)(meaning a saw blade made for cutting plastic moulding, and not a saw blade made of plastic, but that might be interesting too . . .).

Second: Have the blade pass thru the material the correct speed. The melting comes from the material rubbing on the side of the blade . A faster pass gives less rubbing. Pretty much you cut the stuff as fast as you can, if not faster. Count fingers when done.

Here is an anolgy: If you have a leaky tire you can either just keep filling it when it gets low or actually remedy the problem in a more permanent way (fix it, or buy a new one, and take those pesky nails out of the driveway).

Part of the niche plastic mldg fills is the low end. If you need to spray after each cut, the mldg is still cheap, but you take longer to cut it, and expend spray, and may addl cleanup needed (actual cost to produce goes up). If you cut it as fast possible you will be cutting it faster than wood or metal (cost to product goes down).

But if you are just cutting a few. And only once in a while; If it ain't fix, don't broke it.

But I do hope that if you are doing 8 sprays per frame you are wearing a respirator or at least a dust mask. The silicone does wonders for the lungs. Come to think of it, so does the plastic moulding. And the glue used to glue it.

BTW (by the way): What glue are you using to glue it? Regular wood glue or the super glue, melty stuff?

 

[Jim Miller]

I have the best success cutting polystyrene mouldings on the chopper. However, I can cut them on my 10" miter saw (100 tooth triple-chip blade) if I zip through the moulding very quickly -- I mean smash-cut; the quickest downward motion you can muster. What messes up the cut is friction of the blade, which makes heat, which melts the plastic. Less friction means less heat, less melting.

To join, I use cyanoacrylate (super glue) and v-nails.

I suggest avoiding silicone on the miter cuts. That might chemically react with the glue and make a weak joint.

Also, ordinary wood glue is usually polyaliphatic resin (sp?), which is best on porous surfaces. Although the plastic has holes, nooks and crannies in its surface, it isn't porous. I wouldn't use it on plastic mouldings.