Polycarbonate.

Russell

Acrylic is said to go opaque after some years of contact with cutting fluids.

Polycarbonate a.k.a. Lexan is what you want. Acrylic a.k.a. Perspex or Plexiglass does shatter, Polycarbonate doesn't.

Polycarbonate is used on industrial machines when a cheap transparent guard is required. Armoured glass is possibly more resistant to impact but more expensive.

cheers

Bill

I made some guards out of 6mm polycarbonate sheet for the museum's mills simply because it was available laying around. Slightly overkill, as 3mm would have been easier to work. The arm holding the screens is a cheap adjustable arm stand for flat screen monitors up to about 19".

Doesn’t it depend on what one is guarding against? Guarding against splashes, physical contact with moving parts, or prevention of projectiles escaping into the main workshop need different approaches.

Doesn’t it depend on what one is guarding against?

No, not really.

The OP requirement was for a clear plastic material & for a machine tool application polycarbonate sheet covers all bases, so why consider anything else ?

The only real disadvantage to it is that it scratches if you are not careful cleaning it. Some polycarbonate is available with a scratch resistant coating & industrial machines sometimes use a safety glass / polycarbonate / safety glass sandwich to give more resistance to scratching, but the downside to that solution is that an impact from a broken tool or job coming out on a lathe cracks the glass & replacements are expensive. And heavy.

Nigel B.

To bend polycarbonate, a hot air gun will do, my efforts with the 6mm were not very good, but thinner material should be easier. I tended to overheat the bend line, the picture of the guard with bent ends does not really show the poor bends. Practice with a small offcut would help a lot.