Side view window? to see or not to see?

[cts1085]

I have been lurking on this site for a while and am beginning my build of a top hat. (5" round to rectangular port - Retired2 design with bellmouth, 32gal brute trashcan).

I have some questions on the side window:

1) How necessary is it? Are there other ways to determine how full the can is getting? how much scrubbing is going on?
2) Sources for material? (Polycarbonate at the big box stores is $$$)
3) For those that have been running them for a while - are there scratches on the inside that would change your mind now?
4) What is the minimum thickness of the plastic?

Thanks in advance for all of the great ideas!
-Tom

[Dougp28704]

I got my plastic from local mirror place. You can buy it on-line cheap. But UPS wont deliver a package that long and bendable. I went with 1/8 thick polycarbonate.

[RonS]

I use plastic Faucet handle buttons to check when the can is full, I have used these since 2008 on my Thien ShopVac unit. You can tell from 25ft away that it's full because it turns from black to sawdust color. Drill a 1" hole and glue it in from the outside with RTV.

[Peter]

Ron, that is a super cool idea.

I'm gonna steal it.  8)

[jgt1942]

Love Ron, THANKS!!!!