Top hat design advice.

[juicegoose]

I was going to start my build this week and had a few questions.
I did search and the answers seem to be all over the place.

1. I'm getting the poly cut and not sure of the height i need to specify. I will be using a 6" inlet and outlet on a top hat design. Rectangle shoot for the inlet. I was thinking that 8" tall piece of polycarbonate will be work fine. I know it's not crucial but still

2. Where has everyone had luck finding the hvac duct piece for the outlet? Also anyone had luck at the big box stores getting poly cut? if so which one.

3. I was also thinking about putting a main 6" opening on the inlet manifold to use for most instances but also put a 4" port to use for a shop cleanup port and such. The 4" port would have a gate valve but obviously the distance from the manifold to the gate valve would be at least a couple inches. Bad idea? To much turbulance?

[retired2]

I was able to do much better at a local glass and mirror shop than the big box stores.  I could get plexi or poly cut to any size at a very reasonable price.  They cut a six inch wide x ninety six inch long piece of plexiglass for about $30. The big box stores would only sell the full sheet to get that narrow strip, and that put the price close to $100,

For the outlet pipe just buy a short length of 26ga snap-lock pipe.  Tape the joint with mastic-backed hvac duct tape.  It will never come off and it won't leak air.  You can buy snap-lock in 2ft or 5ft lengths at any plumbing/hvac supply house, and you won't pay much more, if any, than you would at a big box store, assuming they even have it.  Occassionally, I can find 26 gage at HD, but I rarely buy from them, their quality is just not as good.

[revwarguy]

I would not have the big box store cut polycarbonate even if you could get a reasonably priced piece there.  Whenever I've had anything, like dimensional lumber, or plywood cut at those places, the blades they use are so dull that the resulting tearout ruins too much of the piece.  On the other hand, I've never had a problem cutting Lexan on my table saw.  Just feed it slow, and if its thin, like an 1/8, make sure you use a featherboard to keep the material down against the table top near the blade.  Oh, and a zero clearance insert does wonders, as always.

How are you doing on your build?  Take any pics so far?

[dan4307]

Also look at local plastic and/or sign shops.  The one I found locally is more than happy to sell me off cuts from regular production at a significantly reduced price (usually by the pound).  Acrylic, PVC, poly-carbonate, etc...  They even cut it, if it is too big, for free. 

I do most of the detail cuts at home on the table saw with a carbide tipped blade or on the router.  In addition to the previous great tips on table saw cuts, if cutting thin material, make sure it can't slip under your table saw fence, which could lead to a nasty kickback.  I suspect your material will be thicker and that this will not be an issue, but worth mentioning when working with thin materials like laminates.   

I'm hoping to post some photos of my all plastic build this weekend (or maybe next week if I continue to get side tracked  :-\). 



   

[juicegoose]

Thanks for the tips guys. I was able to source some 1/8" lexan. Cost was 25 bucks for a 10"x5'x1/8"