New here - a couple questions - New here - a couple questions

[Griffin]

Howdy!

First off awsome forum - found it a few days ago and have been poking around doing some searching and reading old threads since then. There is a TON of information on here and its taking a while to digest it all.

My name is Dave - I am getting ready to build a flowbench in conjunction with a friend (we are shooting for around 800 CFM)

Anyways I was just hoping you all might have some suggestions of old threads I could look for that I may have missed that have good information for when you are getting started?

I also have a couple specific questions.

1 - I've noticed a lot of folks use particle board, but a lot of other folks suggest plywood. I don't mind spending the extra money on nice plywood, but are there any issues with leakage or anything of the sort when using plywood?

2 - We were thinking 4" PVC for our piping, should that be suffucient for 800 CFM?

3 - I stumbled across a Depression controller from Audie that looks pretty dang cool - do you guys think 90 amps would get the job done for 800 CFM? Also are there any issues with regards to loss of ability to measure small pressure fluctuations and whatnot when using one of those?

4 - Do you guys have any reccomendations with regards to the computer measurement systems offered by Audie and Performance Trends? Is one superior to the other?

5 - for treating the inside of the plenum and vacuum boxes - is using paint and sealer best, or is using drywalling compound or joint compuund for flooring or something better?

Thanks in advance for your help! I'm sure I'll have a ton more questions before I'm done.

[bruce]

[Griffin]

[Tony]

[Griffin]

so a double layer with a sheet of 3/4" MDF on the inside and a good quality 3/4" plywood on the outside with the interior painted with a good marine varnish would probably be the ticket? Is there a rule of thumb for the spacing of support struts inside the vacuum chambers?

[Tony]

No strict rules here, it just requires sufficient mechanical strength.

The traditional way is to glue and screw the panels using all timber construction. That would be fine, except some future access will always be required for maintenance. Wood screws never go back quite as tight as the first time. After removing and replacing those same screws in those same holes maybe ten times, you may be getting in deep trouble....

In my humble opinion, a much better form of construction is a welded steel frame, with panels bolted onto the outside. I fabricated my own frame from scratch, but others here have adapted an existing heavy steel frame salvaged from somewhere. In retrospect that is undoubtedly a much smarter way to go about it. You may be able to find, for example, a piece of old electrical equipment at a machinery junk yard built into a suitable heavy frame.

I used one inch MDF for all my panels, but three quarter MDF would probably be o/k. The edges are easier to work with, and look better than marine ply. What you can get away with, mostly depends on maximum attainable zero flow air pressure, and exposed panel area. I used a router bit to round all my external edges and corners after all the panels were finally bolted in position. If the panels are glued or gasketed to a welded steel frame, it simply is not going to leak, especially at the corners. Gasketed access panels using studs and external nuts, can be removed in less than a minute with a rattle gun, and go back just as fast with guaranteed zero leakage. Wood screws are an absolute curse !!

[Griffin]

Great info and great ideas! I'll definitely start looking arond for some old unused steel frames or at least some old steel. (I have a couple welders so a frame is not a huge deal)

Bolted access panels is also an awsome idea - definitely going to do that!

When you guys make you gaskets, so you just paint the board, spray with silicone lube, and use silicone caulk on the other mating edge all the way around like I saw reccomended for making gaskets for salad bowl based flow valves?