by gofaster » Mon Apr 16, 2007 11:25 am
I also started my project (nearly 2 years ago) after looking at the Mercdog/MSD plans. I niavely thought I'd knock it out in a couple of weekends. These are some of the changes I made:
1. Used baltic birch plywood instead of mdf for strength.
2. increased the size of my cabinet to accomodate 12 good vacmotors
3. Added an upper plenum on top of the bench with openings on either side to force the air to change direction before reaching the orifice plate. That way the air is not blasting straight down the test cylinder at the orifice.
4. Made a stainless steel orifice plate with fixed orifices that will be closed as necessary with rubber stoppers. Made a provision on the plate to mount Bruce's sharp edge orifices. (I may end up covering all of my square edged orifices, and test only with Bruce's. I need to try both ways and see what I like)
5. Made my flow control valves out of aluminum, and used 1/2" acme rod to actuate them. I was looking at strength and longevity here, as opposed to cheap and easy. I mounted the valves in a way that takes advantage of the natural pressure differentials in the bench to aid in sealing, intake opens "out", exhaust opens "in".
6. Made hardwood gluing and screwing strips for all joints, and biscuit jointed where possible.
7. primed and painted inside the bench. I intend to use laminate on the exterior.
8. Used deckplates for all access openings and the intake and exhaust vents
Whether these changes are a recipe for success or failure has yet to be seen, as my bench is still not done yet. That's the basics. As you search and research your project, you'll find pictures and descriptions of my project and most of the other members projects generously provided in the tons of info that make up the forum. There's still an older version of the forum that is not postable anymore, but it can be searched too. (At least last time I looked). You'll see there's no "right" or "wrong" here, and there are many ingenious solutions that are shared.
I'm still working out an electro-pneumatic switching system to use an assortment of probes mounted insede the bench. If a probe seems to be in a turbulent area in a particular phase of testing, I want to be able to switch it out for one in more stable air. I may find out that some probes are in bad spots and I'll just block them out. My feeling at this time is that some spots may be more favorable for intake testing, some better for exhaust tests. If anyone thinks I'm barking up the wrong tree here, let me know.
Good luck on your new bench.
Jim