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Posted:
Tue Jan 16, 2007 9:22 amby Stef
Hi All,
Just considering vacuum motor box options and was wondering what peoples experiences were with the Audie style of motor box?
This is the type...
I was wondering if there had been any problems with sealing the rotating flow direction plate, especially with a lot of motors in the box?
Any other problems I should know about?
Stef
Posted:
Tue Jan 16, 2007 10:58 amby prschmn1
Just built a similar one here with no problems. Suggest you use Melamime covered shelving--it's the flattest and slippery. I used a piece of ABS from Mcmaster as the disc. Also curious--saw a picture of a 1600 head on one of your posts--FF racer are you?
Posted:
Tue Jan 16, 2007 11:12 amby 86rocco
It looks like Greg has. for a thread about his bench.
Posted:
Tue Jan 16, 2007 2:26 pmby Stef
Posted:
Tue Jan 16, 2007 2:31 pmby Stef
Posted:
Tue Jan 16, 2007 9:38 pmby Greg
I built mine from Audies plans. It works without any problems. I cut the disc from a piece of square plate and used the corner pieces that were left over to space the cover sheet.The disc seals well as it has no real clearance between the cover sheet and the box.
One thing I would add if I was doing it again is a flapper to cover the outlets of the motors that are not switched on, I probably do lose some air backthrough them but with 12 motors it's not really a problem. The vacuum bleed off in the photos is too big, I had to make a smaller one as it had no resolution, once it opened more than a crack, pressure dropped off very quickly and was hard to stabilise.
Also, use lots of screws and glue, I have a screw every 2" along the edges and everything is glued with PVA except the cover sheet so I can get to the motors, I used silicone on it. Also, use screw up glands where the power wires come out. The box is made from 20mm MDF, I wouldn't use chip board as it doesnt take too well to screwing into the ends of the sheets. Another hint, dont fit all the screws until you do the final assembly, I ended up having to go to a bigger screw as once it had been assemble once the screws didn't tighten up as well as they did the first time.
If you want to know anything else, feel free to ask.
Posted:
Wed Jan 17, 2007 9:30 amby Stef
Greg, thanks for all the info! It looked like you used a 3" valve in your pics for depression control? I can get a 1.5" or 2" gate valve - what size did you end up with?
I see you use 3 banks of four motors. I thought of using flapper valves, or something to prevent recirculation, not quite sure what to use yet. Has not having them not caused much of a problem because you have so many motors or is it because of the box design? I'm only planning on using six to eight motors and I don't know if less motors would make the situation worse?
Stef
Posted:
Wed Jan 17, 2007 3:01 pmby Greg
Stef,
I ended up putting a plate behind the gate valve with a 5/8 slot in it which works ok but I still mean to fit a smaller valve altogether. Most of the time I just get it fairly close to the pressure I want to test at and use the conversion in the software which is pretty much spot on. I used an electric actuator to open and close the valve which is a little too fast moving, a thread and knob to adjust it would be more accurate but at the time I wanted it all to be operated by electrics to keep it tidy.
As for the motors, I turn on more than what I need and bleed it off, it would be more efficient to use only what I need and have the outlets of the others closed off.
Posted:
Wed Jan 17, 2007 5:21 pmby Stef
Thanks again greg, you've been a great help 
Stef
Posted:
Wed Jan 17, 2007 8:14 pmby prschmn1
Only things I'd add are that I made the valve like Greg but put a piece of electrical tape at the edges where it's screwed together to eliminate some drag in it. I also split the motor box into two chambers and used toilet flaps to close one half when I want to run smaller flow rates.