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Posted:
Mon Feb 26, 2007 10:15 am
by gofaster
Erik,
I started to use Delrin, but was concerned about stripping the threads. Delrin and aluminum cost nearly the same, and I felt more comfortable trusting the aluminum. I liked Delrin because there was no fear of corrosion. I treated the threads of the steel and aluminum parts with a dry graphite lubricant. It is applied with a brush, and dries like paint.
Posted:
Mon Feb 26, 2007 9:37 pm
by Thomas Vaught
I used "half-moon" shaped parts similar to the "bowls" used in the old
MSD articles but made the valves out of aluminum, very rigid!
The valves have a sealing flange that is 1/2" larger in diameter than
the "bowl" diameter.
I made the valves with a helicoil insert that was loctited in place so when the threaded rod is turned the valve will move. To keep the valves in one position (so they don't turn) I added a tab on the flat side of the valve with a smooth rod some distance away from the valve edge. This
smooth rod moved inside a close tolerance hole in the valve sealing partition. No leaks past the rod but the valve can move open or closed and remain in a basic position (like say 3:00 on a clock face) as the valve moves in and out in the flow hole.
This allowed me to also be able to make flow adjustments without the flow knobs getting higher or lower on the bench face.
Tom V.
Posted:
Tue Feb 27, 2007 12:18 pm
by gofaster
Here are more pictures of the motor board, the valve assembly, and the orifice plate.
The motors are Ametek 115923's. They are glued to the board with construction adhesive and located by oak slats with felt pads, and I used wing nuts so I wouldn't overtighten and crush the fan housings. They are kinda fragile. I used a router to radius the entries. The plate holding the wiring cordgrips is supported by a board that mimics the placement of the plate on the bench. The plate is stainless steel.
On the back of the valves there's a 3/8" rod that is parallel to the threaded rod which keeps the valves from turning. The valves are opposed. That will let depression help seal the intake when exhaust testing, and pressure in the cabinet will help seal the exhaust valve when testing in intake mode.
The orifice plate is stainless steel with "square edged" orifices. It will use rubber stoppers per Thomas Vaught's suggestion. The largest opening has four thumbscrews surrounding it. This is so I can try using some of Bruce's orifice plates over this opening to compare results with my openings. If I like the results/repeatability with Bruce's plates better than my own it leaves me the option to switch without having to tear the bench apart.
My thanks again to flh1960 for hosting the pictures for me!
Posted:
Tue Feb 27, 2007 3:04 pm
by larrycavan
Posted:
Thu Mar 01, 2007 2:13 pm
by Erik
Jim
My threaded rod dont rotate it is fixed in the delrin pice the nut for the thread sits inside a pipe that rotates and are fixed to the front panel so this allowed me to also be able to make flow adjustments without the flow knobs moving. I also have a rod and a giude on the face of the delrin pice so it dont rotate.
My finale pictures
Posted:
Thu Mar 01, 2007 8:39 pm
by larrycavan
Nice Eric.
Posted:
Thu Mar 01, 2007 9:38 pm
by bruce
Yup nice bench!
Posted:
Thu Mar 01, 2007 9:47 pm
by Thomas Vaught
You can wire any of my benches any time you want. Nice work.
Tom V.
Posted:
Wed Nov 19, 2008 8:45 pm
by blaktopr
From looking at all these benches on this site, I have to say mine has to be the ugliest bench in existence. Looking good dude.