Our bench design - Our bench design

[Griffin]

[Thomas Vaught]

I just recently tested a new bench (used for intake manifold distribution checks) and was using the blow mode as the intake was used in a boosted configuration and the motors got very hot at low intake valve flows. A Lot of sparks too from one new motor so I don't know if the brushed were not aligned perfectly or I have a bad motor. I will replace the motor (115923) and see if it helps things.

How are people "breaking in" their motors if at all? Rick Blood from Flow Data says he tests
each motor for a while before installation in his benches.

Tom V.

[gofaster]

I ran each motor separately to make sure they were smooth using a rheostat out of an old appliance. After mounting them to the board, I ran them again, one at a time to make sure there was no damage or binding. Some motors arc'ed more than others at first, but they all settled down after a minute or two of running. I used the rheostat to load and unload the com/brushes, and to make sure the motors all started and ran well from low (nearly stalled) settings as well as starting with instant full current, and slid a small block of wood in front of the air inlet to mimic restrictions the motor will see in actual use. One of my main concerns was to avoid having a rotor lock after the bench is closed up.

The test showed one motor was slightly bound, due to overtightening the hold down nuts (it was repairable). At that point I decided to use wing nuts and blue loctite so the motors could only be snugged down "finger tight". The proceedure seemed to cure the problem with bound (actually just slightly tight) motors.

In industrial D.C. motors, it is common practice to put sandpaper on the commutator, smooth side facing the com, grit against the brush, and work it back and forth to seat the brush. I felt that it wasn't necessary on the little vacmotor brushes.

I also used self adhesive felt pads between the hardwood strips and the motor housings, and a heavy duty construction glue where the motors seated on the plywood base. The use of glue made the motors want to side around at first, so I took the time to make an alignment plug out of some plastic that I had lying around that the glue didn't stick to. The work took several days, as I only removed the alignment plug after the glue set sufficiently so that I couldn't move the motor.

[Griffin]

Its Finished!!!

We still have to mess with the hoses from the pitots to the FP1 a bit and troubleshoot a leak on the 3" range, but it works and works well!

Here are the final pictures:

Control valves for the pitots and static pickups



The flow ranges with the self averaging pitots and static pickups in them



The computer thats hooked to the FP1



The whole shootin match

[Griffin]

Sent the FP1 back for upgraded software and a third sensor so we can do airspeed at the same time as flow. They are also upgrading my FP3 at the same time. (They made a change to the material on the valve itself)

[dragv6]

Just a quick question is if you sit at the flow bench or stand. Looks quite low but no room for legs with a chair.

[Griffin]

[Griffin]

well - we did some more testing and I found a bunch of leaks in the test fixture - pretty much anywhere we were conting on the MDF to seal to a 2x4 the liquid nail had shrunk back causing a gap. I found some epoxy that works on wood and went to town on it last night so hopefully by tonight it will be leak free.

[Griffin]

well all the BIG leaks are gone, but we pressurized teh test fixture and tried a test John from Flow performance told me about - spray a little windex on the MDF of the settling box. sure enough it was passing a ton of air through it - we were very surprised by how much. So we need to paint the inside of the settling box now before we can continue.

The more I learn about flowbenches the more I think you ought to just build them completely out of metal and PVC pipes.

[Griffin]

FINALLY!!!! Weather station is hooked up and we flowed our first intake and exhaust port today. Intakes flowed great, but we need an improved clamping jig of some sort to keep the exhaust side buckled down and totally sealed when in blow mode. The air does seem to find ways to exit the fixture.