Valve mterial?

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pezman
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Valve mterial?

Post by pezman » Wed Dec 29, 2004 6:58 pm

I had an old tape measure fail recently and as it's guts spilled out, I realized that the spring inside is thin spring steel (of the blue variety). I think that you could fabricate some small v-valves or maybe a "U" valve (i.e. a 1" wide strip of steel covering two slots and held in place by a pin, like so:
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dynajetjerry
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Re: Valve mterial?

Post by dynajetjerry » Thu Feb 10, 2005 3:42 pm

Hi, Guys,
On the subject of using a strip of material from an old steel tape measure, I would be very surprised if that is feasible. The force needed to flex it enough to allow air passage appears to be much too great. However, it is conceivable that slitting it part way across so that there are many narrow reeds may be possible. The seat would need to be curved to closely match the shape of the steel strip when it is unflexed. Otherwise, severe leakage could take place.
dynajetjerry

pezman
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Re: Valve mterial?

Post by pezman » Thu Feb 10, 2005 4:12 pm

Actually, a piece of pipe would be about the right diameter to match the curve of the steel. Maybe a pipe sticking into the CC with slits in it, and the pieces of steel covering the slits.

The main point of the post was mostly to point out an inexpensive source of blue steel that folks might not be aware of.

BTW the steel that comprises the spring inside the tape seems to be considerable thinner than the tape itself.

larry cottrill
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Re: Valve mterial?

Post by larry cottrill » Thu Feb 10, 2005 4:14 pm

dynajetjerry wrote:Hi, Guys,
On the subject of using a strip of material from an old steel tape measure, I would be very surprised if that is feasible. The force needed to flex it enough to allow air passage appears to be much too great. However, it is conceivable that slitting it part way across so that there are many narrow reeds may be possible. The seat would need to be curved to closely match the shape of the steel strip when it is unflexed. Otherwise, severe leakage could take place.
Jerry -

I'm glad you brought this up. The solution is to seize the tape so it is flattened where it's held, then allow it to "roll out" flat along the retainer. Try it - hold a steel tape in your fingers and gradually try to bend it - at first, it's very difficult until it flattens and bends; after that, additional bending is very easy - a fraction of the force needed to get it started!

Here's my old design to try to do that. The seat surfaces have to be carefully filed for a good seat on the tape, which has a varying degree of curvature along its length. Nothing is easy ...

L Cottrill
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Steel Tape Engine.jpg
Steel measuring tape engine valve. Copyright 2002 Larry Cottrill
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