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alternative pushrod seal

Post your favorite modeling 'tips' and 'tricks'

Postby raalst » Fri Mar 03, 2006 5:10 pm

Recently I found myself needing a pushrod seal.

first, these things do not cost much at all, so
consider buying a ready made one.

But I was impatient, so I thought up a way to make one myself.

The idea is to squash an o-ring between two flat surfaces.
I used washers the same size as the o-ring.

One washer was glued against my endcap (because the
endcap itself had a rough surface and would not seal).
My endcaps are flat, by the way. This trick will not work on
Robbe endcaps.
Around this washer I drlled three holes, taking care not to
pierce the endcap.
In these holes I glued threaded rod (M3 size).

Now the o-ring can be put on the glued washer, and the
second washer on top of the o-ring. The stuff is held in place
by the rods.
Using three nuts, the upper washer is forced down.

This causes the o-ring to expand to the outside but also to
the inside, sealing off the pushrod. Be sure to sqeeze
evenly !

An alternative is to drill all the way thru the end cap
and install an o-ring at both sides.
Another possibility is to use bolts instead of threaded rod,
but I failed to tap a proper thread in one of the blind holes.
hence the glue...

Image




Edited By raalst on 1142693137
Regards,

Ronald van Aalst

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Postby Pirate » Wed Mar 29, 2006 12:39 am

Thanks Raalst. Very clever, and helpfull.

Pete
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Postby TMSmalley » Wed Mar 29, 2006 8:28 am

Good stuff Rallst!

I have seen a couple of guys use automotive rubber vacuum manifold plugs. SubRon6-er Jerome Simon uses them to good effect in his big scratch-built Akula.

Image

He buys the rubber plugs with the threaded fittings at an auto parts store (about $4 for several in a pack) takes a piece of tubing the size of his push rod (or one size smaller?)and sharpens the end. Push the tubing through the end of the rubber fitting. Viola! Instant (and cheap) push rod through hull!
Tim Smalley
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Postby raalst » Wed Mar 29, 2006 2:49 pm

Thanks for the compliments.

one note of caution : the WTC I use this seal for has not passed
its quals yet !
I tested the seal in a bucket, but the proof of the
pudding is in the sinking or something like that...
Regards,

Ronald van Aalst

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