"Leon Fisk" wrote in message ...

On Tue, 15 Sep 2020 10:47:52 +0000 (UTC)
charliebrown wrote:

snip
I also thought about a screw-operated pair of wedges - but the
manipulation arm would have to be able to take torque as well, yet be
flexible enough to bend through the 90 degrees of the bb shell/tube
joint. A pair of wedges could be operated by cables, but again would the
advantage be sufficient given the limit of the cable.

You might want to consider hydraulics too. Like a miniature
jack/expander that could slip inside. It could have its own spring
return. Maybe design for the high pressure hose to both fit and allow
you to move it around inside the tube...

Leon Fisk
Grand Rapids MI

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Grease gun hose and copper-nickel brake line are thin, flexible tubes that
hold high pressure and connect with pipe threads. I'd start by finding a
small enough hydraulic piston seal and designing the cylinder around it.
Maybe a gas strut could be modified.