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Jim Wilkins[_2_] Jim Wilkins[_2_] is offline
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Default design descisions for internal tube expander

"Leon Fisk" wrote in message ...

On Fri, 18 Sep 2020 07:36:17 -0400
"Jim Wilkins" wrote:

"Jim Wilkins" wrote in message ...

"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

=====================

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.

================================================= ====
A similar idea:
http://forums.pelicanparts.com/911-9...-expander.html

Notice that he modified parts on his metal lathe. The job may not be
possible without one.


That's a nice article. Both the failures and solutions to what he was
trying to do

I'd hazard a guess that if I was to poke around in the Patent database
I'd find some interesting items that pertain to this subject. Seeing
how Charlie Brown hasn't been back to comment I don't think it's worth
my time. I'm not that interested in making such an item ;-)

Leon Fisk
Grand Rapids MI

=====================================

I am, mildly, to tighten the excessively loose fit of the slip joints in the
chain link fence top rail I use for my antenna mast. The exhaust pipe tool
might work if I can find it. Also I acquired a collapsed tube-framed tarp
garage that could be rearranged into a smaller snow blower shelter if I
could swage the tube ends to join them. I re-roofed it twice for the owner
by attaching a new tarp to PT wood strips screwed to the tubes.