Pneumatic flow control valve problem

Can you take the knob off and stick some O rings, felt washer, rubber washer
or simlar on the shaft and then refit the knob? Maybe a stack of thin BeCu
wave washers +  flat washers?

wrote:


You're looking for a way to stiffen your knob? (allright get my mind
outa the gutter)

How about a large custom wingnut at the base. Losen wingnut, adjust,
tighten wingnut. McMaster sells several or make your own.

Karl

Tom Gardner wrote:

I'm guessing the knob has very little friction and
turns easily.

You could put a stiff compression spring under the knob to
add some friction. There may be a packing nut under the knob
that can be tightened which will also add friction.

Tom Gardner:


Tom, why not add a leaf spring with a rib that engages the straight knurl
on the knob?  That's the traditional way of keeping carburetor needle
valves from creeping.

Lloyd

Tom Gardner wrote:

Remove the knob and install a lever that the operator can just slide
back and forth to adjust?
Or maybe take the knob off, drill through the setscrew hole to create a
second hole on the other side, then install a couple nylon setscrews
that you can tighten down so it is stiffer.
Or pull the knob off and see what they use to keep the valve from
leaking through the stem, if it is set up like some are you can probably
tighten it some there.

--
Steve W.

Tom Gardner wrote:

Other folks have suggested ways to stop the knob from drifting, but I
have to ask - If the operator has to constantly adjust the speed setting
for this cylinder, could the whole mechanism use some redesign so that
intervention isn't required?

On Wed, 07 Mar 2012 02:40:18 -0500, Tom Gardner wrote:


Pid=search

If the suggestion to straight-knurl and spring-keep the knob doesn't
float your boat, how about making a splined shaft and dog clutch
arrangement, so the operator pulls the knob to disengage the clutch,
turns it, then lets go to let it settle back onto the clutch.

It's way more work than a knurl and a spring, but it's way more positive,
too.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

wrote:


Can you live with two-speed rather than variable speed? Plumb in a
parallel circuit with another adjustable valve and a quarter-turn ball
valve. With the new circuit closed, adjust for low speed. With it
open, adjust for high speed. Lock both adjustable valves in place. The
only moving part would then be the ball valve.

"Tom Gardner"  wrote in message

1. Why not re-plumb the valve to a location that does not vibrate and
possibly is more convenient to the operator?

2. check out http://www.mcmaster.com/#3408a667  Ball-Nose Spring
Plunger as a replacement set screw

A knob that is part of a threaded stem/fastener.. not enuff information.

Blue Loctite?

--
WB
.........

wrote:


Description claims there is a setscrew to lock the knob in position..
.. Simply replace the set screw with  a "friction" setscrew - one
which has a spring and a brass/nylon plug in the end of it to apply
tension.  After it has been adjusted for the proper "tension" - only a
slight change once in a while should be needed due to wear of the
nylon/brass insert.
Ken Sterling

"Ken Sterling"  wrote in message

wrote:


Description claims there is a setscrew to lock the knob in position..
.. Simply replace the set screw with  a "friction" setscrew - one
which has a spring and a brass/nylon plug in the end of it to apply
tension.  After it has been adjusted for the proper "tension" - only a
slight change once in a while should be needed due to wear of the
nylon/brass insert.
Ken Sterling
________________________________

I'll try that!  If there are enough threads it will be a good solution!