Does anyone know how to adjust mechanical pressure gauges? I tried to
fix one this morning and couldn't get the pointer to rest right at the
peg. I repeatedly moved the Bourdon tube carefully until the sector ran
off the pinion in the low-pressure direction, moved the pointer about
90 degrees backward, then let the sector re-engage. The zero would land
slightly on either side of the peg. This 30PSI gauge had been
over-pressured to possibly 50, so maybe I should have readjusted it by
squeezing the bent link that connects the tube and sector gear but I
want to ask before doing this. I don't have a puller for the hand.

TIA
Jim Wilkins

wrote in message
oups.com...
Does anyone know how to adjust mechanical pressure gauges? I tried to
fix one this morning and couldn't get the pointer to rest right at the
peg. I repeatedly moved the Bourdon tube carefully until the sector ran
off the pinion in the low-pressure direction, moved the pointer about
90 degrees backward, then let the sector re-engage. The zero would land
slightly on either side of the peg. This 30PSI gauge had been
over-pressured to possibly 50, so maybe I should have readjusted it by
squeezing the bent link that connects the tube and sector gear but I
want to ask before doing this. I don't have a puller for the hand.

TIA
Jim Wilkins


A pointer puller would be a nice small machining project.

On Fri, 18 Nov 2005 18:43:15 -0500, "Jack Hayes"
wrote:


wrote in message
roups.com...
Does anyone know how to adjust mechanical pressure gauges? I tried to
fix one this morning and couldn't get the pointer to rest right at the
peg. I repeatedly moved the Bourdon tube carefully until the sector ran
off the pinion in the low-pressure direction, moved the pointer about
90 degrees backward, then let the sector re-engage. The zero would land
slightly on either side of the peg. This 30PSI gauge had been
over-pressured to possibly 50, so maybe I should have readjusted it by
squeezing the bent link that connects the tube and sector gear but I
want to ask before doing this. I don't have a puller for the hand.

TIA
Jim Wilkins


A pointer puller would be a nice small machining project.

I just made one a couple weeks ago. I used 1/2 dia brass and knurled
it. Turned down one end to about 1/4. Drilled and tapped for 10-32.
The tap drill for 10-32 is slightly larger than the largest diameter
of the needle hub. I then cut two notches in the business end. One
slot perpendicular to the puller axis and the other on the puller
axis. Used a 10-32 screw with the end turned down to just a couple
thousandts under the needle shaft dia to pull the needle. Worked great
and took all of 15 minutes to make.
ERS

wrote in message
oups.com...
Does anyone know how to adjust mechanical pressure gauges? I tried to
fix one this morning and couldn't get the pointer to rest right at the
peg. I repeatedly moved the Bourdon tube carefully until the sector ran
off the pinion in the low-pressure direction, moved the pointer about
90 degrees backward, then let the sector re-engage. The zero would land
slightly on either side of the peg. This 30PSI gauge had been
over-pressured to possibly 50, so maybe I should have readjusted it by
squeezing the bent link that connects the tube and sector gear but I
want to ask before doing this. I don't have a puller for the hand.

TIA
Jim Wilkins


I have one thing to say:
http://www.surpluscenter.com/item.as...75&catname=air

Hate to say it but an overpressure of 33% or more means that the gauge
is pretty much junk. I've had gauges go as little as 10% over and they
would not meet calibration anymore.

It won't matter where you reset the pointer as it will never read
correct pressures again. Might as well go on and bite the bullet and
get a replacement for it.

Craig C.

5.
Nov 18, 10:50 pm show options

Newsgroups: rec.crafts.metalworking
From: - Find messages by this author
Date: 18 Nov 2005 19:50:16 -0800
Local: Fri, Nov 18 2005 10:50 pm
Subject: Pressure gauge repair?
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Hate to say it but an overpressure of 33% or more means that the gauge
is pretty much junk. I've had gauges go as little as 10% over and they
would not meet calibration anymore.


It won't matter where you reset the pointer as it will never read
correct pressures again. Might as well go on and bite the bullet and
get a replacement for it.


Craig is right. I have managed to readjust gauges that have been
frozen, but even though they zero correctly, the damaged Bourdon tube
usually won't track on the calibration curve.
Bugs

In article .com,
says...

want to ask before doing this. I don't have a puller for the hand.

Really to do this correctly you need to pull the hand. There's
a zero offset and also a linear calibration. The zero offset
is handled most times by pressurizing the gage to a known
pressure and then installing the hand to read correctly. This
is typically done at half scale.

Jim


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