Pressure gauge repair?

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

Reply to
jim.wilkins
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A pointer puller would be a nice small machining project.

Reply to
Jack Hayes

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

Reply to
Eric R Snow

I have one thing to say:

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Reply to
Tom Gardner

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.

Reply to
cvairwerks

Second that. And when you go looking on ebay, don't look for "hydraulic gauge" look for "gauge +(psi,pressure)" - waaay more hits.

GWE

Reply to
Grant Erwin
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Newsgroups: rec.crafts.metalworking From: snipped-for-privacy@tigerbyte.net - Find messages by this author Date: 18 Nov 2005 19:50:16 -0800 Local: Fri, Nov 18 2005 10:50 pm Subject: Re: Pressure gauge repair? Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse

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

Reply to
Bugs

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

Reply to
jim rozen

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