Author Topic: Boiler Gauge Glass  (Read 645 times)

Offline Robert Hornby

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Boiler Gauge Glass
« on: May 03, 2019, 12:09:30 AM »
I have managed to break the gauge glass on my launch boiler. I have trouble in making them to the correct length as often they break whilst trying to cut them. I have used my cutoff disc on my angle grinder to get close to the correct length then try to bring it down to size. So any ideas how I can prevent the breaking?
Robert
Age and treachery will always overcome youth and skill

Offline derekwarner

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Re: Boiler Gauge Glass
« Reply #1 on: May 03, 2019, 12:37:54 AM »
Robert...there are 100's of reports on methods

a circle of cotton twine soaked in meths....light then light,  bend/snap  :Mad:
a nick with a 3 square [triangular] file ......then bend/snap  :killcomputer:

The mini grinder was from JayCar.......don't be tempted in using their reinforced cutting discs .....but get a 6 pack of 20 mm diameter diamond dusted cutting discs....[cheap as chips] $10.00 for 6 discs + 2 arbors including postage to OZ]

The diamond dust coated disc will slice through the toughened glass capiliary tube like butter ...cut off to length.....do not attempt to polish.....wave each end of the capiliary tube over a gas flame until the end of the glass tube is red.....[then air cool]...this actually fluidises the glass and the sharp edge with cutting marks are gone!

The finished end and face surface will be absolutely suitable for an O-ring to be compressed against

I also use the same diamond dusted cutting discs for cutting K&S brass telescopic tubing

Derek
« Last Edit: May 03, 2019, 12:46:29 AM by derekwarner_decoy »
Derek Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline Robert Hornby

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Re: Boiler Gauge Glass
« Reply #2 on: May 03, 2019, 12:18:28 PM »
Thanks Derek, Lots of things for me to try.
Robert
Age and treachery will always overcome youth and skill

Offline Ye-Ole Steam Dude

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Re: Boiler Gauge Glass
« Reply #3 on: May 03, 2019, 02:01:05 PM »
Hello Robert,

I second what Derek has stated;

The diamond dust coated disc will slice through the toughened glass capiliary tube like butter ...cut off to length.....do not attempt to polish.....wave each end of the capiliary tube over a gas flame until the end of the glass tube is red.....[then air cool]...this actually fluidises the glass and the sharp edge with cutting marks are gone!

I have had 100% success with this method.

Have a great day,
Thomas

Offline Steamer5

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Re: Boiler Gauge Glass
« Reply #4 on: May 04, 2019, 02:34:48 AM »
Hi Robert,
 Back in my lab training days using Pyrex glass, it was a nice sharp triangular file, one stroke using the corner, split on the finger & apply to the cut ( all hi tech stuff! ) then WRAP in a cloth with the nick pointed AWAY from you thumbs together push & it snaps on the nick. Then fire polish the ends.

Like Derek said there are lots of ways, the above Iíve used on tube from 3 or 4 mm to 12 to 15mm, the diamond disc sounds stress free!

Cheers Kerrin
Get excited and make something!

Offline steamboatmodel

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Re: Boiler Gauge Glass
« Reply #5 on: May 04, 2019, 03:09:24 PM »
When you flame the ends of the tubes be careful until it is completely cool. The glass retains the heat for a long time and if you pick up the wrong end you can get a bad burn.
Gerald.
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long