Ideas on how to re-connect a broken thread in an alcohol thermometer

[GreensandsParticipant @greensands]

I have a 0-50deg alcohol thread thermometer sold for use in aquariums which I have been using as an outdoors thermometer. Problem is that despite being in a fixed location mounted on a shed wall it has suddenly developed a broken thread and traditional methods of trying to reconnect the thread by means of flicking the device has not had the desired effect. Can anyone suggest any other tricks which might be worth trying? The break in the thread is typically 1/4" in length.

[GreensandsParticipant @greensands]

[peak4Participant @peak4]

The only ones I've had have a little expansion area at the very top, where the bore is a larger diameter.
I've successfully heated up the bulb, such that the alcohol or mercury extends all the way up the tube, just into the expansion bit at the top.
When the fluid cools, it pulls the whole lot down again.
For obvious reasons, care is required so the contents don't expand too much and burst the glassware.

Bill

[Dave HalfordParticipant @davehalford22513]

As Bill says, overheat and the bulb blows clear off.

[Rod RenshawParticipant @rodrenshaw28584]

+1 for the idea of overheating to the extent that the level goes up into a larger diameter part of the glass tube, and I also see the risks.

I note that the OP's thermometer reads 0-50 degrees. If the thermometer is put in a freezer, in a vertical position, will the alcohol level drop into the bulb, and then expand in an unbroken column when the thermometer is returned to room temperature? Don't leave it in too long, you don't want the alcohol to freeze!

Rod

[Neil AParticipant @neila]

Freezing point of alcohol is -114.7 degrees Celsius. Most domestic freezers only go down to -18 or there about. I don't think you will have a problem there.

I think I would try the freezer first, less danger.

Neil

[Richard MillingtonParticipant @richardmillington63972]

As above.

Last one I did was by over heating so the "bubble" went to the expansion area, (just dipped it in a hot kettle) easy to control – just take it out of the water to cool down.

[Author]

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