Rough 3/4 Scale Tom Thumb Locomotive Restoration Help Needed

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hddennis
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Location: Byron, Georgia

Re: Rough 3/4 Scale Tom Thumb Locomotive Restoration Help Needed

Post by hddennis »

Thanks for responding. Yes the white part is a 10mm dowel I was using to check alignment. All the bushings are 1/8th NPT and the one in my picture was damaged before I got it and broke away from the boiler. The white thread is something I was using to see how much sealing material I could get under the nut (almost none) and I was trying to get a good tight fit on dowel so I could duplicate accurately where the the bushing needed to be re-attached.
Speaking of sealing, what is recommended to seal all the threads on this boiler during re-assembly?

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Bill Shields
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Re: Rough 3/4 Scale Tom Thumb Locomotive Restoration Help Needed

Post by Bill Shields »

If the threads are taper then the options are Teflon tape carefully applied or loctite thread sealant....not thread locker.

Considering the age.. the original glass was probably not 10 mm and would have had enough clearance to get an oring in place.

3/8 od glass would be a better choice. That glass looks to be an uncomfortable tight fit.

Remember..the fittings are not going to be perfectly in line and things move around as they get hot. Any pressure on the glass and kiss it goodbye.
Last edited by Bill Shields on Mon Jul 12, 2021 9:32 pm, edited 1 time in total.
Too many things going on to bother listing them.
hddennis
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Joined: Sun Jun 27, 2021 7:49 pm
Location: Byron, Georgia

Re: Rough 3/4 Scale Tom Thumb Locomotive Restoration Help Needed

Post by hddennis »

Thanks Bill, I was wondering if that was an option as it seemed like the grommets would work then.

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NP317
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Re: Rough 3/4 Scale Tom Thumb Locomotive Restoration Help Needed

Post by NP317 »

All steamers:
Remember that the borosilicate glass tubes and their sealing washers should be replaced every several (<5?) operating years.
The tubes will get micro cracking visible with age, and the seals will harden and begin leaking. Then they are past their safe lifetime.

This past year I replaced the glass gauge tubes on one of my locomotives, on my steam launch boiler and on the 10-ton steam traction engine I work on at our local museum.
Pic attached.
RussN
IMG_3960.JPG
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