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Idea Thermos(R) flask cut away

2 months 2 days ago #41801 by D.B.Ferguson
A while ago I had an attempt to cut a Thermos(R) flask in two. I did this by laying the flask insert on it's side and filling with clear resin.
This was a bit optimistic as the mass of resin was too big. The combination of thermal shock and shrinkage caused a poor end result. It did work, after a fashion, but If anyone wishes to follow suit: only poor small quantities of resin at a time.
A better result was obtained from the easier to find (modern), stainless steel flasks. The one I had was a £5 500ml one from Wilko.
I used a dremmel type tool with several abrasive wheels (a hacksaw initially), and finished with tin snips. Coarse Emery paper at the end to smooth edges (and file to de-burr). I just need to mount in plastic.
Image shows the half with the air exhaust port highlighted.

Technicians: providing solutions and more.

David Ferguson B.Sc.

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2 months 3 hours ago #41804 by AndyG
I assume, if shrinkage on the first attempt was a problem, you used polyester resin?
2 months 56 minutes ago #41806 by D.B.Ferguson
Spot on Andy...
first attempt at resin casting too!

Technicians: providing solutions and more.

David Ferguson B.Sc.
1 month 4 weeks ago #41807 by AndyG
Poly is cheap, clear, robust and fairly uv stable and cures quickly. However it is quite nasty to use due to fumes and the heat production during curing can be high so thin layers are the order of the day. It also shrinks quite a lot on curing and if exposed to the air the final layer will need a wax additive to make it cure properly.
Epoxy has to be the correct type to self-degas, be the correct version to be water clear, may not be very uv stable and costs much more ... On the other hand it's mechanically robust, can be selected to give off less heat on curing, layers can be thicker, shrinks less and is much nicer to work with.
You pays your money :-)
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