Similar to the foam idea, in my clocks I use a 2mm thickness of silicone between the (cast acrylic) clamp and the neck of the tube. The silicone rubber should last decades, it is translucent for good looks, and it seems to shield the heat from getting to the acrylic clamp.
As for ventilation, my completely sealed acrylic CRT units don’t seem to have a problem - even the 8mm thick acrylic tube does seem to conduct the 2-3W heat out well enough, I have opened up the case after days of running in summer and it’s just a bit warm in there. Nice mounting design, enjoy the build! -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2213e07a-14b0-41dc-a8dd-82eed5d1b084%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
