Be curious what peoples thoughts are on this..

This kind of head-torch uses an O-Ring to seal the lens against the body.... they claim its good for 100m of water!!



I understand the theory of how O rings distort to give a seal etc..


I am looking at creating a lamp with a slightly more complex shape where machining an O-ring groove wont be as simple.


Could a similar level of seal be achieved by sandwiching a rubber/silicone sheet between the polycarboante lens and the alloy body do you think?

I used to skim the cylinder heads off my 125 race bikes and machine a groove for an o-ring to sit in so they hold pressure well, but on later mods to the heads, instead of machining a groove, I machined a shoulder on the head and a recess in the cylinder. I then chamfered the outer edge of the shoulder to allow a space for the o-ring. The o-ring was squidged into the corner of the recess by the chamfered edge if that makes any sense. Would that be an option for your application?

Its an option but the new lamp is oblong with different radii either end meaning I would really need a mill to make that happen.

I only have a lathe so was trying to get out of cutting an O ring groove

I've done a fair bit of "trying to make stuff seal" for both vacuum and high pressure. A good closed cell neoprene gasket will work fairly well but you will have to get the surfaces perfectly flat and evenly pressured to get a good high pressure seal. o-ring sealing is really highly dependant on groove size anyway (fractions of a mm either way) but if you have a flexi front face like that lamp you might find a gasket is a bit poo, but so would an oring be. I'll mill your grooves when my CNC is back alive again, for a small fee

Hmm... interesting thought.

I do have data tables here that are pretty specific about O-ring groove sizes etc hence why I didnt want to try and chew them out by hand ....

Yeah you'd be best either neoprene gasketing (lasts well, cheap and easy to cut, seals nicely) or machining, no o-ring will work hand done

unless you can achieve perfectly flat surfaces with no distortion when you clamp them to gether go for an O ring in the correct size groove.