Re: [LUG] nearly offtopic - grommet terminology

[Michael Everitt <michael@xxxxxxxxxx>]

On 23/01/20 18:46, mr meowski wrote:
> Maybe my google-fu has gotten weak but I thought I'd ask you lot before 
> having a tantrum and giving up (that's plan B). There are plenty of 
> practically minded DIY-ers with considerably more experience here so 
> hopefully someone can point out the magic term I need?
>
> For background I'm - reluctantly - doing some case modifications for 
> additional cooling on a Linux box getting racked up in a dusty workshop 
> environment and I need easily removable dust filters mounted in 
> arbitrary holes punched through the case plastics.
>
> I'd perhaps unwisely convinced myself that there must exist easily 
> sourced rubber double-sided grommets that would fit snugly into the 
> circular 80mm/120mm holes I'm going to cut. As it happens, those do 
> exist but seem to only be 'closed' (and are typically called "bungs" 
> apparently) or 'open' (such as are typically used to route wiring 
> through). So far so good.
>
> What I'm having trouble finding is an open-type grommet that has, umm, 
> 'lips' (?) on both the outwards facing rim of the grommet _and_ the 
> inwards facing surface so it can mate securely both to the round hole 
> it's going to be fitted into and then let me neatly drop in a dust 
> filter inside that. So the cross section of the grommet would be a H 
> shape basically.
>
> Make sense? Now I can find H cross-section rubber strips that I could 
> cut to fit and make squared off holes instead I guess but I really 
> struggle to believe that these things can't be easily bought if I just 
> knew what they were actually called. Surely they must be really common 
> but perhaps in plumbing or the air conditioning industry? I've even been 
> combing through Ebay listings for vacuum cleaner parts...
>
> If anyone can clue me in I'd be very grateful!
I suspect you're falling into a crack of unusual combinations of
requirements, which don't occur with enough frequency in 'real-world
applications' for there to be a profusion of options readily available.

Essentially you're looking for a cross between a gasket and a gromit, the
former being the common air-tight sealing, and the latter for simple
non-abrasion between surfaces. The other items of use are of course, seals
and glands for water-tight seals.

You might be able to cut yourself a rubber gasket out of neoprine rubber
perhaps, or another material, or the other option at the 50-200mm range is
a flexible plastic strip in U-formation but is discontinuous in that you
can bend it round corners easily, so the sides of the 'U' are perforated,
whereas the base is continuous.

That's about the best I can offer from my engineering experiences...

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