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By Rob P
When instruments are quoted in mm or cm where is the measurement taken from?

Is it across the glass or the bezel?

Rob P
AFAIK the bezel, but don't start cutting on my say so!
No it is not the bezel or the glass size.
The size quoted by the manufacturer is normally the size of the hole you will need to cut to take the instrument. 57mm (2 1/4'') or 80mm (3 1/8''). In other words it is the main body size of the instrument.
The actual size of the instrument ( bezel size)sitting on the panel will be larger obviously otherwise it would just drop through the hole.
Edit:- A caution though, some manufacturers quote 57mm when in reality the instrument measures 58 or 59mm so it is always best to measure each instrument body yourself to confirm.
Last edited by Shoestring Flyer on Wed Feb 14, 2018 11:56 am, edited 1 time in total.
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By Rob P
OK, got that.

Does anyone happen to have an 80mm VSI, preferably reading up to +/- 3,000fpm, that they'd like to convert into pound notes? (or coins)

Rob P
Maybe, I'll ask my mate.

I am intrigued your team's keenness on a large VSI and the prominence you want to give it.

In a glider yes, but in an RV?
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By Rob P
The size matches the existing three clocks

It's a VSI as we already have steam ASI, Alt and G Meter

We are only adding it for reasons of symmetry

The hardest information to get at a glance from the Dynon are G and RoC/D

Rob P