instrument holes. 1

[RoarkS]

Okay my fun moonlighting for the evening...
reverse engineering an instrument panel.

These have to be standard holes... I guess I was expecting numbers a little more nominal than what I've got.

Example: Ø3.150" with Ø.150 mounting holes on 2.480 square. I'm sure there's a mil spec somewhere with tolerances???

 

[verymadmac]

The instrument cases dimensions are here
MS33638C, MILITARY STANDARD: CASE, INSTRUMENT, FLANGE MOUNTED, AIRCRAFT

I sure there is one that gives the cut outs but that seems to have escaped me. Alternative location for cut outs used to be the aircraft spruce catalogue, not sure about the current editions.

 

[rb1957]

There are all sorts of "standard" sizes instruments. These days they tend to be large screens.

another day in paradise, or is paradise one day closer ?

 

[WKTaylor]

RS... in addition to VMM's contribution [got me 'membering]…

https://quicksearch.dla.mil/qsSearch.aspx

MS33638...
MS33639 Cases, Instrument, Clamp - Mounted, Aircraft

And for variations/historical... word search [find term1, term2...]

case, standard, instrument
instrument, standard, arrangement

and for 'giggles/gee-whiz'... search... air-std-10

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[berkshire]

When all else fails, Measure the instrument, and size the panel accordingly.
B.E.

You are judged not by what you know, but by what you can do.

 

[RoarkS]

Berkshire,

Yeah I know. I took the panel home. Left the instruments at the hanger. Only had a spare ancient altimeter. VeryMadMac was on point I was just finishing up roughing it out about 2am when he posted it.
Company up in Canada did it the first time for like $800. This time they wanted $3k and some change to make a rectangle in it to mount two G5's. Took me what 3 hours... insane wish I could charge $1000/hr.

 

[berkshire]

RoarkS,
The difficulty I have is that I work on a lot of German aircraft, which use 80mm and 60mm holes in the panels. These holes in metric sizes are just a little bit bigger than their corresponding imperial sizes of 3-1/8 and 2-1/4 respectively. The instruments themselves are supposed to be the same size, however the Germans are are just a little bit freeer with their plus tolerances. An example, a combination 3.125 x 2.35 hole punch (ATS-123C) from Aircraft Tool Supply.
Punches the hole you want and most American instruments fit just fine. Try to stick a Becker aircraft radio 2.265"diameter (.015" bigger) in that same hole, and you will have to use a file to remove a couple of thousandths. Not much, just enough to be annoying.
B.E.

You are judged not by what you know, but by what you can do.

 

[RoarkS]

Berkshire,

Interesting. The original holes made in Canada were 3.150"~ 80mm. I wonder if that was their plan.

 

[berkshire]

RoarKS,
There you go, with an 80 or 60mm hole, most American instruments will be just a little bit sloppy fit. With a metric instrument the fit will be good. However the metric instruments in an imperial sized hole will be good to just a bit tight depending on the tolerances the instrument was made to.
B.E.

You are judged not by what you know, but by what you can do.

 

[WKTaylor]

Ahhhhhh… metric instrument cases... hmmmmm…. verwy twicky

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]