ARINC instrument sizes

[ChristiaanJ]

Question from an ancient.....

How is, as an example, the ARINC 5-inch instrument standard (5 ATI) defined?
I can't afford a new copy of ARINC 408A, and after googling left, right and centre, I'm confused.

Does the 5" refer to the cutout?
Does it refer to the available 'square' on the instrument panel? It would seem not, since bezel dimensions I've seen appear to go beyond that.
Does it refer to the instrument casing (which is really the same as the cutout), but in that case what is the size of the 'square' on the panel?

Mostly asking for somebody else, but I've now been so often baffled myself, that I thought I'd venture out here and ask.

(I know, there's 3", 3.5" etc. etc., that's not my question).

CJ

[ChristiaanJ]

Sorry for pushing this back up the stack a moment.
I know it's halfway esoteric, but then mabe the one person who could answer it doesn't log on every day...

CJ

[skiingman]

Does this help? Hope I'm not repeating something you've already found with google...

Mod-A-Can Inc. Product Catalog, Arinc 408A Indicator Cases (http://www.modacan.com/catalog/Arinc408A_p.html)

It appears that "5 inch" refers to the nominal dimension of the can, while the bezel is considerably larger. Your question is how it is defined though, so I fear a mere table of actual dimensions may not help. Bump for an interesting question in any case.

[ChristiaanJ]

skiingman,
Thanks! I've found similar, but that's one more.

So far, things point to the "5 ATI" referring to the size of the cutout in the panel being a nominal 5.000".
Same as the 4 ATI cutout being 4.000". and the 6 ATI cutout being 6.000".

To help the confusion, 2 ATI corresponds to 2.200" and 3 ATI corresponds to 3.200", but let's not quibble over that...

I do start wondering if ARINC 408 does go beyond defining the case cross-section, or does it leave bezel dimensions, mounting (front-face screws, clamp, etc.) and hence the front panel "footprint" to the instrument and aircraft manufacturers.... ?
Does anybody else have more info?

CJ

[forget]

... or does it leave bezel dimensions, mounting and hence the front panel "footprint" to the instrument and aircraft manufacturers.... ?

The sole reason for ARINC Specs existence is interchangeability between manufacturers. So, the only things that must be common are the size of the panel cut-out and the wiring interconnect.

[ChristiaanJ]

forget,
Thanks.
You're very likely right. The only question then would be: "is there a limit on bezel dimensions defined?". They usually DO spill over slightly, if only by a tenth of an inch or less. The same applies to some of the mounting hardware (trays, clamps).

CJ

[Avionics Mounts Inc.]

HI, I was doing some web searching and ran across this post. I think I can answer all of your questions. The 5 ATI cutout is 5.010 X 5.010 and 6.395 across the corners. The location of the screws are 4.810 on both the x and y axises, centered on the cutout. Arinc 408 (a) does call out bezel sizes for the standard ARINC bezels also. If you need more info let me know. I am considered one of the ARINC 408 experts in the field of Avionics Mounting.

Regards,
Dean Johnson
Avionics Mounts Inc.

[ChristiaanJ]

If you need more info let me know. I am considered one of the ARINC 408 experts in the field of Avionics MountingDean,
It sounds as if I've found the right door to knock on.
I'll send you a PM with my e-mail, to explain the "why" of my question in more detail, without boring everybody else.

CJ