737 Overhead knobs and switches?

[StephenBalmer]

Hello all,

I would like to ask for your experience and opinion in helping me to make my 737 overhead build.

I am quite happy in understanding the on/off requirements as well as the 45 or 30 degree rotations, but my question is on the ideal physical size of the switches.

I'm building the Simworld overhead and I'd specifically like to know what is the best diameter for the switches,the ideal length of the protruding toggle switch and the ideal diameter of the toggle part. As well as tha, what is the ideal size for the rotating switches, the case diameter, the hole diameter and the shaft protrusion length?

Any guidance you can provide would be super welcome!

Thanks a lot,

Steve

[Sean Nixon]

Hi Steve.

Your choice on switches is limited to what's available off the shelf. You'll find there's a pretty standard range of fixing holes and toggle lengths and fortunately, the 737 switches are all pretty close to what's widely and cheaply available.

First off, is your overhead pre-drilled? What sizes?

Two popular toggle size cut-outs are around 6mm and 12mm (miniature and standard I guess). Note they are only approxiamate sizes, give or take a few fractions of a millimetre. Typical toggle length would be around 18mm.

Rotary switches cut out is around 10mm. Shaft length depends on what your putting on the end, but typically around 10 - 15mm.

Download the Honeywell catalogues for the TL and NT ranges of switches. That's what they use in the real thing (NT for the normal ones, TL for the locking ones). The dimensions are on the last page. If you cant find the catalogues, I can send you a copy.

I'm wiring my overhead as we speak (Engravity) and have most of my hardware, so feel free to ask any questions. I've also got a few toggles spare which you may be interested in.

Sean

[StephenBalmer]

Thanks very much Sean, that is very much appreciated.

Best of luck with your overhead build!

Steve

[fordgt40]

Steve

A point to bear in mind is backlighting. If you want backlighting, and do not have integrally lit fascia panels, then you will find that in some locations the standard sized toggle switches are too large and will obscure the backlight getting to the front fascia lettering.

David

[StephenBalmer]

Thanks very much David, that is a great point as I will be backlighting the overhead.

What size should the switches be then in order that they are not too big to obscure lighting or lettering?

Thanks, Steve

[Sean Nixon]

Excellent point David, something I overlooked as my panels are internally lit.

In that case, you may as well stick with miniature toggles throughout, except perhaps the guarded switches which may have to be standard. Go to your local electronics store and pick up 1 of each, they are only a couple of quid, then you'll be able to see where you might clash with the lettering. The Equip Cooling switches look like an example, just looking at mine.

Sean

[Sean Nixon]

This is my overhead. The majority of switches are miniature with white toggle caps. They were all supplied from FlyEngravity and all the various switches are listed here...

Flyengravity.com - build your own jetliner! (http://www.flyengravity.com/page/shop/8)

I am upgrading nearly all of them and would be willing to sell you the ones which I'm changing. Let me know if your interested.

Sean

[fordgt40]

Steve

As Sean suggests, I went with miniature switches, except for the guarded toggles. My overhead build is documented here

http://www.737ng.co.uk/djb/Overhead%20Article.pdf

David

[Bonehead]

Out of interest any idea what they charge for the genuine locking switches, like on the bleed panel for example.

i was once told that the switches haven't changed since the B17 :)

[Sean Nixon]

The Honeywell locking toggles range from around $25 - $50 depending on its operation. Look for the TL range.

[BuildABoeing]

As David also mentions in the pdf (And I have done the same for my pedestal and MIP): Build in layers / a sandwich.

Layer 1 ======== Panel front
Layer 2 ___________ Plexiglass with all switches mounted/glued in
Layer 3 --------------- Layer with all connectors/pins

On layer 2 you can glue your LED strips. That way your backlightning will now be influenced by the size of rotary switched, as they are mounted on the backside of layer 2, where the LED-strip is on the front side of Layer two.

Layer 3 contains everything you need for interfacing so they are easily accessed.

From what I can see on Davids pdf he used one large piece of plexiglass that covers the whole overhead. I also started out this way with my pedestal (I don't have an overhead yet). But I ended up making all panels as separate units. So the COM2-radio is a separate unit with 3 layers mounted on to the panel. That way you can remove one panel without dealing with all the overhead. And should you make a mistake (a wrong hold, crack the plexiglass and so forth) you only affect one panel and not the whole overhead.

Use M3 HEX bolts to space the layers.

You will need quite a lot in 5, 10, 20 mm. Found mine on ebay and dx.com

Regards Peter

[fordgt40]

Hi Peter

The light plates on my overhead are all individual ones mounted to each panel. That way you can easily remove anything as suggested

One change that I have since made is to daisy chain the led strips on each plate - less wiring

David