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Hole for squared switch / button

f14av8r

Well Known Member
How do you experts fabricate an instrument panel hole for a switch / button that has a flat side. It's obvious to me why the flat side is there - to keep the device from rotating - but I can't figure out how to fabricate the hole to accommodate the flat side.

I would usually use a step drill. But that obviously won't create the flat side that will create the anti-rotation.

Thanks,
Randy
 
How do you experts fabricate an instrument panel hole for a switch / button that has a flat side. It's obvious to me why the flat side is there - to keep the device from rotating - but I can't figure out how to fabricate the hole to accommodate the flat side.

I would usually use a step drill. But that obviously won't create the flat side that will create the anti-rotation.

Thanks,
Randy

The experts would cut it with a CNC laser while making the entire panel but us mere homebuilders usually draw out the finished shape on the panel, remove the most material possible by drilling with a step drill, and then finish the opening with hand files and/or a dremal tool.
 
The experts would cut it with a CNC laser while making the entire panel but us mere homebuilders usually draw out the finished shape on the panel, remove the most material possible by drilling with a step drill, and then finish the opening with hand files and/or a dremal tool.

That. The use of a hand file is the very first, most fundamental, machinist skill required in any apprenticeship. Enjoy the experience of executing basic craftsmanship.
 
I have drilled a series of closely-spaced small holes (@ 1/16" dia.) along the interior of the planned hole and then used small files to work the rough edge up to the finished configuration. You'll feel like an olde-tyme cobbler working on that new-fangled flat panel display.
 
Most typically a special washer is used. The washer has the flat on the ID to anchor the switch to the washer and a small bent tap on the exterior to anchor the washer to the panel. The hole for the tab is drilled in the panel Digikey and others sell these and a switch with a flat in the threads often comes with one.

Making the hole with a small file is doable, but much more work. The imperfectly round hole is typicall covered with a washer so it only needs to be precise enough to securely hold the switch.

Larry
 
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Scribe the outline of the hole. Drill the biggest hole without going outside the lines. Use a Dremel tool with a cutting bit to get close to the line then finish up with a small flat jewelers file. Especially the corners. Practice a few holes on scrap material to build your confidence because if you screw up the one in your panel you?ll be yelling words that just aren?t polite.
 
slot vs. flat

Another example of the keyway washer ..
http://www.bandc.aero/toggleswitchkeywaytabwasher.aspx

The panel is thick enough that one may file the tab a bit and not drill it?s matching hole all the way through. Very clean and fast relative to filing if the switch supports it.

dave

Yes, but that type won't work on the switch thread that has a flat. It's designed for the switches that have a slot in the thread, just like the switch in the B&C page you linked to.

The tabbed washer for a flat thread is much harder to find.

Try a search in DigiKey as Larry suggested to find one. :)
 
I built and have maintained the airplane without a band saw, just a hacksaw-drill-die grinder-dremel it close and file to finish. If I want a crisp square edge I clamp a sacrificial angle to the piece as a file gauge.
 
Yes, but that type won't work on the switch thread that has a flat. It's designed for the switches that have a slot in the thread, just like the switch in the B&C page you linked to.

The tabbed washer for a flat thread is much harder to find.

Try a search in DigiKey as Larry suggested to find one. :)


good to know thanks Gil!
 
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