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Anti-rotation notches for switches- overkill?

Steve Crewdog

Well Known Member
Patron
I notice the standard toggle switches have a notch for the switch labels to fit and lock in so they don't turn, does anyone also cut the hole in the panel smaller and then enlarge with this notch like on the starter switch?

Or am I going off the deep end?


Thanks
 
That is a lot of work, a toggle switch doesnt get twisted like a key switch.

Most of the toggle switches I have seen also have an anti-rotation device that is used with a small hole next to the mounting hole. Lots easier than trying to file out the mounting hole and leave a tab in place. https://www.steinair.com/product/12mm-locking-ring/
 
Anto rotation

I plan to fabricate an anti rotation strip. Basically a strip of aluminum the thickness of the anti rotation tab. Holes for the switches and holes drilled for the tabs. Lives behind the panel. No need to drill tiny holes in the panel.
 
I plan to fabricate an anti rotation strip. Basically a strip of aluminum the thickness of the anti rotation tab. Holes for the switches and holes drilled for the tabs. Lives behind the panel. No need to drill tiny holes in the panel.

I think that is a great way to go and plan to do the same. To me, a panel looks so much better if the toggles are all aligned and vertical, versus canted a little to the left or right.
 
I have never found a need for an anti rotation tab. But if you want one, an easy way to make a tab is to press a small tab at the desired location by using a punch with a small blunt end and a hammer. Use a file to square the sides. Practice this procedure on some scrap.
 
When I lay out a panel in CAD I leave a little index tooth in the hole so when the laser cutter makes the holes it leaves that tooth for the anti-rotation groove. This is easy to do when using a laser cut panel. Can't be done with an NC router for obvious reasons. Here is a sample photo showing the indexing teeth. The big hole is for a magneto switch. The switch holes have the index tooth on the bottom of the hole and the circuit breakers holes have the index tooth on the top. You will also see a oval hole with straight sides for a Tyco (P&B) type circuit breaker switch.
 

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My panel drawing has keyed holes for switches and breakers. It was laser cut at sencutsend.com.
 
Per Stein, if you do use the anti-rotation washer, drill the hole for the tab on the forward face (the back side) of the panel. Furthermore, don't drill all the way through the panel, just deep enough for the tab.
Also, that switch will never rotate after the hex nut is properly tightened.
 
Here's a tip for mounting the ACS ignition switch:

Make the 'inny' an 'outy'.
Cut a small piece of AWG 14 house wiring (aka Romex) about 1/8" long.
When mounting the switch, push the Romex into the slot and tighten the switch nut. The Romex acts as a Woodruff key to keep the switch in position.

VV
 
Match drill

I can’t find a bit in my collection that cuts square holes. ;-) Thus round holes and switches. The anti-rotation tab ain’t hard to accommodate.

Funny, I seem to have a drill bit that does rectangular holes. When I try and match drill a rivet hole into a thin sheet of aluminum, the holes come out rectangular. Must be operator error?
 
Funny, I seem to have a drill bit that does rectangular holes. When I try and match drill a rivet hole into a thin sheet of aluminum, the holes come out rectangular. Must be operator error?

Wanna borrow mine that drills slightly oval holes? ;)



Funny, when I started this thread I thought i was overgeeking, but apparently it turns out I'm not. Yeah, I could laser cut the panel, but today I'm having a nice day in the hangar listening to some music (just discovered Santana's cover of "While my guitar gently weeps", check it out), playing with "What if I moved this 1/4" right and up, or down a little bit?, and moving a square around, seeking perfection and keeping my brain from getting old.

Even a day in the hangar doing small thing beats slowly dying in front of a TV.
 

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Another DIY option is to use a punch like the Greenlee No. 732 (15/32” Radio Chassis Key Punch) which punches a keyed hole. I’m not sure if these are still available new but I was able to get one on ebay last year for about $40. Paul Dye shows the process in this video but with a larger panel punch (https://www.kitplanes.com/metal-magic-cutting-round-instrument-holes/).

I searched ebay this morning for “Greenlee 732” and only saw the larger sizes. However when I searched “Greenlee 15/32” I saw two items that had part numbers similar to the parts list that came with mine ((also note the slot in the side of the screw):

Punch: 500 2458.2
Die: 500 2457.4
Screw: 500 2456.6
Nut: 500 5244.6

https://www.ebay.com/itm/115096574065?hash=item1acc4a5871:g:bewAAOSwAaNhkoTs
https://www.ebay.com/itm/115096557758?hash=item1acc4a18be:g:T5oAAOSwid9hkoEM

Here is a picture of a test hole I cut this morning in a piece of scrap 0.063” aluminum (same thickness as the Vans panel blanks). I haven’t actually cut my real panel but have used the punch to create several cheap steel mockups and it has worked well for the Honeywell 2TL style switches and Klixon breakers.

Lance
 

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I shifted over to a very good quality step drill bit. Made a huge difference in the quality of my holes.

edit: TIL (Today I Learned) that even with a quality step drill and punching a starter notch, it's better to drill a starter hole or two before using the step drill bit, because it WILL skate on you.

*sigh*... it ain't if you make a mistake, it's if you can fix/cover it up.
 

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