modding rotary switches

[tiburon]

Hopefully someone has a trick that will make this easy :
I'm trying to mod some rotary switches so they will take a double shaft and for the life of me I can't do it. I have managed to drill a hole exactly in the middle but then you have to cut the spring in two parts and then shorten them so the little balls will fit again at both sides of the new shaft but they have a life of their own. It''s simply not possible to put two springs and two balls in at the same time
I've been trying this for three months now and wasted 5 switches or so.
I can't finish my EFIS and brake panel without these horrible switches.
So how do people manage this or is there someone out there whom I could pay to make me a couple of these life wreckers?

frustrated

Martin

[capetonian]

I know the feeling , ... I have to take a crack at making mine soon. I bought some alimunium U profile in Bussem which I plan to use to hold the two switches in ... I should be getting a drill press soon. My problem is not the springs, . it's drilling the holes.

[tiburon]

Actually, once you have the drill press, it's not that hard. Take the switch apart, remove the spring and balls, shorten the shaft so it doesn't stick out anymore and put it back together. Clamp a piece of wood under the drill press and drill a hole the size of the collar (10 mm) of the switch (the part you stick through a panel). Put the switch in the hole with the collar facing down. Now without moving the position fit a 6 mm drill and you can drill a hole exactly in the middle.

[Westozy]

Hi Martin, I have a customer who is building his own B747 MCP and EFIS units. He requested some dual concentric potentiometers and also some dual concentric rotary switches. Another one will have a rotary encoder in the centre and a rotary switch on the outer knob (for heading & bank angle). I have only made the dual pots so far but the others will have the same construction method which is a mounting plate and a couple of small gears.


Cheers Gwyn (Westozy)
Aerosim Solutions

[tiburon]

Thanks Gwyn. I was aware of your solution but I don't think it is going to work for me. I'm using the Hispapanels circuit boards and there's just not enough room in the EFIS to incorporate your design. Also it doesn't look as if the shafts are 6 and 4 mm, are they ? I couldn't use my knobs.
Also the lower two rotary switches on the EFIS just have a hole in the middle to be able to connect to the push button switch under it.
Now If you could make some rotary switches with just a hollow 6 mm shaft through them I would be your first customer

regards

martin

[ridgenj]

Hi Martin, I have the same problem. Manolo made 10 dual concentric encoders that fits his PCB's. The price was reasonable? The dual concentric knobs are now my next problem, specially the ones with push botton in the center. Simparts.de is willing to make the kobs for me but the price is according to the customized request. I am still shopping for a solution
Cheers
Luis

[tiburon]

Luis, I persevered and after ruining about 6 of them I finally got the hang of it. I'm now able to make them with reasonable accuracy. I also made the two 60 degree indexing switches for the EFIS. Simparts advertizes the knobs for 45 euro's, that's not too bad, is it ? I wouldn't know another source.

regards

Martin

[mpl330]

Martin,

What's the 'trick' to putting them back together then?
Got a few to do myself and have the shafts drilled ok but not cut the springs and put the ball bearings back in yet...

Cheers
Mike

[tiburon]

Ok, Mike, I'll try to explain (not my first language this)
Cut the springs so they are a little under the surface of the rotor part of the switch (where you put the new shaft in). I use a tiny amount of super glue so they won't fall out again. Put the rotor back in the top (black?) part of the switch. The rotor has cut-outs where the balls go and on one side of the top part there's a little gully. Position the rotor so one of the cut-outs is opposite the gully. Now lift the rotor gently and because you cut the springs a bit under the surface of the rotorpart you can balance a ball on the spring. Now push it in (I use a chopstick) at the same time pulling down on the shaft. That's one. Keep a downward pressure on the shaft at all times. The other one is easier actually because you can just roll it down the little gully. Lift the rotor a tiny bit so the other ball won't fall out, use the chopstick trick and hey presto, they're in.
Now I discovered it's very important that the rotor part has some sort of upward pressure applied to it (towards the top of the switch)
That is because you took out the bottom part of the rotor which in it's original state was resting on the bottom of the switch and the rotor is too low now in the housing so the stop in the upper part doesn't stop the rotor anymore. I hope you understand what I'm trying to explain.
To overcome this problem I put a little spring on the shaft at the bottom. Works perfectly.
Let me know how you get on.

cheers

Martin

[tiburon]

Could you tell me how much that would be?