My High Power Mag Switch solution

[Chodes]

Finally got hold of some Judco switches. I got them from Lighthound - same switches used in Leef system. Unfortunately looks like they are the "long shaft" version of the switch , I'd prefer as small a switch as possible.
Anyway, here's my home made switch. Used some blank circuit board , some spacers , 3mm screws, fair bit of JB weld (metal epoxy)
The big block of JB weld on the front is intended to act as a heat insulator.
I moulded the epoxy inside an old mag tube so it's a perfect fit.
I had to grease the tube or the switch assembly won't move very easily.
I tapped a hole in the bottom so fixing is via external screw - 6mm so I can use a 6mm stainless ring to secure the switch and use as a lanyard point.
It's a fixed height for the socket obviously- I've found thet height good for most of the Osram 64 series bulbs which I'm (now) using it with.

MK2 switch is almost finished , MK3 I'm going to use a complete Kui kit on the front just to make bulb alignment easier.

 

[Juggernaut]

Neat:thumbsup:!

 

[cnjl3]

That is one hell of a switch!
What supports the rubber switch seal to help keep the guts dry?

 

[rolltide]

Great Job!!!!!

That is a great idea. I will try to do something like it, only I am going to use a stock switch and cut the middle section out. I have been trying to think how to mount the switch between the two end pieces. Now I know, thanks to you.

Roll Tide

 

[mdocod]

great work!!! very nice switch job there!

So you have to drill a hole in the mag for the final connection? I wasn't quite clear on how you were making contact to the body and holding the assembly... Yours Looks really nice for a home-brew

I got my "short" versions of the Judco from digikey. I ordered quite a few, if you want a "short" version to experiment with send me a PM

Eric

 

[Bullet Bob]

If you ever decide to make these for sale I definitly could use a couple. Let us know if you would be willing to crank some of these out.

 

[Lumencraft (Matt)]

+1 for the WTBs Nice work.

 

[Chodes]

Eric , thanks very much for that offer. PM incoming.

Mk2 and Mk3 have been under construction at the same time.
Mk1 just needs something to support the Mag rubber boot (unless I find a different boot.) Good 'ol JB weld to the rescue again for the MK1 switch.

MK2 is much more serviceable , thinking of using the very top of a mag switch for the boot retain solution for that one. It's about 4mm longer than a stock Mag.

MK3 I used a Kui kit. Totally serviceable , the switch itself is a very tight fit, clamped in place by the housing bits. So easy to replace the switch in this one if it fails. Switch housing is secured by 3mm screw , externally.

MK4 will have an internal securing screw as per Mag switch.

MK2:

MK3:

The whole family:

 

[VegasF6]

Very neat work.

Just FYI JB Weld is only good to 500F. JB Kwik is even worse. I had both fail on me trying to fix a BBQ. I had no luck finding a high temperature epoxy that would air dry and was readily availible. I am sure that you are well within that range mind you, just wanted to point it out. Reason being I was considering trying to pot a bulb with it, and realized it would fail.

 

[rpage53]

Just FYI JB Weld is only good to 500F. JB Kwik is even worse. I had both fail on me trying to fix a BBQ. I had no luck finding a high temperature epoxy that would air dry and was readily availible.

Epoxies aren't good for high temperature applications. So called Hi-temp epoxies are only high in relation to other epoxies (which you can melt with a heat gun). JB Weld is a little bit of regular epoxy mixed with chalk and iron filings.
However, if the light exceeds 500oF, you have other problems.

You probably need a ceramic adhesive for your BBQ which can withstand 1000-4000oF.

Rick.

 

[VegasF6]

Rick, hey thanks for that tip. I had given up finding any way to repair it and actually bought a new firebox for the old Weber. But i will still pick up some ceramic adhesive, that sound very handy.

I guess there are reports of ROP builds melting solder from the contact's, probably in excess of 400F. I would imagine some of the high powered 100+ watt projector bulbs run quite a bit hotter than that? So you could potentially have some very high temps. But, I would also think that a bi pin lamp in a ceramic socket, like above, would be fine? The stand offs provide isolation both by ventilation, and simply space. And of course the reflector works as a heat shield in itself.

I dunno, I just wanted to point it out, I know very little about hot wires at this point.

 

[Chodes]

Looks like I'll be testing the JB weld out for heat then..
It was supposed to be my super high temp switch , might be re assigned to more moderate duty.(or install fuse in the tailcap and do some field testing )

My MK3 failed! Only about 20-30 actuations before the switch became momentary only. Was still clicking properly, button was staying in "low position " when on. Luckily that housing is super easy to replace the switch so I've done that. Was using 64458 - about 10A at around 19v, seeing as it failed so quickly, assume it was a dud switch.

I've got the rubber boot secure solution by mistake. On the MK2 housing the switch is a bit low, or the plate on top to high.. As it turns out , the plate on top is just about perfect for generic KD/DX rubber boots. The mag boot also works, but is a little loose. It did not fall in with a bit of testing , but it would be easy to make some thin shims and build it up a little for the mag boot.
I think I'll just use the generic boots. They have plenty of rubber on the bottom for an easy fit.

MK2 - 3mm screw in the top of the switch to correct the low height but retain the plate on top for the generic rubber boot. The plate is 3.1mm below the top of the the top of the switch housing.

Generic boot sitting in place. I think about 0.1 - 0.2 mm higher would be perfect for the generic boot , for the mag boot I think same plate postion , install the complete switch in the mag tube , then fit a small ring / washer / mark position where you will install ring / washer as the mag boot will need a very accurate support.

Can anyone tell me the thread size of the Mag grub screw in the stock switch?

 

[Chodes]

Too easy!
This small plate works great with the stock mag rubber boot.
Now for my MK4 with internal securing screw.

 

[LuxLuthor]

Nice job, Chodes. I can imagine how much time this took you including all the little details. I was able to fit the Judco in a stock Mag D switch after dremelling out a bit of the blue plastic piece & adding 3M #2229 Mastic Tape, then just needed to ground/anchor KIU on top of switch & solder other lead to bottom of Mag switch spring.

 

[Chodes]

Thanks Lux. I've checked out fitting a judco in a mag switch , I'm getting quicker at producing these now though now I'm glad to say.

I'm clearly not a talented designer , I finally came up with an obvious good design, should have been obvious from the start...
I present the MK4!
Not finished yet , got to add a few bits but the main design improvement is done : a 6mm thick aluminium to connect front and back and support the base of the switch and connect front and back of housing. The fibreglass plate on top is a firm fit under the spacers. It does not need to be attached to anything but the Judco shaft ,it can't move anywhere.
The aluminium plate will allow an internal securing screw as per stock mag (blue circle is will be a hole for scre driver / hex key.
I'll fit a Kui kit as per the MK3 switch.
A top plate with rubber boot support will be made as per MK3 switch , but again will not be fixed - just held in place front and back by the end plates , and made wide enough so it just fits inside the mag tube and won't be able to move sideways.
Not a drop of JB weld anywhere :twothumbs

With a short shaft Judco (these are long shaft switches remember) I should be able to squeeze a FET / NTC in there.
This back of this switch will sit approx 10mm forward in the body than a stock mag switch. That should be just enough to allow 3 AW C LIONs to fit in a stock Mag 2D tube.(Mag 85)
If using an external securing screw I could get 20mm extra space inside the tube using single end plates rather than double.
Alternatively switch could be lengthened to fit NTC/FET / other electronics a nice distance away from the heat of the bulb.

I really feel like this has been worth the effort now.

The MK4:

 

[rolltide]

Chodes,
I really appreciate you posting this thread and all the pics. I want to make some high temp switches for some of my hotwires and you have given me a lot of good ideas.

Thanks again

 

[Chodes]

Chodes,
I really appreciate you posting this thread and all the pics. I want to make some high temp switches for some of my hotwires and you have given me a lot of good ideas.

Thanks again

You're most welcome. Makes me happy to think the thread will be of some use.

 

[lctorana]

...happy to think the thread will be of some use.

Very much so. The more so because this switch assembly helps not just M*glites, but ANY torch with a side-clicky switch arrangement. With room to spare for a NTC, FET or even a mini relay.

 

[LuxLuthor]

Chodes, here is the shorter stem Judco inside the stock switch....in this one I put the black part of switch on back side, and used the Mastic tape as filler. Just another option.

 

[flex76italy]

Lux, where is the GND path? :thinking: