mechanical switch ideas.

[Lance_Wallen]

I've been fiddling with a few mechanical switch ideas and I'm still not satisifed with any of what I've come up with.

I'm putting these in a case ground mod but the place that the switch will be will be isolated (i.e. not going through teh actual metal case) it's for the positive pole. I'm building an insert that goes into the tube that will have the positive terminal on the bottom and the atty connector on the top and sit inside the tube. I've thought about a plain old push button style switch with a post that connects to small copper rods, one from the battery terminal and one from the center pin of the atty connector as well as a 'spring steel' style flat tab that is attached tot he positive terminal and when you push it down it makes contactw ith the rod from the center pin of the atty connector. Both seem viable but I worry about wear and tear on em.

I need something simple, durable, and mechanical. I don't want to use wires and prebuilt switches from mouser or digikey, I want all my parts except the atty connector to be hand made. I own a small metal lathe and various other tools so manufacturing the parts isn't a big deal. Anyone have any ideas I could.. borrow?

 

[WillyB]

Well the contacts will need some give, pounding two hard metals against each other don't cut. And metals like steel, zinc, copper, brass and aluminum are never used for switch contacts in quality switches.

 

[Lance_Wallen]

well, I know silver, rhodium plated, or silver cadmium would be 'optimal' but how bad is it to use beefed up copper or aluminum for the switch contacts? I'm tryin to figure out either a trigger or plunger style switch that I can machine at home and build at home.

Most of the three amp momentaries I find are entirely too deep to use in a 3/4inch tube without bending the hell out of the posts to get it in and with the design I'm working on that's not an option.

 

[urquidezj]

I use either brass as the entire button or stainless with a piece of brass soldered where it makes contact with the battery, works fine for me.

 

[asdaq]

In defense of mechanical switches, electronic switches are sealed and offer no user serviceability. Quality DC rated ones ought to be made from high quality materials as replacement or failure is not pleasant. Mechanical switches are often easy to take apart and clean.

Duracell recommends battery terminals to be made from nickel for the least corrosion as battery contacts are nickel plated. Digikey carries nickel plated screws if anyone is interested. With my homemade stuff I personally have seen little corrosion on the surface contacting the battery, rather more on the tubes the switch slides in and the tube on the pin. Anywhere there is a solid physical connection I have no problems. Also I'm trying out variations of brass, copper and silver as well as tighter tolerances between brass parts to compare differences.

Lance I get what you mean with switching the positive, but I'm switching the negative and my stuff is probably of little help.

 

[Lance_Wallen]

yeah I decided I'm just going to build the switch assembly out of aluminum because that's what I have and that's what is easy for me to machine. it'll be a plunger style that just pushes down and contacts the two positive leads (one from battery, one to atty). It'll be removeable for cleaning/noaloxing. Since all those parts will be aluminum it shouldn't have much corrosion but if it does it'll be serviceable, the battery terminal will be on the bottom of the assembly that you can take out so it'll be cleanable too.

 

[northhar]

I have been looking into this also. I have been trying to put together something using the contact points from a flasher unit in a car or the point set in the distributor. I figured they were designed to do the job I needed, only in the wrong package.
Still working on it...