Simplified Enigma Replica

So while I'm waiting on parts for my next stab on the rotor output contacts, I took a stab at the tooling that I will need to sand the output contacts flush to the output contact plate.

The idea is to use a sheet of glass with sand paper glued to it and use the rig to keep the contact plate parallel to the surface of the glass. The three corner screws can be used to  adjust the parallelism. The shaft that the contact plate is mounted to will be free to float up and down in drill bushing pressed into the plastic frame. The spring between the pressure knob and the frame will allow the frame to keep the contact plate parallel to the glass when just pushing down on the knob and moving it around on the sand paper. I think it will work.

I've often heard that no plan survives meeting the enemy, well some times a design doesn't survive meeting the hardware. This week I was attempting to put together an output contact plate for the rotors and discovered that the M2.5 standoffs that I was going to cut down for the contacts had the female holes drilled so deep that there wasn't enough material left after cutting them down to get a flat face. Now I could jut get some longer standoffs, but in looking at the physical parts I've come to the conclusion that the 4.67mm hex body on the standoff doesn't leave enough material in the contact plate to make me comfortable. This is an area that I was concerned about when I designed the part. I'm also not happy with the amount of waste I would generate if I use longer standoffs. So I decided to look at the design again. My first thought was to switch to using M2 standoffs, and to turn the standoff around so that the male threads would be the part being cut off. A M2 screw would then be used to hold the standoff in place and provide the electrical connection from contact to circuit board.

But unfortunately that will not leave a very bit target for the next rotors input pins.

So what I'm looking at using custom contacts that are made from 4mm brass rod.

Now comes the problem of how to manufacture all the contacts without braking the bank. My solution is a custom 3D printed tool.

The cutter is made from a piece of 1/4" high speed tool steel that will be ground to the required profile. The brass rod will be chucked in a drill to spin it, and I will just squeeze the cutter parts together by hand. The resulting parts should separate from each other easily.

The tool is not complicated, nor is the profile that I will have to grind into the tool steel. So as soon as I can get my hands on the required 4mm bearings and some 4mm brass rod I will give it a go.