Turing-Welchman Bombe physical build – part 10.

September 26th, 2015

I really need to start working on projects that don’t need so many bloody posts!

Where was I up to? A lot has been happening but the Bombe is getting close to being done. I finished making the panels for it. On the rear panel I soldered on some brass hinges.


The steel weights stopped the thin metal warping from the soldering heat. To hold the door closed I am going to use a magnet. It works as both the handle and the catch. Nice and simple. I also tried folding up the front panels. The first fold was done on Ian’s pan brake. I had to do the rest at home as there was no way to do the second fold in the brake too.


This worked but I wasn’t happy with how it looked with the side panels wrapping right around the front. In the end I scrapped that idea and instead made new side pieces and separate front pieces. The idea being that then the casing is more symmetrical. Each side has panels only on it’s face and the corners would show up as a feature since the panels are done in wrinkle finish paint but the main case would be smooth. This actually worked really well in the end.

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I then started painting things. The frame is painted in zinc rich primer then finished in a subframe black enamel. I got the paints from the local auto parts shop (guess which one)!

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The black is a hard, satin finish. It goes on rather thick and glossy but it self levels and then dulls down rather nicely.


The panels were painted in wrinkle finish black then baked. I ran out of paint half way through and only just finished the remaining side panel today. Since people seem interested in how to do this wrinkle finish (we use it on vintage cars too) I actually made a film of how I do it. I will do a post on that after this.

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I also made small brackets to hold the volt meter and the battery into the case. They are held in place with the same screws that hold the wheels in place.


Most panels I only painted wrinkle finish on the outside. The insides are painted with the same subframe black as the frame. The bottom panel I wrinkle finished both sides so it would match the wrinkle finish brackets that bolt to it. The coating on the bottom wasn’t very even but as this is the underside of the machine it won’t be seen (unless it falls over)! I then started assembling things.

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I did need to make a small modification to one panel. I made a cutout for the wire to pass through the side panel to the LCD module but I also needed a second one to provide clearance for the connector itself attached to the module.


The new style front panels look great and you can see how they wrap around to the inside of the frame and also how the brown panels help close off any holes.


Most panels are in place now as is the electronics board and the drums. Since I only just painted the remaining side panel today so can’t fit it or the rear panel until the paint is dry and hardened. Even then I can’t fit them as I ran out of 6mm screws and had to order more! That is a worry since there were 100 in the last packet. I have used far more screws than necessary from a mechanical point of view, but just enough from an aesthetic one!

I don’t want to give too much away until I am complete but if you watch my painting film you can see more of the partially finished Bombe there.

I still need to redo the script that starts the Bombe code automatically when the machine powers on. After assembling it I turned it on (making damn sure this time everything was connected correctly!) and was shocked when nothing happened. I had forgotten that it isn’t running automatically yet. I connected to it and SSHed in and ran it manually and everything still works which was a great relief.

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