Arcsin Fab A design and construction.


Well, Arcsin is officially underway. I got one axis of the driver working on the breadboard this evening. Still a long way to go, but it was nice to see a motor spinning!


Ahhhhh Yeah!!! Pure clean bipolar microstepping!


The Arcsin fab A board measures only 7" x 5.25".


I still have a few things to adjust, but I'm just about ready to etch the fab A prototype. Laying out all the components on the paper is a must to make sure that everything fits.


Debugging traces is easier with screens of each layer. The prototype board is going to be photo-etched using pre-sensitized PCB material because I think the resolution is too tight for toner-transfer.


Getting close now! Many thanks to my partner Bill for the amazing work that he did with the input section of the board!


I purchased some Harwin track pins from Kensington electronics in Northern California. These pins make vias very simple to put into a prototype circuit board. Instead of having to solder a piece of wire in for a via, you just push a track pin in all the holes, snap them off with the tool, then solder the pins in place.


This tool is going to save hours of labor on the Arcsin prototype PCB. I can't imagine having to populate the 300 vias that are on the Arcsin board by hand!


Here you can see how the pins are formed into a strip. They come in several different lengths for most FR-4 board laminates.


I also built a new etchant tank to prepare for the first Arcsin prototype. The other night, my Pyrex dish exploded on the bench and Sodium Perchlorate went everywhere. What a mess. The etchant caused quite a cleanup job in the garage and many of my tools were stained. So, the next day, I went and spent $10 on a cheap aquarium and built a new tank.

This tank works awesome. The bubbles agitate the etchant enough for a nice even etch and the process is much quicker than without the bubbles. I'm going to get a Titanium aquarium heater to go with this, but I still have to order that part.


To form the tank, I cut a piece of 1/4" plexiglass and glued it into the tank with silicone. The pump and hoses reside in the unused section of the tank. It works real nice.


Here is a shot of the fab A board during exposure. I used my 300W Halogen work light to expose the board for 10 minutes, then it was into the developer. The pre-sensitized pcb is really incredible to work with if you need super fine resolution on your traces.


After developing, it is into the Sodium Persulphate. I'm not as happy with this etchant as I am with the Ferric Chloride. The FeCL works much faster and you can etch more boards for the price. The downside is that the FeCl is messy.


Here you can see the resolution that is possible with the pre-sensitized pcb. Those are 12mil traces!