homebrew processors and film camera love

Agitation – Let’s not overcomplicate

Agitation – Let’s not overcomplicate

OK, Agititation, the subject that gave me a few headaches when I started doing a fully automated version from scratch.

The whole thing is now massively simplfied and just as effective.

When looking over the internet, most automated agitation devices were either rotary or servo-driven ‘twiddle stick’ systems.

Rotary is a non starter, due to needing a fancy bath and rollers etc. Twiddle stick is it then! Despite people saying ‘inversion is the only manual way’, just using the stick method has never made my photos turn out any worse than they should.

The two best methods I found was ‘Robotic lab monkey’s’  which was then refined by i386.com with their Spinmatic

The latter, went as far as to 3d print a handy stick to save your original.

The spinmatic from i386.com

After looking at these, I started using servo code before actually building anything. It then struck me, all I want to do is rotate the stick for a set amount of time, so why bother with a servo? Why not just a 12v motor and use the relay I already have to power it? No fancy code needed or set ‘millis()’ Just turn the relay on then off when not needed.

I found these slow rpm motors on ebay for pennies, they are 12rpm which might be a bit slow. If so, they do a 30rpm version as well.

Simple chinese slow RPM motor

This was then mounted on an old and spare patterson water seal lid, and surrounded by an electrical box to project it and strengthen the mount. It’ll be removed to drain, add new chemicals so needs to be tough.

I just attached it to the existing twiddle stick by drilling a small hole through both and fitting a temp metal clip to keep them attached. As well as being slow rpm they are high torque so have no trouble moving 1 or 2 spindles. All the screws etc I used are stainless to avoid rusting or reacting with dev chemicals.

Crude but effective

I then added a DC-Style connector to the top, so it doesn’t always have to be attached to the top.