El Beast - Initial design phase, comments and critique welcomed!

[Zeeflyboy]

Hi guys,

Sorry there hasn't been any progress recently - a general mix between work ramping up for the summer, enjoying the nice weather, with a dash of laziness and a sprinkle of lack of disposable income.

Anyway, thought I'd share what little I have managed to do - the pump and agitation setup for my anodising tub. As mentioned previously I wanted something a little more reliable than bubbles and something that would reduce fumes/slpashing/condensation.

So I scrapped the two pumps I originally ordered, as after disassembling them I found that they have metal springs for the diaphragm despite being labelled as suitable for corrosives. Shame. Ended up ordering a big proper mains powered chemical pump instead which is designed specifically for this sort of stuff.

First up since the pump isn't self priming and I want to be able to put a sealed lid on the container when not in use I needed to make some bulkheads for the "tank" (the tank is a polypropylene storage container). I managed to find some fibre re-inforced polypropylene filament for the 3D printer which is perfect for making water tight sulphuric acid proof fittings.... albeit a slight PITA to print with due to warping. This is the end result, and it accepts a large Viton O-ring which then seals the fitting against the tank wall. I then 3D printed the "nut" out of ABS since it's less of a pain in the arse than the polypropylene filament and isn't exposed to the bath.





With pump (attached by pure EPDM tubing)




Leak tested for a few days and nothing to see. Happy times...


I had also read a paper on using eductors in anodising tubs which sounded interesting - for those that don't know they basically work on the principle of flow multiplication... a high speed jet is shot out the nozzle and induces a flow through the cone to improve mixing. I couldn't really find any decently designed ones that were small enough for my purposes so I designed some myself. Again 3D printed these from the Polypropylene with a G1/4 mounting thread. I also needed something to hold them at the right angles for a good spread and designed a block for them to screw into.








And then connected them up with 12mm PVC tubing which is a tight push fit.




To test whether this work achieved anything at all I figured it would be interesting to put some food dye into the tub and see how effectively the liquid is being circulated and mixed. Pretty happy with the result! I like the second view in the video, looks cool and you can see the eductors doing their thing quite nicely.




Got a bit more work to do on getting a nice setup for the cathodes and bus bar, but shouldn't be too long now until I can try some anodising.