Cnc for fade anodizing titanium

I’ve fade anodized before by pulling the Ti out by hand as I crank up the voltage on the electrolyte.
But let’s say you want to do a consistent job of anodizing a short run of parts, and let’s say that you have a power supply that’s capable of 200V with plenty of current, and it has a GPIB interface and you have a GPIB adapter that kinda works (by which I mean, it’s a prologix and I’m using minicom to send it commands.)
How would you make something that would smoothly lift a part out of the bath?
Some possible routes: use a linux laptop sending usb-gpib commands to the supply, and sending usb commands to an arduino that’s driving a stepper motor with a pulley on the end, lifting the part out that way.
Use just an arduino and try and scrobble together a gpib-master-derived program that sends out commands from the arduino itself.
Skip the GPIB entirely, wire the supply up as an amplifier (it’ll take a 0-5V input and turn that into its full rated voltage as output) and use an arduino with a I dunno 10 bit R-2R DAC, and driving a stepper motor.

Something else entirely?


Or an rPi - Raspberry Pi for GPIB and data analysis: very easy and fully equipped - Page 1

and ya, I’d shoot for either stepper motors(geared so there’s holding force without power) or some geared DC motors with encoders or even a vehicle windshield wiper motor.

Sounds like a fun automation project.


A reason I really like the windshield wiper motor idea is that it would be interesting to do an arc fade on a sheet.

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So an Arduino can drive the PWM( speed control ) of a windshield wiper motor using a L298 H-bridge.
There are dozens of examples if you google “arduino L298” or add “DC Motor” to the search.

The L298 has a DC power input and this is what the motor will run at( typically 12V for a wiper motor ) and there are 2 direction pins which the Arduino code will set one HIGH and the other LOW for one direction and the opposite for the opposite direction( If I’m remembering this right). Then there is one Enable pin which control with pulses to control the speed of the motor.

It’s a good learning experience if you’ve not programmed Arduino and if that’s the case, I would say you should get your Arduino and L298 from and follow the Learning section with the L298. It’ll explain how to wire it and how the Arduino code controls it.

The wiper motor is a worm gear so it’ll do a good job at holding your parts in place even when depowered.


I’m currently using a 298 to drive a core memory test setup, but would not have thought to use it to drive a wiper motor. It was my thought for a stepper, though, for a linear fade.

L298N is the full name -

if you want more control as in a stepper motor then you can add a multi-turn POT or an encoder to the wiper and you’ve got enough control to do repeating fade patterns.
Like this one: GitHub - dlarue/dcservo: Position control of DC motors
for for dual motors(geared motors off ebay with builtin encoders) and an ATMega 2560 - GitHub - dlarue/dcmotors-to-stepper-control: This Arduino sketch is used to control 2 DC motors having 2 optical encoders by stepper motor step / direction signals for each motor. The discrete L298N H-bridge(s) are used.

There are many examples out there on this stuff also.

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