Do you think an ESC could run my HDD? Can I use my powersupply ? Usually battery are used ... as far as I understood with PWM I can trigger the speed for the ESC. The ESC has usually 3 wires for the motor, that would fit to my HDD.
Yes, I assume regular RC style ESC will run your HDD motor with no trouble. I am not sure about the supply voltages but it's safe to say that it would be more than 5V and less than 12V (unless you want to break the sound barrier with it
). If you have one, it may be a good match. In my case, I'm using the spin-up circuit as a kind of (uncontrollable) ESC - to say it differently, I want to keep the circuit that spins the disk and one that pulses the laser diode separate because I don't see how one Arduino MCU can handle both.
Mirrors: I made the same experience in my tests, the CD as mirror maybe not good enough. In the end the glass mirrors are still the best (but maybe too heavy)!!
Well, I would still stick to CD for safety reasons. I already had one mirror break off the holder at high RPM. You would NOT
want this to be a high speed glass projectile - this just spells trouble. I don't know how stable the CD mirror will be in the long run - the surface had started to deteriorate where I was not careful enough to touch it - but it is so much safer than glass. It's up to you, obviously, but I will stick to your original plan!
I was also thinking how to calibrate the mirrors to the correct angles? you are right we need a special part. What angle are you using between the mirrors? With 5mm distance between the dot lines in 1m distance, we need 0.28 degree angle between the mirrors. Which is not much! (angle=5mm * 360 / (2 * 1000mm * pi).
Glad you brought it up! I am having problems with the 3D printed holder I got from Shapeways (arrived yesterday!) and that made me take a more careful look at the model. I originally had the faces at 1° to each other but you are correct, the lines would be too far apart. I was not sure how the 3D printed part would reproduce small angles but now that I got the part from Shapeways, I see that tiny angle differences will not be a problem at all. I have since re-done the model and created one with faces 0.25° apart. The only thing that remains to be seen now is how much the layer of glue under the pieces of CDs will affect the tiny angle variations.
If you like, you can order (I think - not yet an experienced enough Shapeways user) mirror holder here at my Shapeways page
. This link leads to the 0.25° version. If you still need the 1° one, go to the link that shows all my Shapeways models (I only have two for now) and select the other one. If the ordering process does not work for some reason, please let me know, I want to make sure that people can get it there.
Thanks for joining the project - much more fun to make it together!
How could I not?! This sounds like an exciting project! Besides, it combines my two passions: lasers and motor control