Planning the first prototype
Hello,
So the best way to get this done is the now getting ol’ motto fail fast, fail often.
I started by drawing this 3D model that resembles ChaN’s design but closed encasing.
It is slightly bigger than ChaN’s by 1.5 mm but that is not bad at all for a first iteration that will certainly be improved.
This model is composed by 4 parts:
Front cover
Main cover
Intermediary structure
Back cover
And this is how it should look everything together:
How I hope in the end it will look like
The four parts are assembled with some snap in features that I also hope won’t bring instability to the structure. Otherwise I will change it for a couple of screws running from one end do the other. The hole in the back part is where the cables will come from and there are also a couple of holes in part n.º 3 to pass the wires to the chamber in the back where the electrodes are.
I also added some removable supports where the coils sit to make it easy to replace them.
Coil support structure
Unfortunately I think this version has to many small details that I’m not sure the hackerspace prusa will be able to deal with but we will see during the week once I try printing it.
I’ll upload these files to Thingiverse later as the first iteration but don’t expect it to be usable because I haven’t tested it yet since I still have to make the electrodes and I’m still thinking in some possible alternatives to ChaN’s approach on them.
Reonarudo and 
Jonas O are discussing. 
Daniel are discussing. 
JL Arnal are discussing. 
) to keep the circuit and the laser cool and it seems it worked. Ate least this time it didn’t auto destruct from the laser heating and helps keeping the smoke away from the lens.
Bibek, and 1 other are discussing. 
Jeff Rae are discussing. 
Jonas O 00:57 on 17/09/2012 Permalink |
Hi!
I’ve been looking into using UV-lasing for exposing presensitized PCBs, both by using standard 2-axis CNC and the use of galvos, as you’re getting into here.
The obvious problem with using galvos is focus, you need a motorized optics, and preferably a special type of collimating lens (can’t remember specific name) to direct the focal point uniformly onto the PCB.
So I settled with trying to making a generic RGB projector, using pre-made scanners – hoping to come back to custom built galvos when I have sufficient time and better knowledge of what I’m doing!
Going back to the CNC method – before I invest more thought into it I’d love to have your opinion – would you recommend using paint/etch/acid or pre-sensitized PCB/etch/acid? Or to abandon the idea and revert to more…conventional methods?
As a side note, I’m in the process of tuning the machine to be able to mill tracks directly. However, so many variables and microscopic error tolerances makes it slow – not impossible – to find a working setup.
Awesome to read about your work. Thumbs up bigtime!
//JonasO
Reonarudo 16:08 on 17/09/2012 Permalink |
Hi JonasO,
If indeed you use specialised optics (like an F-theta lens) you actually don’t need motorized optics, they are 2 approaches to get the same result from what I understood.
I’m using the custom galvos just to drop the price range to be able to use this fast technology otherwise if you have no specific interest in galvos just buy commercial ones on eBay or keep using linear movement CNC style for your goal.
I would definitely recommend pre sensitized PCB/etch/acid its faster to get great results with the laser. The paint method was another attempt to reduce costs. Never abandon innovation
Yeap tolerances are pretty hard to deal with specially if your machine is using belts or materials that can have undesired elastic properties.
I’ll be around if you have more questions.