PCB routing/milling

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gyraf

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Stumbled upon some interesting stuff - haven't had time to check out fully:
Voronoi toolpaths - converting Gerbers to pcb routing outlines (isolation milling)

Background article:
http://ftp.cnchungary.com/Varsanyi_Peter/Pdf-ek/PCB%20milling/PCB%20maras%20-%20valami.pdf

Software:
http://sourceforge.net/projects/visolate/

Anyone here knows it?

Jakob E.
 
That's awesome, very organic!

I tried downloading it, but the.jar file wouldn't run... Just made my cpu fan spin up, then my desktop refreshes and then nothing...

 
ruffrecords said:
Interesting. The resultant PCBs are strangely attractive.

Does anyone besides me see a standing man working at a computer terminal in that pcb on the far right?  Or should I quit coffee for the rest of the afternoon?  :)

-Jack

 
I've tried it in the past but it doesn't have very good support for gerbers from different layout software.  I can't remember which ones worked for me because I was so frustrated and then gave up.

It also runs in a webpage or download as a Java applet.

I love the concept though.

Vetsen
 
interesting, but as they point out:

"One downside to the
Voronoi method is that it may increase the parasitic capacitance
and inductance between traces because it often results
in a longer section of close proximity along the boundaries of
adjacent traces."

might be of topic, but i've been using the "fab modules" lately to generate toolpaths from .PNG files for the Roland Modela.
http://kokompe.cba.mit.edu/dist/

greetings,

Thomas
 
hobiesound said:
might be of topic, but i've been using the "fab modules" lately to generate toolpaths from .PNG files for the Roland Modela.
http://kokompe.cba.mit.edu/dist/

greetings,

Thomas

I remember haring about the Modela a few months back. What is it like for making PCBs?

Cheers

Ian
 
ruffrecords said:
I remember haring about the Modela a few months back. What is it like for making PCBs?

Cheers

Ian

The modela is very nice, but don't expect too much support from roland. The supplied usb to serial cable does this to pcb's:
6916268537_39a191dbfd.jpg

if you buy your own cable it works perfectly. quite fast (at least for small smd boards for microcontrollers and depending on the size of the bit and how you calculate the toolpaths). And you can use it to mill 2.5D and scan 3D objects. It is really precise btw. The model i've been using has no variable spindle speed but there is a model where you can set it.
MIT fablabs all over the world stock them for pcb making, mold making and 3d scanning, so as a consequence the center for bits and atoms and Machines That Make at MIT are all over the machine making custom drivers which are linux, windows and mac compatible. BTW a friend of mine here in amsterdam is maintaining a wiki on the modela and the stock driver issues. http://frisojorisgerson.nl/modelawiki/index.php/Main_Page

greetings,

Thomas
 
hobiesound said:
if you buy your own cable it works perfectly. quite fast (at least for small smd boards for microcontrollers and depending on the size of the bit and how you calculate the toolpaths).

Roughly what sort of time would we be talking about for a 100mm by 160mm Eurocard PCB?

Cheers

Ian
 
at the moment i'm milling a 42mm x 35mm pcb and i'm using a 1/64" bit at 4mm/s with the toolpatch cutting everything that's not needed (instead of just the outline which takes considerably less time). It takes the machine about 10-15 min. If you optimize the toolpaths and increase the milling bit size and speed you could decrease that to 5-7 min.

greetings,

Thomas
 
hobiesound said:
at the moment i'm milling a 42mm x 35mm pcb and i'm using a 1/64" bit at 4mm/s with the toolpatch cutting everything that's not needed (instead of just the outline which takes considerably less time). It takes the machine about 10-15 min. If you optimize the toolpaths and increase the milling bit size and speed you could decrease that to 5-7 min.

greetings,

Thomas

OK, so assuming time scales with area we are talking about an hour or so for a Eurocard sized PCB - that's reasonable.

Do you use it for drilling PCB holes as well?

Cheers

Ian
 
ruffrecords said:
Do you use it for drilling PCB holes as well?

Cheers

Ian

yes an hour sound about right for a eurocard. Yes holes are possible too. I haven't milled any holes with it, because the classes i'm using it for are smt/smd only. Milling the holes would be another job along with cutting the pcb out. We do use only FR1 and FR4 because fiber prints are too hard to mill with the modela and the dust is hazardous. Not mentioning how fast the bits will dull.

Saw a student page where they milled out a board for a bga package with a 1/100 inch bit. So that tells a lot about the accuracy of the machine.

On a side note: this week i'll be milling a machinable block of wax for making 3d molds on the modela. Looking forward to see how that pans out.

Greetings,

Thomas
 
I've tried copperCam gerber to gCode followed by Mach3 with some success. Planet CNC's software plus DIY USB board also looks promising, the gerber import gives you a choice of isolation routing of signal layers or engraving for the silk screen. I'll report back once I've hooked it up to my cnc...
 
I've often wondered about things like this (the voronoi pads).
Personally, since the gcode export from Eagle is not a least-cost path traversal, a better use of a mathematics background would be a gcode reordering program to minimise the cutting time of the CNC file (using either least cost traversal or, a space-filling-curve reordering of the points).

The main interesting property of the voronoi pads is that they have the largest surface area possible for each conductive path (since a voronoi cell is defined as the region containing the set of points that are closest to the centre of each cell, with regard to all surrounding cells).  Therefore in some ways, this is quite likely the worst possible layout you could do....  Also the dual graph of that PCB, would also be the delunary tesselation (the smallest possible set of triangles that connect the pad centres togeter), which would make a SERIOUSLY cool silk-screen.... - might have to try that one day just for the hell of it.
 
I'm not sure if I should start a new topic. Mods, please do if appropriate.

How are mulitlayer PCB's constructed? I can see milling the layers separately and gluing them together. I don't understand how a via is made.
 
In the pro world, it's done just that way, vias are simple plated through holes, and they end up connecting each layer that is touching that via. I don't know what sort of adhesive they use... epoxy?
 
To electroplate something it would have to be conductive first. The hole would have to be treated with a conductive solution before plating. Is the copper on a copper clad board electroplated or fastened with adhesive? Maybe FR4 is designed to adhere to electroplate? If you put the whole board in a bath it would be hard to control the plating. Maybe they make the vias before engraving the PCB?

Just thinking out loud.
 
The boards are etched from sheets of copper clad, then the holes drilled, then a conductive ink is applied through the holes and then electroplated.
 

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