Homebrew PCBs

Hello Art,

Thanks for your advice.

How did you end up using the 30 degree V-bit? Have you tried the other
v-bits such as 45, 60 and 90? I am trying to understand how you went about
the process. Whether you bought all the v-bits and just tried them all to
figure out which one was best or if you were recommended that particular
v-bit by someone.

About the CEM board, I read that it is easier on the drill and mill bits.
But, I also read that it emits a weird smell when being cut. Did you notice
something like that? BTW, do you know if the fumes from cutting the CEM
boards are carcinogenic? I have been told this "there are a zillion
carcinogenic phenolic compounds...pentachlorophenol for example." Just
curious, if you gave this any thought.

Thanks again,
Joe



On Thu, Dec 13, 2012 at 9:25 AM, Art Eckstein <
art.eckstein@...> wrote:

> **
>
>
> Joe,
> Yep, you have run into a couple of problems with
> boards being level. It has been found the boards
> will "bow" up in the middle when clamped on the
> edges and FR$ has (I think) a 10% tolerance for
> board thickness. The best way to hold down the board is by vacuum.
>
> As for the "paper" board, you want CEM type as
> opposed to the FR4. I get mine from a seller on
> Ebay
> (<http://stores.ebay.com/PCB-Laminates-Copper-Clad?_trksid=p2047675.l2563
> >).
> There are a few "autoleveling" packages that
> probe the board height before doing the isolation
> milling and these seem to work quite well. I use
> Eagle and a ULP called pcb-gcode.ulp with autoleveling to make my boards.
> For fine work, I use a 30� V bit, and for general
> non critical stuff, a 60� one from <http://www.drewtronics.net/>.
>
> HTH
> Art
> Country Bubba
>
>
> At 09:01 AM 12/13/2012, you wrote:
> >Hello,
> >
> >I am trying to mill the pcb (FR4) with a taig.
> >
> >I did not have much luck with a uniform trace isolation even when I hold
> >the board flat down by clamping down on the board edges. It appears that
> >the pcb surface might not be uniform and that might be the reason why I
> >cannot remove/mill out the copper layer consistently. I read about using a
> >foot (http://hackaday.com/2011/04/22/pcb-milling-tutorial/) to push the
> pcb
> >down while milling, but, that was a bit too much for my skill level.
> >
> >I read somewhere that it is easier to just paint the whole circuit board
> >with some paint and then remove/scribe the paint off wherever the traces
> >were being milled. This process is described here:
> >http://reprap.org/wiki/Scratch_n%27_Etch_PCBs . Just wanted to check if
> >anyone has experience with this?
> >
> >On a different note, I read that "paper phenolic" boards are better/easier
> >on the mill and drill bits. I checked digikey and mouser and could not
> come
> >up with any "paper phenolic" boards. Wondering if anyone knows of a
> >supplier for "paper phenolic" boards?
> >
> >I used the EM2E8-0625-90VC bit from
> >http://www.precisebits.com/products/carbidebits/scoreengrave.asp to mill
> >the board. Maybe, I need to use a 45 degree bit as noted in this article:
> >
> http://millpcbs.com/index.php?option=com_content&view=article&id=23&Itemid=47
> >
> >Any thoughts or advice, please?
> >
> >Thanks
> >Joe
>
>  
>


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