[Coco] Little Johns 8 slot MPI

[Mark J. Blair]

On Sep 21, 2013, at 09:58 , Gene Heskett <gheskett at wdtv.com> wrote:
> But when loaded into eagle, I find the .brd is 6.05" wide front to back and 
> I would need about 1.5" more Y axis travel than my mill has.  So, short of 
> building a new machine, which I might not have time to finish, I can't make 
> it.

Maybe it would make more economic sense to fabricate the board at a quick-turn PCB house like PCBexpress, APcircuits, OshPark, etc? I haven't examined the design files for this MPI, but if you're talking about milling a PCB then I presume it's just 1 or 2 layers.

On the other hand, if you want to use this project to justify building a bigger CNC mill, then I'll helpfully point out that it would be fiscally irresponsible to NOT set up a mill to build this board at home. :)


> The $650 model is big enough, but has 2 start trapezoidal screws, whatever 
> that means, I think 2 threads per revolution of the screw.

Yes, that's what "2 start" generally means on a screw. If the screw pitch looks like, say, 10 TPI but it's 2-start, then the nut will advance as if it was a 5 TPI screw.


> I can't justify it, but I'm still thinking. ;-)

I've found that with sufficient thought, I can justify *anything*! :)

-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/