Homebrew PCBs

Even a metric leadscrew should not be a problem.

Consider a coarse leadscrew of 16mm-2mm.  (not sure of the exact 
thread numbering) Here in the States, we call it All-Thread, or 
threaded rod, but basically it is just a long shaft that is fully 
threaded.

200 steps per revolution will spin a 2mm leadscrew with 2540 steps 
per inch or an theoretical accuracy of 0.0003937 inches.

a typical IC has pins that are 0.2 inches apart with a drill hole of 
about 1mm, and that has plenty of room.  having that hole within 
0.0003937 inches or within 0.01mm is close enough for even the most 
demanding home brew.

a half step drive will cut that in half and a 10x microstepper will 
locate holes within 0.001mm and that is close enough for a 
professional shop !

I'm not sure what the metric timing belt pullys can offer, but they 
do offer rations that will increase that accurcy even more.

please feel free to correct my math.  conversions are not my strong 
point.

Dave


--- In Homebrew_PCBs@yahoogroups.com, Stuart Winsor 
<stuartwinsor@a...> wrote:
> In article <blpk30+hmb@e...>,
>    crankorgan <john@k...> wrote:
> > The parts I use are only found in US and Canada. Other countries 
use 
> > metric bolts. This throws the design way off!
> 
> Not entirely true. Here in the uk non-metric fasteners, taps, dies, 
drills
> etc are still readily available. :-)
> 
> I still use BA for all my electronics construction and the lead 
screws for
> my homebrew pcb drill jig are 1/4" Whitworth. This thread has a 
pitch of
> 0.05"
> 
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