Homebrew PCBs

> As soon as you need to compensate something isn't right ;-)

What is the lead accuracy of the best ball screw you can find? What is 
the typical diameter of a homebrew PCB pad? What is the hole diameter 
in that typical pad? Truth is, you won't even have to compensate for 10 
thou backlash unless aesthetically dead center means a lot to you.

> 10mil in a foam cutter is probably below what you consider too much.

I'm willing to bet the farm (if I had one) that more than 50% of all 
industrial CNC setups have backlash > 10 thou. Either because greater 
accuracy was never required or due to lack of maintenance. Whatever, 
provided the end product isn't being impacted, nobody cares. Search 
Google on >milling backlash thou< to get a better feel of what is 
tolerated in milling circles where backlash is most important.




--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
> On Wed, 29 Jun 2005 17:36:34 +0200, derekhawkins <derekhawkins@y...>  
> wrote:
> 
> >
> > What does "work right" mean? There are tolerances in dimensions and
> > targeted positions after motion. Do you consider 10 mils of backlash
> > in a foam cutting CNC setup the result of a poor design for example?
> 
> 
> As soon as you need to compensate something isn't right ;-)
> 
> 10mil in a foam cutter is probably below what you consider too much.
> 
> ST