Don't know if it's a known problem, but something you could try is to:
- print out a test pattern
- etch it to a pcb
- program it to your cnc rig.
Then:
- stick a scriber bit into the cnc rig
- start the drilling run
- measure the errors in both directions
- convert these errors to x and y percentages
With this info, you'll have two different options:
1) transform the artwork prior to printing, so it
matches the CNC
2) transform the values in the drill file, prior to
submitting it to the CNC rig, so the drilling
matches the artwork.
Given that I'm comfortable with python scripting, I'd go for option 1,
and write a python/PIL script to transform the artwork.
derekhawkins wrote:
> Hi,
>
> Just finished putting together a CNC drilling machine and have now
> stumbled on a problem that I never anticipated....The drilling machine
> appears to be more accurate than the printer used for the PCB
> artwork....Tried both a HP2420 (laser) and Epson 2200 (Inkjet) and the
> results were similar. Is this a known issue with CNC setups?
>
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> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
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--
Cheers
David