Recommended CAM Settings

[Dobbs]

Hi All,

After a recent PCB manufacture problem that was tracked down to the photo plotter settings I was using, I'd appreciate (for peace of mind) if you could recommend the CAM settings that should be used for all file types (photo plotter, NC drill) or is there a standard I can refer to.

I'm using PADS PowerPCB.

Apologies if this question has been asked before, but I didn't see anything similiar in the various forums.

I've all posted this request in the PADS forum.

Thanks.

[Smelter]

Your question begs a couple more questions.
1) Can you change the output format from your CAD package?
The package I use is virtually hard coded and involves text editing a config file.
2) Are you supplying a "ReadMe_spec.txt" plain ascii file with each job that details the format for each file type you are supplying?

The "ReadMe" files I supply, always contain the following :-

Gerber files are to the standard RS-274X format
(Implied integer places = 4. Implied integer fractions = 4)

Drill files are to the standard Excellon 2 format
Trailing Zeros suppressed, Absolute, Imperial
(Digits = 2 Integer, 4 Decimal)

Mill files are to the standard Excellon 2 format
Trailing Zeros suppressed, Absolute, Imperial
(Digits = 3 Integer, 4 Decimal)


Hope this helps.

[drew3rdof3]

Howdy,

I disagree with each output being formatted differently. Mostly because I have never found a readme file with the data explaining the formatting.

When reviewing someone else's data, the drill and gerber sometimes do not match and that creates unnecessary work for me. Especially since I have never known anyone other than myself (that is, up until today :O) to include all of the formatting data in a text file. Keep the format, units, suppression, and origin the same if at all possible *and* put this in plus as much info as possible into the readme file. This practice is not for the board house as any reputable manufacturer can handle the sloppy differences. It's for the designer who does the next spin or reviews the layout.

Personally, I do RS-274X @ 2:5, inches, leading, relative. For everything. The "5" solves any round off errors even by the worst gerber viewer. I also don't believe anyone will manufacture a PCB even close to 8' any time soon. The real reason is that it's just plain easy for me.

Note that I would not object to switching to metric units if asked.

Cheers!
Drew

[Skip Yutkus]

The 2.4 trailing suppressed, English, absolute - many, many, years ago was the default Excellon drill machine format - back then that's what the board shop/driller wanted - it still persists to this day, even though machines now can accept any format - as for everything matching, no problem there, all CAM software now autodetect formats anyway, it would be highly unusual for a boardshop to make a mistake because of format - a change of 1 decimal or metric/inch is obvious - using RS274D with an aperture list is still the weakest link and should be avoided.

Skip