Homebrew PCBs

I do not use eagle, but i do the following:

My library parts have the diameters i want to use set correctly already,  
usually, because i drew them.
Then, when making the layout, i will again check them and change if i  
notice something i want different than it is in the library.

Next i will generate the gerber files. This also generates Excellon .tool  
and .drill file. The tool file contains a list of the used drills, the  
diameters, and the number of holes for each tool. The .drill file contains  
coordinates for the holes, which tool to use, and i believe a list of  
diameters at the beginning (not metric plaintext diameters, some other  
format). When i notice something amiss in the tool list i go back and  
change it in the layout, then generate the files again. I don't change the  
files directly, and i don't usually look at the .drill file at all 'cause  
the size is not plaintext and coordinates are incompatible with my brain.


I do not worry about the plating thickness, because i usually make quite  
large holes that can easily tolerate the difference, because i want it  
easy to insert components.

I hope i made it clear, i don't edit those files, i always change the  
diameters in the layout. That's basically the main point i'm making.

Since i make all my own boards myself i do not usually care about drill  
diameter at all, it is only if i have to make gerber files for someone  
that i need to make sure the diameters are correct.

ST


On Tue, 10 Jan 2006 17:48:10 +0100, scratch_6057 <dml.empsrch@...>  
wrote:

> I hope I'm presenting this question in a manner in which it can be
>
> understood.
>
>
> My question is in regard to Gerber File creation in order to send
>
> files to a PC Board Fabrication house for a number of PCBs to be
>
> produced.
>
>
> After the board layout is completed in Eagle, I run the Drillcfg.ulp
>
> file to generate a tool (drill) size report (filename.drl). I also
>
> run drillinfo.ulp so that I can have a listing of what library
>
> components create which drill hole size. I can then cross
>
> check the (component) library generated hole size against my "real
>
> world" component lead sizes, and determine what "real world"
>
> components  have lead sizes which do not match the drill sizes of the
>
> intended PC board fabrication house.
>
>
> I am ASSUMING if I find "real world" component leads, which do not
>
> closely match the board house's hole sizes ( hole size 4 to 6 mils
>
> over the component lead diameter ) I should edit the "filename.drl"
>
> so that the hole size for the component is equal to an available
>
> drill size,  4 to 6 mils larger than actual component lead size.
>
>
> The editing of the "filename.drl" should occur before any further
>
> Gerber File processing?
>
>
> I have spoken to a couple of people, who say that they do not perform
>
> any editing they just rely on the board house to provide PTH with the
>
> correct finished hole sizes. I thought I would ask this group before
>
> proceeding, as anything resulting in unusable boards would result in
>
> money I can not afford to loose.
>
>
> Please reply with reply with your experiences, thoughts, or
>
> corrections to my reasoning.
>
>
> Thanks