Homebrew PCBs

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

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