componet package? and Eagle 5.60?

[mike_mccue]

I am beginning to learn basic CNC machining on a bench top mini mill. One of the things that is suggested as a potential project is the fabrication of prototype circuit boards using a procedure where the CNC mill is programed to etch or remove excess copper off of a fully clad board leaving only the traces that are needed for the circuit.

I stumbled upon a program named Eagle 5.60 that enables me to assemble a schematic and layout a board AND generate the G-code that is required to run the mill.

I'm learning to use Eagle but I work with old style discrete components like axial metal film resistors. The eagle program comes with lots of libraries that focus on modern form factors. Which leaves me to wade thru lots of choices looking for some simple part. Here's where I need help... I often end up with several choices that refer to the "package" description.

How can I learn what the official "package" description is of older style parts that I find familiar and have never described as such?

Thanks very much,
mike

[Steve Conner]

Eagle comes with a lot of through hole parts as well as the more modern SMTs. I've been using Eagle for commercial PCB design for about 6 years or so, and you just have to learn what's where. The package description strings are somewhat unique to Eagle, rather than being an industry standard. In the case of through-hole components, they usually just encode the distance between holes and the size of the component body, which is really all there is to a through-hole resistor or cap anyway.

If you search for components through the Control Panel > Libraries interface, instead of using "Add" in the schematic editor, then it shows you a picture of what you're going to get, and you can recognize the part you want that way.

Note that Eagle is meant to be used by laying out your schematic in the schematic editor, and then hitting "Switch to board", whereupon it dumps all the parts into the board editor with a maze of yellow "airwires" connecting them. If you try to make a board without a schematic, it gets harder. For instance, in the schematic, you can place a TL074 op-amp chip (in linear.lbr IIRC) and you get presented with a choice of DIP or SOIC. But if you start trying to place footprints on a board, there's no such guidance. I've seen people try to do it this way regardless.

Once you've found the kind of resistor, etc. that you want, and placed one, you can just use the Clone tool in the schematic editor (icon that looks like two little stick men) to get more of the same.

[mike_mccue]

Thank you Steve,
I will continue to study Eagle and everything you have explained makes sense.

My first project is going to be a small board for the LM317 "phantom power" circuit that you showed me how to layout.

I have a schematic put together in Eagle but I haven't gotten the right physical dimensions yet for the board... I just used R-US and C-US choices... and have a temporary board layout.

I don't do much of this sort of work... it seems like I should just build my own library of the typical hole thru style parts as I need.

thanks again,
mike