Precisely drawing component footprints in EAGLE

Whats the recommended way for placing components accurately and quickly when creating EAGLE parts?

For example in the drawing below, using grids with 0.01 grids will give us the control needed for components with separation such as 10.16 but scrolling 1000 0.01 grid spaces is quite tedious.

• Using the alt grid for finer placement is not what you're looking for? – EwokNightmares Jun 8 '15 at 18:49

Use the move command.

Select the pad, via, or part you want to move. Type move (> x y), where x and y are the absolute coordinates you want the part to be moved to.

The most difficult part is choosing an origin on your part. It can be anywhere, but for your linked part I would probably use pin 1 as 0,0. Then make pin 2, select it and type move (> 0, 10.16), then pin 3 will be 10.16+5.08 for the y coordinate (Eagle unfortunately does not accept basic math inputs).

Recognize the (most common) common denominator.

If you set your grid to 5.08 things will be even easier. Then you can place pin 1, copy from it to make pin 2 and move up by two grid positions. Pin 3 is one more. Pin 7 is seven across, pin 6 is one up from that, etc. Things will continue to move in grid increments, so using the move command to move pin 10 down by 3.68, then drag it over by one grid tick, copy it and move five over for pin 9, etc.

• How do you tell whether the layout is for you looking down at the top of the device or looking upwards from the bottom of the device? – Nyxynyx Jun 8 '15 at 22:14
• That data sheet is particularly awful because the only unit mentioned is inches, but for the dimensions on the diagram to match the overall dimensions, the diagram must be in mm. Top view vs bottom view is not obvious either. Usually both bits of information are clearly listed. – Samuel Jun 8 '15 at 22:23

Don't try to snap to any particular "round" numbers of a grid when defining parts. Use the datasheet to compute the coordinates of the various corners of pads, polygons, and the like. The grid then only decides what units you use. It's often useful to switch quickly between mm and mil, depending on how the part is defined, so I have function keys set up for exactly that.

Defining a part is NOT something that should be done visually.

When in mils, I use three decimal places, and two or sometimes one for mm.

• Worth noting that in Eagle you can actually just write the units you want to use after the numerical value without switching the grid. For instance with a mm grid you can write '(1mil 25mil)' and it'll place the part at (0.0254mm, 0.635mm). But, it may be easier to simply switch the grid like you do as needing to switch back and forth between units isn't that common. – Samuel Jun 8 '15 at 23:14