Layers in Eagle

What layers need to be turned on before you start the process of converting it to what SparkFun wants? I know it says to turn on layers 29 30 but what else?

I think at least you want:

Top, Bottom

tStop, bStop

Pads

Vias

Dimension

tPlace

tNames

tValues

Drills

If you have bottom-mounted components , probably add bPlace, bNames, and bValues.

If you have components that require special drilling/milling, include Holes/Milling as appropriate.

If you have SMT parts, you’ll probably want tCream/bCream as appropriate (i think – i’m not too familiar with SMT parts).

If you’ve marked areas as restricted, you probably want tRestrict, bRestrict, and vRestrict.

I’m basing the above on my one PCB design and the descriptions of the layers from Build your own Printed Circuit Board by Al Williams.

I have been using

1 - Top

16 - Bottom

17 - Pads

18 - Vias

20 - Dimension

21 - tPlace

22 - bPlace

23 - tOrigins

24 - bOrigins

25 - tNames

26 - bNames

27 - tValues

28 - bValues

29 - tStop

30 - bStop

and my boards are turning out without problems.

My understanding is that tCream and the bCream stand for top Solder Cream and bottom Solder Cream. They should not be turned on since they are for specifying where you cutouts should be made in the solder paste stencil. You want to turn on the tStop and the bStop which stand for top Soldermask Stop and bottom Soldermask Stop. This will stop the soldermask from being applied to the top and bottom pads.