4pcb.com put a hold on my second order from them, asking for an extra $50 (bringing the cost up to $100.30) for the new board, because there were multiple images.
I asked them on the phone what the rule was now for defining multiple images. Although they did not give an exact algorithm, basically they are looking for separate pieces unconnected by copper traces. I suspect that they either do a quick look at the board manually or have some very crude program to detect probable repeats.
They are not looking just for exact repeats (which is the rule that Gabriel Elkaim told me they used), but anything that looks like multiple boards. Now I have to decide whether to pay the $50 surcharge, find another vendor, or redesign the board.
For the tiny breakout boards I may be better off with a BatchPCB.com order, at $2.50/sq in + $10 setup. I had 3 (slightly different) copies of the hexmotor 2.3 board, plus 2 each of 3 different breakout board designs for the pressure sensor.
The areas and prices for the boards (not including shipping) are
|pressure 1.3||0.7″ × 1.45″||1.015 sq in||$15.08 for 2|
|pressure 1.4||1.5″ × 1.0″||1.5 sq in||$17.50 for 2|
|pressure 1.5||0.475″ × 0.8″||0.38 sq in||$15.00 for 2|
|hexmotor 2.3||3.95″ × 3.15″||12.44 sq in||$41.11 for 1, $103.32 for 3|
|combined||7.537″ × 6.737″||50.78 sq in||$136.94 for 1|
So if I keep the original order, I’m better off with 4pcb.com pricing, but if I get only 1 motor controller board, I could reduce the price to about $75+shipping (with a new combined board, to avoid the repeated $10 setup). If I just want the breakout boards, I could do all of them without the hexmotor board as 2 copies of a combined 1″ × 3.825″ board for $29.13+shipping.
UPDATE: I decided I want the new features of the hexmotor 2.3 board enough to spend the extra $60 rather than just using the old hexmotor 1.3 board. When I want tiny boards, though, I’ll try BatchPCB.com, which will be cheaper for boards smaller than about 13 square inches (depending on shipping and how many are ordered).