Both AE and BC has a wooden gear with the same recipe, but this still different items and one cannot be replaced by other. I cannot craft BC's wooden gear for BC's machines and I cannot use AE's gear in BC's recipes. http://imgur.com/ka9re0K

I assume that you turned on Duplicate Items? cause the gear is a duplicate item?

Even with DuplicateItems=true I cannot upgrade wooden gear to stone gear and use wooden gear for creating redstone engine from BC.

If its false, it won't exist in first place, BC is not comparable with ae2s items

I have nothing against the incompatibility between AE and BC items, but with AE I cannot craft almost every BC's machine because its require BC's gear, which not craftable.

Ok, maybe this conversation will make more sense with the following, did you start with DuplicateItems on or off? and did this start with rv1.alpha build 34, or an earlier build?

EIther way try Build rv1 35 I re-did the entire system that is responsible for preventing this.

Yeah, rv1 35 seems to be fine, you can close this.

Close.