Kad nađem otvarač, otvorit ću konzervu njime.

when

Breakdown of Kad nađem otvarač, otvorit ću konzervu njime.

• htjeti: will
• otvoriti: to open
• naći: to find

Questions & Answers about Kad nađem otvarač, otvorit ću konzervu njime.

Why is nađem in the present tense if the sentence is talking about the future?

Because after kad meaning when, Croatian usually uses the present tense to refer to a future event.

So:

• Kad nađem otvarač = When I find the opener
• otvorit ću konzervu = I will open the can

This is very similar to English, where we also say:

• When I find it, I’ll open the can
• not normally When I will find it...

In Croatian, nađem is the present tense of the perfective verb naći, and here it means a future completed action: when I have found / once I find.

Why can’t I say Kad ću naći otvarač...?

Because in Croatian, after time conjunctions like kad meaning when, you normally do not use the future tense to express a future time clause.

So:

• Kad nađem otvarač, otvorit ću konzervu. = correct
• Kad ću naći otvarač... = not right in this meaning

Kad ću naći otvarač? would work only as a separate question meaning:

• When will I find the opener?

So the issue is not that ću naći is wrong in general, but that it is wrong inside this kind of when-clause.