A VFR PILOT AT A CTAF ARPT REPORTS AN UNSEEN NEAR COLLISION WITH AN IFR ACFT DEPARTING A CROSSING RWY. THE IFR PILOT DID NOT CALL A CTAF DEP BUT SAW THE REPORTER.

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I STATED OVER CTAF THAT I WAS TAXIING TO RWY 31 IN ZZZ1. A TWIN COMMANDER RPTED HE WAS ON A 1.5 MI FINAL FOR RWY 26. I ACKNOWLEDGED AND TOLD CTAF THAT I WOULD HOLD SHORT UNTIL THE COMMANDER LANDED ON RWY 26. WHEN HE CALLED CLR OF RWY; I ANNOUNCED MY DEP FROM RWY 31 ON CTAF. AS I CLBED THROUGH 500 FT A PLANE I HAD NOT YET HEARD ON CTAF CALLED AND SAID WE ALMOST HAD A COLLISION AT THE INTXN OF RWY 26 AND RWY 31. HE WAS UPSET AND TOLD ME I WOULD BE CONTACTED WHEN HE ARRIVED IN ZZZ2. THE PLT IN THE COMMANDER GOT ON CTAF AND TOLD ME HE HEARD MY ADVISORIES ON CTAF. I NEVER SAW THE PLANE I ALMOST HIT AND NEVER HEARD HIM CALL ON CTAF UNTIL AFTER THE INCIDENT. HE SAID HE WAS ON AN IFR FLT PLAN AND WAS CONFUSED WHY I WAS NOT. I THINK THE INCIDENT OCCURRED FOR A COUPLE OF REASONS. WHEN HE PICKED UP HIS IFR CLRNC HE FORGOT TO CALL CTAF OF HIS INTENTIONS. I ALSO THINK HE THOUGHT THE ARPT WAS HIS BECAUSE HE THOUGHT INCORRECTLY THAT THE FIELD WAS IFR. WHILE I COULD NOT SEE RWY 26 FROM RWY 31; I SHOULD HAVE BEEN MORE AWARE OF THE TFC AT ZZZ1.