PLT OF VFR ACFT ON FLT FOLLOWING WITH ATC WAS TERMINATED LATE AND ENTERED CVG CLASS B WITHOUT CLRNC.

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VFR AT 5500 FT; I REQUESTED AND WAS GRANTED FLT FOLLOWING FROM DAYTON ATC AND ASSIGNED A XPONDER DISCRETE CODE NUMBER TO SQUAWK. AS I GOT CLOSER TO CVG'S CLASS B AIRSPACE AND MY DEST (PATTERN ALT 1680 FT); I KEPT THINKING THAT THE CTLR WOULD HAND ME OFF TO CINCINNATI ANY TIME OR CANCEL RADAR SVC AS I WAS WELL INTO CINCINNATI'S ATC CTL AREA; BUT I COULD HEAR THE CTLR WAS VERY BUSY ON THE FREQ. I WANTED TO CALL HIM AS A REMINDER; BUT THERE WAS NO BREAK IN HIS OTHER COMS THAT WOULD ALLOW ME A REASONABLE OPPORTUNITY TO GET THROUGH. FINALLY; THE CTLR CALLED MY NUMBERS AND RATHER ABRUPTLY SAID; 'RADAR SVC CANCELED.' I DON'T THINK HE EVEN SAID 'SQUAWK VFR.' BY THEN I WAS AT 5500 FT AND VERY CLOSE IF NOT ALREADY IN CLASS B AIRSPACE. I IMMEDIATELY CHANGED XPONDER CODES WITH 1 PRESS OF THE VFR BUTTON TO SQUAWK 1200 AND PUSHED THE PLANE INTO A STEEP DSCNT AND TURNED L; MORE TO THE N; HOPING AND EXPECTING THAT I COULD REMAIN OUTSIDE AND GET BELOW THE AIRSPACE. UPON LNDG; THE FBO RADIOED ME TO CALL THE CVG CTLR; WHICH I DID ON MY CELL PHONE WITHIN 5 MINS OF LNDG. HE SAID THAT I HAD JUST CLIPPED OR WAS VERY NEAR THE OUTSIDE EDGE OF HIS AIRSPACE AND WANTED MY EXPLANATION. I GAVE HIM THE ABOVE INFO. IN THE 2 1/2 MIN DISCUSSION; HE ASKED IF I WAS CANCELED BY DAYTON CTR WHEN I CHANGED FREQ TO VFR; WHICH I AFFIRMED 'YES.' HE TOOK NOTE OF THE FACT THAT I INITIATED A STEEP DSCNT. I BELIEVE THIS CTLR REALIZED I WAS UNDER DAYTON'S ATC CTL AUTH; THAT I WAS CANCELED AT THE VERY LAST MIN; AND WAS LEFT WITH VIRTUALLY NO TIME TO ADJUST ALT OR DIRECTION SUFFICIENTLY. I BELIEVE THE CTLR REMARKED AT THE VERY END OF THE CALL THAT I WOULD NOT EXPECT TO HEAR ANYMORE OF THIS EVENT. CONTRIBUTING FACTORS: POSSIBLY DAYTON CTLR WAS WAY TOO BUSY TO KEEP TRACK OF MY LOCATION RELATIVE TO CINCINNATI CLASS B AIRSPACE. CORRECTIVE ACTIONS: IN THE FUTURE; I DON'T THINK I'LL REQUEST FLT FOLLOWING FOR SUCH A SHORT FLT. I HAVE FLOWN THIS RTE BEFORE AND WAS ALWAYS HANDED OFF OR CANCELED; OR WAS INSTRUCTED TO DSND WELL ENOUGH OUT AS NOT TO CAUSE PROBS.