The answer is $8$ uses of the scale.

##First Weighing##
Take one coin away and make $4$ groups of $30$.  Pick any two of these groups and weight them.  If scale balances, then they are all good coins.  If the scale tips, then you know there is at least one bad coin in those $60$ and the other $61$ are good.  Either way, you have eliminated at least $60$ coins in one weighing leaving you with either $60$ or $61$ coins.

##Second Weighing##
WLOG, we will assume you have $61$ coins.  Take one away and split into $4$ groups of $15$.  Again, pick any two and weigh them.  You will be able to eliminate at least $30$ more coins in this way.

## Third Weighing##
You now have $30$ coins, plus one set aside, plus one in your pocket.  The one set aside may or may not have been ruled out as a possible bad coin.  Lets say that we still don't know, so that you have $31$ coins. Add your coin from your pocket to make $32$ and divide into $4$ groups of $8$.  Weigh two groups, and you will be able to eliminate $16$, leaving you with at most $16$ coins.

##Forth Weighing##
Split into $4$ groups of $4$.  Eliminate $8$ by weighing two of the groups.

##Fifth Weighing##
Split into $4$ groups of $2$.  Eliminate $4$ by weighing two of the groups.

##Sixth Weighing##
Weigh $2$ of the $4$ remaining coins.  $2$ will be eliminated.

##Seventh and Eighth Weighings##
Weigh the last $2$ coins.  If the scale balances, you are done and all coins are equal.
If the scale tips, then use your last attempt to see which one is the bad one by comparing one of them to a known good coin.
You now have only $4$ coins left.  Take $3$ of the coins and one from the pile of known good coins.  Weigh 2 on each side.