Francisco,

You cannot pass JDBC URL to the setDatabase(...) method. I have
suggested you to try that URL with DriverExample, where connections
are obtained from DriverManager to check, if you can access your
database with the specified parameters at all.

When using connection pool, method you have to pass the string into
the setDatabase(...) method that in your case would be:

setDatabase(maquina+"/3050:"+dir_db);

With an error "Could not obtain connection during blocking timeout"
connection pool tries to tell you that it was not able to open a
connection to your server. On the debug level driver logs the
exception, in order to enable logging you have to do the steps
described on http://jaybirdwiki.firebirdsql.org/FAQ/JayBirdLogging page.

Roman