In response to Paul Bellamy's enquiry, I use a modern plastic belt
which comes under the trade name 'Redthane Belting' and is available
from any competent driveline supplier, of which you should find a few
in any industrial city. Whilst I am generally a purist when it comes
to restoration, I use this in preference to round leather belting since
it is very easy to fit and adjust. It is, in effect, a hollow tube
and joined by the use of a 'widget' inserted into the hollow middle.
This widget is a short aluminium ( called aluminum in USA! ) rod with
sharp barbs which cut into the plastic and resist any usual tension.
It is the ideal solution to most belting needs where, for example, it
is not easy to effect an adjustment of axle spacing or the pulley
section is not suitable for standard V belts.
The smallest I have used was about 3/16 inch diameter, for replacing
the two belts in my Pell 25 street organ, and the largest was 3/8 inch
diameter for the 1/4 HP driveline on my recently restored Frati piano
orchestrion. In all applications I have never had any breakages.