Well, the belt failed today. But not for the reason i thought it would.
The tape is plenty strong enough. Where I doubled the tape thickness it made such a whack whack as it went round, that the sanding belt rucked up on the double thickness against the wood.
I have the MK2 version glued as i type. This one will only have a single layer of tape, but as its only 50mm tape and a 100mm belt, i shall use two pieces of tape, and make them longer than the last, and staggered, again to offset that "whack" as the extra thickness comes over the roll, and some superglue on the butt join on the grit side to stop any flap developing.
I emphasise this is an exercise to get me out of trouble if a belt breaks or wears out unexpectedly. I get a few visitors from the UK during the year, and they are always expected to bring care packages for me, but they can be a month or more apart. I dont think this will be the full answer to my store problem. but as always, its fun trying.