Difficulty in repairing a bonded 5mm green polyurethane drive belt

I have been using a 5mm diameter round drive belt on my small bench drill made up from a length of green polyurethane drive belting with the ends bonded together in the usual way using the hot plate technique. After giving some 10 years of good service the original joint has now failed but I am having great difficulty in repeating the technique on the same length of belting hopefully to give a new (but shorter) drive belt but happily of a length which can be accommodated in the current set-up.

I am just wondering if this could be a problem with aging of the polyurethane over the 10 years of use because I never seem to have any difficulty when working with a length of new belting material. I would be interested to hear other people’s views on the matter as failing a solution of the problem I will have to resort to buying in a new stock of belting.

Most plastics do degrade with time so it is quite likely you are right about the possible cause of the problem.

I must say that in that 10 years it has given you good and faithful service! Be kind to the drill too, and treat it to a new belt good for another decade.

Have you cut back the ends of the failed belt? You need to make the join with "fresh" plastic - even if it is a decade old. Trying to re-bond an old joint will fail.

I have had the same problem with the drive belt for the UPT in the end bought a new length and it joined perfectly. So its possibly an age thing. Out of interest the belt did nearly 20 years!!!