I’d like to add another option for your heat sealing. I use a commercial hot plate and some “irons” in various sizes to make my welds. The hot plate is pretty simple and can maintain a steady heat of about 240 degrees. The irons are home made with aluminum square stock cut to different lengths from 3/4″ to 3″ affixed to cedar blocks with JB weld. The square stock is in 1/2″ to 3/4″ wide (just under the 7/8″ belt size.
I let the blocks heat on the hot plate and use them to heat the welding length, return the block to the hot plate and use a cold aluminum plate heat sink to press the weld and set the weld by reducing the temp of the fabric. The weld takes about three seconds of contact to do the job on a flat surface. On a arch you need to roll the iron over the arch in a slow process to heat the fabric enough for the weld.
After we finish the welding of the belts we go over them one more time laying flat to finish off the ruffles on the edges and make sure we have a full weld seal across the belt. You can also iron out ridges if necessary in your belts.
Mike