What kind of twine are you using?
For years I used waxed whipping twine that I got at West Marine. Its a bit on the thin side, but I double it before tying the knots and it has always held.
But then I noticed that Daryl Wong's bands seemed to have some sort of neat black twine, and I asked him what it was.
QUIK_KLIPS
Its # 802B Brim twine from this site, and I recently got a roll. Its wider and flatter, and I like it a lot. The down side is that a roll is a lifetime supply for most of us, and costs $40. Daryl says he ties about 1500 bands per year, so he goes through the stuff. Even though I tie bands for several friends, at about a yard per band I'm going to end up leaving most of the roll to someone in my will.
But still, its nice to use the good stuff, and I'll never have to worry about West Marine having the other stuff in stock again. And maybe you are young enough to use it up.
You probably already know how to taper the bands if you have an inclination to do so, and how to insert the wisbone knot in the rubber. But just in case anyone else reading this is curious-
To taper the band, stick a nail in the end to stiffen it, then turn it against the wheel of a bench grinder until sparks come off of the nail head.
You can insert the knot with needle nose pliers, but I tend to lose flesh and blood when I do it, especially with tapered bands. So these simple wishbone insertion tools make it a lot easier. The first one is just a stainless tube with a slot cut in the side of it. You put in a vise, pull the knot tight against the end, and stick the tubing onto it. The other one can be hand held, and is a Rob Allen tool. The tube had a pretty big flare on the end and the knot in the end of my Spectra wishbone would hide in it and come back out of the rubber when I withdrew the tool, so I just ground off most of the flare so that I could grab the knot through the rubber to hold it.
