microstep uniformity

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I have just been playing with the numbers on toothed belt drives and stepper motors but I don't know if the answer I have come up with are right.
Using the formulae given in the Transdev datasheet for Syncroflex toothed belt drives, I get a figure for tooth shear strength when using a 10mm wide belt and pulleys of 16T and 40T, 6 teeth engaged, of just a tad under 200 Newtons at the stepper motor. The Tension Member is not much better at about 300 Newtons.
Although I haven't settled on a stepper motor yet, the most likely candidate, the so-called 3Nm NEMA 23s that are available at the moment, put out about 2Nm at stall - about 160 newtons at the periphery of a 16 tooth pulley.
Is toothed belt really that wimpy, or have I lost a decimal place somewhere?

Hmm, a quick edit here. Looking at the datasheet for Zapps SY60STH88-3008BF, the maximum radial load is given as 75 Newtons. I assume that if you are applying a torque of 2Nm at a 12.5mm radius then you will get something like 160 Newtons of radial force reacting to it. I may have to think a bit more about the motors as well.