Shred? No. I greatly doubt that. They will not even stretch. However this is assuming you use square supported rails, align them precisely using precision square and straight edge and don't intend to use the machine for deep routing or aluminum every day.

I have belt driven small machine with AT5 steel belts 10mm and to tell you the truth the belts are its smallest problem . I have 0.8kw spindle and i go 6mm deep with 6mm tool in wood and whatever material. Aluminum i don't do, but this due to the V bearings, not the belts.

If you are not very aggressive with speeds and feeds + use sharp cutters i don't see a problem even with bigger spindle.



But now lets step back. Why 4.5 Nm steppers? Most used steppers here on forum are low inductance SY60STH86-3008B Nema 23 Stepper motor.


At the end it greatly depends on what you want to invest in the whole machine. If you make a cheap build aimed for wood, go for it. If you will make a heavy gantry and spend money on all else. Then why cripple the machine with 10mm belts.

It would be wise though to make all so, that later could fit 25mm belts if needed.