[shineworld]

Steppers lose magnetization with high temperatures.
Therefore, if vector drivers with encoders are not used that limit the use of the current supplied to the poles to only that which is needed, it is possible that during long machining operations over time the internal temperature of the motor will reach threshold temperatures that demagnetize the magnets losing torque and consequently steps during machining.

[Titaniumboy]

Hi TKMS - sorry you're using a compression bit which means the chip is being pushed down the hole so the chip thickness has to be small to stop the bit from choking. So a 1/8" tool from amana says 0.005" = 0.0127mm. 1/4" tool says 0.001" = 0.0254mm

So looking at feeds 40/18000/2= 0.0011" (0.028mm) which agrees with their number.

Math is a bit off.
.005” = 0.127mm
.001” = 0.254mm
.0011” = 0.28mm

[tkms002]

a 1/8 cutter shouldn't cause those motors to lose steps , the cutter should snap long before that happens

That is kinda what I thought and I have broken a number of them after using them a while. However, After switching to another bit in this pack it immediately snapped(it was running on the X axis that has 2 motors) after only going about 2 inches. A third bit from this pack is cutting with no issues.
All I can think at this point is it was the bit.

[peteeng]

Hi TKMS _ Ops thks for the correction. Peter

[metalmayhem]

All I can think at this point is it was the bit.

it's good that you've been able to narrow down the issue , the fact that a 1/8 bit can cause that sort of problem indicated a bigger problem . The 570oz motors have plenty of force with ballscrews but they are definitely lacking on your belt drive . It might be worth looking at gear reducers for the steppers , you'll lose on rapid speeds but you will gain on some needed muscle