Solsylva, Subst. belt with motor

[SCHootie]

I'm building the dual lead screw motor and I am overthinking it like I always do things, plus my order form sdp-si seems to be slow in getting processed. How would it be to use two motors vs. the belt set up? The cost of the belt and three drive pulleys costs about $55 vs $40 for a motor. I'm building out of metal so I planned on using bigger motors than what the plans called for, but this means I may need more expensive drives to reap the benefits. Would a smaller motor(two ~200oz motors) on each screw equal one ~425 oz motor driving the belt and two pulley. Does this cause problems trying to synch the motors.

[CNCkitsandBITS]

I’m not a mechanical engineer but I would say having two motors with half the power will not be equal to one using pulleys and a belt.

While you are cutting in the centre of your X axis you will get the full torque of both motors but when it comes to cutting off centre the loads on the stepper will change. One stepper will be pushing or pulling the gantry while the other will just be maintaining the position of the other side.

With a pulley and belt system the power will go where it is needed. Say you are cutting at one side of your X axis 95% of the force required is going through that sides screw and only 5% will be needed in the screw at the opposite side (to maintain the position of the gantry only).

I look at it this way; take a pole and hold it with both hands spread wide apart then get some one to grasp the pole close to one hand and pull. Most of the power to resist the pulling will go through one arm; the other will just keep the pole level. Now have the pole pulled at the centre, both arms are now equally pulling against the opposing force.

Like I said I am not an engineer and would be interested to know if I am talking complete rubbish but that’s the way I see it.

John