[peteeng]

Hi Dam - To calculate the max tension in the belt we need to know the acceleration of the weight. Does this occur over 50mm? 20mm? This acceleration will determine the forces not the speed. Then the least accel would be over 200mm so it speeds up to halfway then slows down to the end. It reverses and repeats. The average speed would be half the max speed. Will this run 24hrs a day?

2 secs cycle = 1,000,000x2=2M sec 2M/60/60= 556hrs = 23days so a 20sec cycle would be 230days ? what sort of cycle time are you aiming at???? What does it do? Does it make milk shakes? Peter

If I were making such a rig I'd use a crank not a belt and pulley.... much easier. Whats the pitch of the screw? Vibration is in the lead screw not in the belt. Long screws vibrate but a short screw like this probably would not vibrate. Whats the diameter of the screw? Also need to know the inertia of the motor, do you have the motor spec? The motr needs to accelrate itself, the screw and the mass. Often the motor and screw are the highest inertial loads in such a system....

[damunk]

Hi Dam - To calculate the max tension in the belt we need to know the acceleration of the weight. Does this occur over 50mm? 20mm? This acceleration will determine the forces not the speed. Then the least accel would be over 200mm so it speeds up to halfway then slows down to the end. It reverses and repeats. The average speed would be half the max speed. Will this run 24hrs a day?

2 secs cycle = 1,000,000x2=2M sec 2M/60/60= 556hrs = 23days so a 20sec cycle would be 230days ? what sort of cycle time are you aiming at???? What does it do? Does it make milk shakes? Peter

If I were making such a rig I'd use a crank not a belt and pulley.... much easier. Whats the pitch of the screw? Vibration is in the lead screw not in the belt. Long screws vibrate but a short screw like this probably would not vibrate. Whats the diameter of the screw? Also need to know the inertia of the motor, do you have the motor spec? The motr needs to accelrate itself, the screw and the mass. Often the motor and screw are the highest inertial loads in such a system....

The max speed is 0.4Mper second and there is hardley any viberation in the leadscrew that is 25mm thick. short lead screw so that is a bonus.
the acceleration is instant. 400mm/s instant acceleration but not all the time. only when required.

probably only run a few hours a day. I just read on cam belts for cars and they are around 1200-1400N tensile strength and similar thickness to my belt 2-3mm toothed belts.
you woudl think the forces in a car engine on a belt are alot more than 40kg going in either direction .

[Mooser]

.... If I were making such a rig I'd use a crank not a belt and pulley.... much easier.

Could you elaborate on this crank idea a bit?
I've got a similar kind of thing going on, lifting a 15kg weight with a ball screw / linear guides. Distance is 700mm and the speed needed is comical. Right now as the motor is maxed out at 1000rpm, 4mm pitch ball screw so and I was going to see about using a timing belt and set of cogs to maybe do a 3:1 or 4:1 to the screw instead of just a straight drive and stumbled across this thread.

Just not really getting my head around the crank idea

Thanks