[met4life]

Kind of an odd question and I'm not really sure if I'm explaining it right but does anyone know the weight "limit" to these motors? Like how heavy of a gantry would be too much for one of these motors to push.

I'm really confused on how I should calculate this, like would it just be the amount of torque required to spin the threaded rod through the nut that's attached to the axis or would it be the entire weight of the axis it's moving?

I hope this isn't a dumb question but some help is really appreciated.

Thanks,
Jason

[ger21]

Unfortunately, it's much more complicated than you think.
First, the method you're using to move the machine is part of the equation. A 10tpi screw can move much more weight than a 1tpi screw, as it has much more mechanical advantage.
Second, and possibly more important, is how fast you want to move, and how quickly you want to accelerate.
Steppers lose torque as rpm's increase, so you'll likely find that you can move a lot more weight at slower speeds than you can at high speeds.
Acceleration needs the most torque, and you need constant torque during acceleration. So whatever torque you have at the maximum rpm you'll be spinning the motor is the torque you'll be able to accelerate with.

[met4life]

A part of me felt like I was missing a large portion of such an equation and your points make a lot more sense after reading them. I will be using a 1/2"-10 single start acme threaded rod and the G540 kit for the electronics.

This worry came about because I expanded the size of the JGRO by about 6 inches and seeing how big it looks after cutting the pieces for the gantry, I did some weight calculations and started questioning the motors ability to move the gantry.

The one question I couldn't answer is the speed, I have an idea of what I could achieve but I'm not sure what a realistic number would be since this is my first build. Based on the rhinocam's estimated time to cut out some stuff, I figure 60-80 ipm will be enough to satisfy me.

[ger21]

380 oz motors are really more than you need with 1/2-10 acme.
1/2-10 is really not a good choice, but it's cheap. To get any speed out of it requires high stepper rpm, which usually means lower torque.
Generally, the fastest you can expect to run with 1/2-10 acme is between 70-100ipm.
A much better choice would be 1/2-8 2 start acme, which will let you get closer to 200ipm, but it will cost considerably more than 1/2-10.

[met4life]

I won't lie, I chose to go with the 1/2-10 1 start because of it's cheap cost. From all I've read though, I've already decided that will be my first upgrade. We'll see how the performance is in the end. That upgrade may happen sooner, but thank you for clarifying that stuff with me.

I've found this DIY forum to be the best place to browse. I love seeing all the different build threads, I'll have to start mine up in the next week or two to share my progress as well.

Thanks again Gerry, I really appreciate it.