Benefits of Belt Drives for Steppers

[Tool-n-Around]

.....However it looks like you've only considered torque, which is only one part of the equation.You also need to consider inertia and acceleration.

I did consider acceleration for the build and have went to lengths to make the trades to minimize moving mass while maintaining rigidity for my work envelop. I just didn't delve into it in this post because I viewed any differences in total moving mass due to motor selection to be a small factor in total system mass/inertia, so for the most part, system mass decisions were independent of motor selection other than selecting motor size/power of course. Value for money was another trade that landed me on closed loop NEMA34 steppers, as opposed to the next step to servos.

These things aside, for any given speed, the reliably acheivable acceleration is a very strong function of motor torque. I found that most motor manufacture's rule of thumb was keeping system inertia <10x that of motor rotor inertia, and in some cases for very high speed system the recommendation was <4x. In the end, it's an easily tunable parameter and unless your average tool path lengths are very short, you don't pay much of a price in run time for backing off a little on acceleration.

I studied a lot builds here and elsewhere as they relate to my machne build and was going to start a build thread but I dont think there is anything particularly novel about the design I settled on, and chose to focus more on the construction methods to optimize the mass/rigidity trades.

Thanks for the post,

Best,
Kelly

[Lee Roberts]

I studied a lot builds here and elsewhere as they relate to my machne build and was going to start a build thread but I dont think there is anything particularly novel about the design I settled on, and chose to focus more on the construction methods to optimize the mass/rigidity trades.

Hi Kelly welcome to the forum, this is exactly why you should share/start a build log, your design doesn't have to be novel but it will be interesting to allot of us, we can focus on the construction aspects together and maybe learn from each other too :)

Are you building a moving gantry type machine or mill?

MACHINES
Discussion related to machines, working with them and building your own.

[Tool-n-Around]

Are you building a moving gantry type machine or mill?.

Gantry. Considered Moving and Fixed Gantry, and Moving Table, but moving gantry seemed to best fit my goals.

Hi Kelly welcome to the forum, this is exactly why you should share/start a build log, your design doesn't have to be novel but it will be interesting to allot of us, we can focus on the construction aspects together and maybe learn from each other too :).

I'll see what I can do but am pretty far along. The Z is built. Most of the linear motion components are in hand or on order and design fairly well committed. Motors, drives, machine controller not yet committed but fairly far along yet I must confess, still learning.and plenty of room for learning and input there. Here's teaser on the Z.



Best,
Kelly

[Robin Hewitt]

I always use belt reductions to get 5um per half step, tuck the motors out of the way and keep the hand wheels. I round every movement out to 0.005mm. Works for me.
Thing is my latest mill conversion has steppers and DRO's. Not a problem unless the stepper controller can read the DRO's. I couldn't resist...
What will I have it do when the motor disagrees with the DRO by >0.01?