|
|
Post by bLouChip on Aug 12, 2024 12:10:23 GMT
I use my MegaV gen1 XL machine for milling, plasma, and laser process. I'm considering the purchase of a diode laser head with a 0.045mm square dot size and capable of 635 DPI.
In stock configuration, MegaV gen1 XY motor drivers are setup at 3200 pulses/revolution, and grbl config of 57.chg STEPs/mm, making 1 STEP = 0.0175mm of axis linear vector, but as much as 0.0245mm of XY vector. I'd prefer more than 2 to 3 STEPs per dot, and if I were to do this, I'd leave it setup in this XY doubled resolution config for all 3 processes. So here's my question:
How much of the 270oz-in torque (most important for milling) am I giving up if I were to tweak the drivers to 6400 pulses/revolution, and grbl to 114.chg STEPs/mm, thus doubling the STEPs / mm resolution. And are there other negative effects such as max speed reduction (currently 16,000 mm/min) ?
Most of the NEMA 23 motor specs and torque curves that I find on the internet that are associated with a picture of the motor show a different physical motor profile than those on the MegaV, the MegaV having taller profile motors. So I don't trust those internet specs. I also recall Derek mentioning once that MR steppers were made to custom specs.
|
|
|
|
Post by btreichel on Aug 13, 2024 4:30:13 GMT
With power at a max constant, double the speed = 1/2 the torque. But there are also things like speed torque curves to consider, and efficiency maps. Plus lower efficiency equals more heat.
|
|
|
|
Post by bLouChip on Aug 13, 2024 12:50:32 GMT
btreichel, agreed on all your points. and that's what typical motor power curves are usually about.
To clarify my case, I'm not looking for more speed as in linear motion speed if that is what you meant, rather I'm considering doubling STEPs/mm, which is a function of resolution and accuracy, within the bounds of gearing precision of course, but also within the bounds of stepper motor physical construction and driver circuit specifications.
The information for MillRight's MegaV steppers I don't believe is available on the internet, I believe they are custom built. The drivers have specs printed on the side which suggest they can finesse a bipolar stepper 1/6400th of a revolution, but can the motor respond to that pulse ? If so, then with sufficient torque to drive the heavy MegaV plus the milling load and speeds that we're use to ? 1/6400 of rev = 0.009mm linear distance on MegaV XY axes, which is doubling the STEPs/mm of the stock configuration.
|
|
|
|
Post by btreichel on Aug 14, 2024 4:19:39 GMT
If you are not looking to increase speed but just the number of steps per distance traveled it should be possible. Sounds like a recalibration of the system. I'd try to get a conversation with MR support to find out any possible problems. If something is hard coded to 'steps per distance' then there could be a problem. The number of pulses per time period could be an issue, but that limit should only reduce actuation speed.
|
|
