How to fill the spread sheet ? #EQ3


laurent.bergougnoux@...
 

Hello,
i try to fill in the spreadsheet for en EQ 3.2.
I brought NEMA 17 motor 400 step (0.9° angle), GT2 (20:40 for RA ans 20:60 for DEC)

I have some questions :
what is DRIVER_MICROSTEPS ?
GR2 AXIS1 : i write 2  GR2 AXIS2 : i write 3 Is-it OK ?
GR1 i don't know how to write here. The tooth number of the internal eq 3 RA and DEC ?

Thank you for you answers.
--
Telescope 150/750 Mount EQ3.2
France


Howard Dutton
 
Edited

On Mon, Aug 2, 2021 at 05:54 AM, <laurent.bergougnoux@...> wrote:
i try to fill in the spreadsheet for en EQ 3.2.
I brought NEMA 17 motor 400 step (0.9° angle), GT2 (20:40 for RA ans 20:60 for DEC)

I have some questions :
what is DRIVER_MICROSTEPS ?
GR2 AXIS1 : i write 2  GR2 AXIS2 : i write 3 Is-it OK ?
GR1 i don't know how to write here. The tooth number of the internal eq 3 RA and DEC ?
GR1 is the timing belt or spur gear reduction between the motor and worm/gear.
GR2 is the worm gear.

RA
  GR1 would be 40/20 = 2 (for 2:1 reduction ratio, smaller pulley on the motor.)
  GR2 would be 130 (130:1 reduction ratio, 130 tooth wheel gear)
Dec
  GR1 would be 60/20 = 3 (for 3:1 reduction ratio, smaller pulley on the motor.)
  GR2 would be 65 (65:1 reduction ratio, 65 tooth wheel gear)

Total RA reduction ratio 260:1 and total Dec 195:1.

These EQ3-2 mounts are marginal for conversion to goto, though it has been done.


Dave Schwartz
 

DRIVER_MICROSTEPS is the electrical trick that the driver modules use to position the stepper at locations between the native full-step locations (those you see when turning the motor by hand with the power off). It will typically result in smoother motion with finer resolution although the accuracy is not always precise. it is almost always a power of 2 i.e. 2, 4, 8, 16, 32, 64, 128, 256 although some of the less expansive driver modules will not implement some of the higher numbers. This is usually the last thing you adjust after you finish entering the fixed quantities related to the mechanicals you have. You would adjust the microstep to bring the STEPS_PER_DEGREE number into a range suitable for what you wish to do.

Here's a good reference on microstepping https://hackaday.com/2016/08/29/how-accurate-is-microstepping-really/

GR2 is usually the final stage of reduction... the worm gear ratio for EQ mounts or the last (large) pulley for ALT/AZ mounts. GR1 is usually all the mechanical gear reduction between the final stage in GR2 and the motor itself, not including microsteps.

On an EQ3.2 mount the final (worm) gear ratio (GR2) is usually 130 for RA and 65 for DEC (reference: https://www.astroeq.co.uk/tutorials.php?link=ratios) Your GR1 values are as you calculated for the pulley reduction stage: 2 for RA and 3 for DEC.

On 2021-08-02 1:00 a.m., laurent.bergougnoux@gmail.com wrote:
Hello,
i try to fill in the spreadsheet for en EQ 3.2.
I brought NEMA 17 motor 400 step (0.9° angle), GT2 (20:40 for RA ans 20:60 for DEC)

I have some questions :
what is DRIVER_MICROSTEPS ?
GR2 AXIS1 : i write 2  GR2 AXIS2 : i write 3 Is-it OK ?
GR1 i don't know how to write here. The tooth number of the internal eq 3 RA and DEC ?

Thank you for you answers.
--
Telescope 150/750 Mount EQ3.2
France


laurent.bergougnoux@...
 

Thank You Dave
--
Telescope 150/750 Mount EQ3.2


laurent.bergougnoux@...
 

Thank you Howard
--
Telescope 150/750 Mount EQ3.2