G11 Dual Axis & G8 Single Axis Configration #configuration


 

Hi Everyone 
 
Am learning how to get the correct configuration on this G11 Dual Axis and G8 Single Axis .
 
G11 using MINIPCB2 + SHC / TMC5160 / 360° Final Gear / 0.9° Motor ( OnStep-release-4.1 )
G8 using BluePill /  TMC5160 /  180° Final Gear / Original 150:1 Gear Eeduction Motor ( OnStep-release-3.16 )
 
Question:
1. how to calculate GR1 with gear-box reduction 150:1 and final is GR1 180° per rotation.
2. AXIS1_STEPS_PER_WORMROT calculation is from Stepper-Steps * MICROSTEPS ?
3. SLEW_RATE_BASE_DESIRED can self adjust °/s  ? , will it effect any accuracy?


andrea tasselli
 

1. GR1 is the gearbox/pulleys reduction ratio: in your case 150
2. Yes
3 OnStep will try to achieve the desired speed but this can be modified as explained in the text to the side.No that won't affect the accuracy.


 

From my G8 single Axis,  if i put GR1 150 and GR2 180 the step calculation will over the limit of <= 61200  will it be fine?

 

 

    Stepper-Steps MICROSTEPS GR1 GR2 (Final stage)
AXIS1_STEPS_PER_DEGREE 1920000.00000 400 64 150 180 RA


Dave Schwartz
 

It probably will not work. That is beyond the range OnStep can support properly. It is telling you that with the very high ratio in that gearbox you don't need 64 microsteps. Try 16, that should be in range.


On May 3, 2021 7:54:55 p.m. EDT, Kokoro San <alexchong79@...> wrote:

From my G8 single Axis,  if i put GR1 150 and GR2 180 the step calculation will over the limit of <= 61200  will it be fine?

 

 

    Stepper-Steps MICROSTEPS GR1 GR2 (Final stage)
AXIS1_STEPS_PER_DEGREE 1920000.00000 400 64 150 180 RA

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.


Dave Schwartz
 

Actually, even 16 might still be way too high. Many people drive these mounts with a 400 step motor with no gearbox directly coupled.


On May 3, 2021 8:03:23 p.m. EDT, Dave Schwartz <Dave.Schwartz@...> wrote:
It probably will not work. That is beyond the range OnStep can support properly. It is telling you that with the very high ratio in that gearbox you don't need 64 microsteps. Try 16, that should be in range.

On May 3, 2021 7:54:55 p.m. EDT, Kokoro San <alexchong79@...> wrote:

From my G8 single Axis,  if i put GR1 150 and GR2 180 the step calculation will over the limit of <= 61200  will it be fine?

 

 

    Stepper-Steps MICROSTEPS GR1 GR2 (Final stage)
AXIS1_STEPS_PER_DEGREE 1920000.00000 400 64 150 180 RA

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.


Drew 🔭📷🚴‍♂️
 

I don't see any gear reduction in your photos, they look direct coupled without gear reduction boxes. Are you sure those are not 150 step/rev motors?


 

I show two mount ~ one is  G11 with 2 axis both 360 teeth , another one is G8 with 180 teeth + gear reduction 150:1 


 

Thx Dave...Yes… even use 200 step also out of range....
Direct drive is the only choice… 


Khalid Baheyeldin
 

On Tue, May 4, 2021 at 07:20 AM, Kokoro San wrote:
another one is G8 with 180 teeth + gear reduction 150:1
That is your problem: extremely high gear reduction.

I also have a mount with a 180 worm wheel (Vixen SXD), and use 200 step motors
with 18:1 gear reduction.

My spreadsheet is like this:

200 step, 1/32, 18:1, 180 = 57600 steps per degree.

This is close to the 61,200 recommended limit.

For you to get that, you need:

200 step, 1/4, 150:1, 180 = 60000 steps per degree.

If you use a TMC StepStick it will do interpolation of microsteps, and 1/4 may work.

So the TMC5160 should work, in theory.

But per the spreadsheet, at 3 deg/sec slewing, the motors are doing 13,500 RPM, and
would most likely stall at this speed. Reducing the slewing speed to 1 deg/sec makes
it 4,500 RPM. Maybe that would work.

But you are certainly better off with less reduction. Somewhere between 10:1 to 15:1.


George Cushing
 

Yes, 1/4 looks reasonable. But the Losmandy SAIA steppers are not 400 steps. I think they are 24 step, 15° angle and the gear head reduction is 120:1. They were made in India.

Then there's the power issue, 83 Ohms means what, 150mA? 

Direct drive with 400 0.9° step angle and 64 µsteps may get you 0.91 arc-seconds a second resolution. But the same motor with a 3:1 GR1 and 32 µstep is 0.39 arc-seconds a second resolution. I'd work on getting some belt and pulley set up figured out. 


"Guilherme Vênere
 

My G8 runs with direct drive steppers and since I bought my Onstep kit with the steppers and brackets ready to install on the G8 I never cared about trying a reduction before.

But as George said the resolution in this case is very close to be a bother especially for astrophotography. I had many issues with this mount before (not related to OnStep) so only now i'm starting to check how this low resolution could affect my images, but it does seem to have an effect.

If you're starting from scratch i'd recommend looking at using reduction as suggested. 

Btw my imaging setup is a 102 F7 scope with an ASI1600 which gives me close to 1.1" per pixel so the resolution above is very close to my limit.

Guilherme


On Tue, May 4, 2021 at 3:33 PM George Cushing <stm32bluepill@...> wrote:
Yes, 1/4 looks reasonable. But the Losmandy SAIA steppers are not 400 steps. I think they are 24 step, 15° angle and the gear head reduction is 120:1. They were made in India.

Then there's the power issue, 83 Ohms means what, 150mA? 

Direct drive with 400 0.9° step angle and 64 µsteps may get you 0.91 arc-seconds a second resolution. But the same motor with a 3:1 GR1 and 32 µstep is 0.39 arc-seconds a second resolution. I'd work on getting some belt and pulley set up figured out. 


George Cushing
 

Yeah, but what are we going to do when those sub 2 micron pixels come along😨

I was refreshing my knowledge of the Motorola 68000 microcontroller and noted that it had 3.9 micron transistors in its memory. That's a moderate pixel size now.


 

On Wed, May 5, 2021 at 02:44 AM, Khalid Baheyeldin wrote:
you are certainly better off with less reduction. Somewhere between 10:1 to 15:1.
YES it was extremely high gear reduction. yet it was original come with the mount.
too bad the original control pane is damage.
 
Question:
1. If use direct drive stepper motor, what type of Torque kg.cm should be looking to buy?
2. Currently using Blue Pill board v1.8 + TMC5160 x2  RA & DEC / LV8729 x1 Focuser  / Firmware OnStep-release-3.16. (yet it will not run 4.24version)


 

 

i found 2 set or stepper motor 17GS4401S with 1.8 degree + 2 gear with teeth status 40 & 20 ( i think is 2:1 ratio ) from calculation 40/20=2

i think it will work with TMC5160 SPI micro step driver 
200 step, 128, 2:1, 180 = 25600 steps per degree.
STEPS_PER_WORMROT = 25600 
Question : 
1. more calculation steps per degree better or lest better or doesn't matter?
2. need set reverse drive in config setting for reveres motor installation?
 


andrea tasselli
 

1. A finer resolution is potentially better for imaging at high image scales. In your proposed configuration your predicted resolution is 0.88 micron per step which I believe is a bit too coarse for imaging at resolution less than 1"/pixel. It would be OK for visual observing though. You'll be better off using a higher GR1 and lower micro-stepping if you can afford it. I have similar configuration (180 teeth worm) and I have: 200 steps per revolution, 64 micro steps and GR1= 40/12.

2. Yes

On your previous question you can use 4.24 Master on a BluePill.


 

hello  andrea tasselli
 
i can use 400 steps with 0.9 degree stepper motor to reach higher steps at 51200 will that be enough?
--------------------------------------------------------------------------------------------------------------------------------------
    Stepper-Steps MICROSTEPS GR1 GR2
AXIS1_STEPS_PER_DEGREE     51200.00000 400 128 2 180
--------------------------------------------------------------------------------------------------------------------------------------


Dave Schwartz
 

Microsteps for the common step-stick drivers we use generally come in powers of 2 e.g. 2, 4, 8, 16, 32, 64, 128 and 256. I have seen external drivers that can have decimal rations e.g. 100 microsteps but these are not common - its all in the way the electronics are designed to slice up the waveform, generally using a microcode lookup table that operates more easily in binary.

On 2021-05-05 8:23 p.m., Kokoro San wrote:
hello  andrea tasselli
i can use *400* steps with *0.9* degree stepper motor to reach higher steps at *51200* .

or i can increases  microsteps to *153* x *4000* step to get *61200*? will /153/ step is allow?
--------------------------------------------------------------------------------------------------------------------------------------
Stepper-Steps MICROSTEPS GR1 GR2
AXIS1_STEPS_PER_DEGREE *  51200.00000* *400* *128* *2* *180*

*--------------------------------------------------------------------------------------------------------------------------------------*
Stepper-Steps MICROSTEPS GR1 GR2
AXIS1_STEPS_PER_DEGREE *  61200.00000* *400* *153* *2* *180*

--------------------------------------------------------------------------------------------------------------------------------------


 

On Wed, May 5, 2021 at 03:32 PM, andrea tasselli wrote:
On your previous question you can use 4.24 Master on a BluePill

 

i select PINMAP   STM32Blue  and i get compiling error :

In file included from C:\Users\alex_\Documents\Arduino\OnStep-release-4.24-G8\OnStep-release-4.24-G8.ino:68:0:

sketch\src/HAL/HAL.h:60:4: error: #error "For OnStep 4.x and later, Arduino_STM32 is deprecated in favour of STM32Duino board manager. See the Blue Pill Wiki for details"

   #error "For OnStep 4.x and later, Arduino_STM32 is deprecated in favour of STM32Duino board manager. See the Blue Pill Wiki for details"

    ^

Multiple libraries were found for "Wire.h"

 Used: C:\Program Files (x86)\Arduino\hardware\Arduino_STM32\STM32F1\libraries\Wire

 Not used: C:\Program Files (x86)\Arduino\hardware\Arduino_STM32\STM32F1\libraries\WireSlave

exit status 1

Error compiling for board Generic STM32F103C series.

 


Dave Schwartz
 

And don't get too hung up on getting as close as possible to that 61200 'limit'. Its very unlikely that your equipment or conditions will ever allow it to do you much good.

On 2021-05-05 8:36 p.m., Dave Schwartz wrote:
Microsteps for the common step-stick drivers we use generally come in powers of 2 e.g. 2, 4, 8, 16, 32, 64, 128 and 256. I have seen external drivers that can have decimal rations e.g. 100 microsteps but these are not common - its all in the way the electronics are designed to slice up the waveform, generally using a microcode lookup table that operates more easily in binary.

On 2021-05-05 8:23 p.m., Kokoro San wrote:
hello  andrea tasselli
i can use *400* steps with *0.9* degree stepper motor to reach higher steps at *51200* .

or i can increases  microsteps to *153* x *4000* step to get *61200*? will /153/ step is allow?
--------------------------------------------------------------------------------------------------------------------------------------

        Stepper-Steps     MICROSTEPS     GR1     GR2
AXIS1_STEPS_PER_DEGREE     *  51200.00000*     *400* *128*     *2*     *180*

*--------------------------------------------------------------------------------------------------------------------------------------*
        Stepper-Steps     MICROSTEPS     GR1     GR2
AXIS1_STEPS_PER_DEGREE     *  61200.00000*     *400* *153*     *2*     *180*

--------------------------------------------------------------------------------------------------------------------------------------




Dave Schwartz
 

For 4.24 you should be using the STM32duino board manager in place of the original Roger Clark board manager. The STM32duino is much more modern and allows the extra features of 4.24 to still be compiled to fit the 128KB memory size. STM32duino is backward compatible with 3.16.

Also, use the version of STM32duino mentioned in the Blue Pill Wiki which will get you version 1.9.0. DO NOT follow the messages that the 1.9.0 board manager gives you about going to a different URL and upgrading to 2.0.0... that version is incompatible with OnStep for reasons we don't fully understand yet.

On 2021-05-05 8:38 p.m., Kokoro San wrote:
On Wed, May 5, 2021 at 03:32 PM, andrea tasselli wrote:

On your previous question you can use 4.24 Master on a BluePill

*i select PINMAP   STM32Blue  and i get compiling error :

*

In file included from C:\Users\alex_\Documents\Arduino\OnStep-release-4.24-G8\OnStep-release-4.24-G8.ino:68:0:

sketch\src/HAL/HAL.h:60:4: error: #error "For OnStep 4.x and later, Arduino_STM32 is deprecated in favour of STM32Duino board manager. See the Blue Pill Wiki for details"

   #error "For OnStep 4.x and later, Arduino_STM32 is deprecated in favour of STM32Duino board manager. See the Blue Pill Wiki for details"

    ^

Multiple libraries were found for "Wire.h"

 Used: C:\Program Files (x86)\Arduino\hardware\Arduino_STM32\STM32F1\libraries\Wire

 Not used: C:\Program Files (x86)\Arduino\hardware\Arduino_STM32\STM32F1\libraries\WireSlave

exit status 1

Error compiling for board Generic STM32F103C series.