Topics

New Onstep setup issues


ryol192718@...
 

Hi,
I'm hoping I can get some guidance on my setup. The problem I'm having is the GOTO is not getting anywhere near the object I'm going for. I'm starting out with the alignment settings and haven't tried going to a different object like the moon.  I'm sure it's the Config.h settings I have messed up. I'm new to stepper motors, gear ratios and astronomical tracking, so bear with me. I've replicated some of the setup from here since we have the same mount. https://www.cloudynights.com/topic/485116-diy-et-8-goto-mount/

here's my setup:
ET-8 equatorial mount
2x nema 17 200 step (1.8 degrees) motors
Arduino Mega2560, RAMPS 1.4, A4988 drivers
RA driven pulley: 60T
RA drive pulley: 15T
DEC driven pulley: 90T
DEC drive pulley: 15T

Based on my math for RA I should have a ratio of 4:1, DEC ratio of 6:1
Here's what I put in configuration calculator spreadsheet:
AXIS1     (Stepper-Steps)200     (Axis1 microsteps)16     (GR1)4     (GR2)1
AXIS2     (Stepper-Steps)200     (Axis2 microsteps)16     (GR1)6     (GR2)1

Slew Rate 2.00

After a ton of reading I'm still not sure what to put for the microsteps or the slew rate, so I picked values based on other's posts similar to my setup. 

My scenario: I polar align my mount. I go into the alignment settings on the OnStep app and select UMa-Dubhe, which should be RA 11h, 05m; DEC +61d 38'. The observed alignment is roughly RA 0.5h; DEC +70d. it doesn't run for very long.

I'm hoping someone can look it over and let me know where I went wrong. Thank you. 


philippe.larrieux@...
 

GR2 is invalid, it should be the number of teeth for each axis gear. From what I read for this mount, you should have:

 

For RA/Axis 1: 144

Dec/Axis2: 90

 

I don’t see your values in second email, but it should result to:

 

AXIS1_STEPS_PER_DEGREE

5120,00000

AXIS2_STEPS_PER_DEGREE

4800,00000

 

Ideally, you should check that the gears are effectively 144 and 90 teeth.

 

From: main@onstep.groups.io <main@onstep.groups.io> On Behalf Of ryol192718@...
Sent: lundi 29 mars 2021 05:01
To: main@onstep.groups.io
Subject: [onstep] New Onstep setup issues

 

Hi,
I'm hoping I can get some guidance on my setup. The problem I'm having is the GOTO is not getting anywhere near the object I'm going for. I'm starting out with the alignment settings and haven't tried going to a different object like the moon.  I'm sure it's the Config.h settings I have messed up. I'm new to stepper motors, gear ratios and astronomical tracking, so bear with me. I've replicated some of the setup from here since we have the same mount. https://www.cloudynights.com/topic/485116-diy-et-8-goto-mount/

here's my setup:
ET-8 equatorial mount
2x nema 17 200 step (1.8 degrees) motors
Arduino Mega2560, RAMPS 1.4, A4988 drivers
RA driven pulley: 60T
RA drive pulley: 15T
DEC driven pulley: 90T
DEC drive pulley: 15T

Based on my math for RA I should have a ratio of 4:1, DEC ratio of 6:1
Here's what I put in configuration calculator spreadsheet:
AXIS1     (Stepper-Steps)200     (Axis1 microsteps)16     (GR1)4     (GR2)1
AXIS2     (Stepper-Steps)200     (Axis2 microsteps)16     (GR1)6     (GR2)1

Slew Rate 2.00

After a ton of reading I'm still not sure what to put for the microsteps or the slew rate, so I picked values based on other's posts similar to my setup. 

My scenario: I polar align my mount. I go into the alignment settings on the OnStep app and select UMa-Dubhe, which should be RA 11h, 05m; DEC +61d 38'. The observed alignment is roughly RA 0.5h; DEC +70d. it doesn't run for very long.

I'm hoping someone can look it over and let me know where I went wrong. Thank you. 


ryol192718@...
 

I understand now, thank you! I will load the config.h file with those values and try it out. 

Here's another simple question, but I can't find the answer anywhere: for the RAMPS 1.4 setup, I have the drivers connected to the X and Y slots on the board, which one is RA and DEC? I'm guessing Axis 1 = RA which would be X making DEC Y? I've watched a few videos of RAMPS construction but no one has labels on the axis.


philippe.larrieux@...
 

Yes, that’s correct. You can see it in pinmap for ramps (Pins.Ramps14.h):

 

// Pins to Axis1 RA/Azm on RAMPS X

#define Axis1_EN             38     // Enable

….

// Axis2 Dec/Alt step/dir driver on RMAPS Y

#define Axis2_EN             56     // Enable (Pin A2)

….

// For rotator stepper driver on RAMPS Z

#define Axis3_EN             62     // Enable (Pin A8)

….

// For focuser1 stepper driver on RAMPS E0

#define Axis4_EN             24     // Enable

….

// For focuser2 stepper driver on RAMPS E1

#define Axis5_EN             30     // Enable

 

 

From: main@onstep.groups.io <main@onstep.groups.io> On Behalf Of ryol192718@...
Sent: mardi 30 mars 2021 15:46
To: main@onstep.groups.io
Subject: Re: [onstep] New Onstep setup issues

 

I understand now, thank you! I will load the config.h file with those values and try it out. 

Here's another simple question, but I can't find the answer anywhere: for the RAMPS 1.4 setup, I have the drivers connected to the X and Y slots on the board, which one is RA and DEC? I'm guessing Axis 1 = RA which would be X making DEC Y? I've watched a few videos of RAMPS construction but no one has labels on the axis.


ryol192718@...
 

I set Config.h to reflect 

AXIS1_STEPS_PER_DEGREE

5120,00000

AXIS2_STEPS_PER_DEGREE

4800,00000


When I try to do an alignment the motors wind up really fast and emit a high pitch whine. They don't spin at all. What should I look for and adjust next?


philippe.larrieux@...
 

I would guess improper vref. Did you adjust it properly ?

https://onstep.groups.io/g/main/wiki/3862


Howard Dutton
 

On Tue, Mar 30, 2021 at 08:53 PM, <ryol192718@...> wrote:
When I try to do an alignment the motors wind up really fast and emit a high pitch whine.
That's a motor stall.  So why are the motors spinning so fast...

Incorrect microstep mode set on the shunts under the drivers?


ryol192718@...
 

Sort of...I now realize I hadn't set the VREF again after I changed motors. I have set it correctly now. 


ryol192718@...
 

Thanks Mr. Dutton! I checked the board and the jumpers were set incorrectly. Everything moves and sounds good now. It needs some tweaking to get it fully dialed in but I think I have my major issues sorted out. 

Thanks again for both of your help!


ryol192718@...
 

I started trying to do 1, 2, 3 star alignments and noticed GOTO never reaches the right coordinates. Sometimes it's close and sometimes it's 10s of degrees off. 
I set to home and polar aligned. Then I did a manual GOTO for 3 hours 00 min; 90 degrees. It moved to 5 hours 20min. when returning to home it ends up at 1 hour 15 mins. I'm not sure what's going wrong now, please advise. 


Howard Dutton
 
Edited

Usually this is due to some wrong assumption or combination of wrong assumptions.

About the coordinates returned from OnStep and what they actually mean.
About steps per degree used for the axes.
About the micro-step mode the drivers are really in.
About gears not slipping.
About timing pulley tooth count.
About mount gear tooth count.

Usually if a motor stalls and looses steps during a slew the user immediately realizes something is wrong (due to the noise,) but that can do it too.


ryol192718@...
 

On Sun, Apr 4, 2021 at 07:34 AM, Howard Dutton wrote:
About the coordinates returned from OnStep and what they actually mean.
I was confused by that. When I enter coordinates 03hrs 00mins; +90deg 00' it returns 
RA = 12h 0.5m (03h 0.00m)
DEC = +89deg 52' (+90deg 0.00')

I'm not sure how it calculated 12h 0.5m.

About steps per degree used for the axes.
I have confirmed that my motors are 1.8 degrees per step (if I understand you correctly) If someone wants to verify themselves the number on the motor is 17HS4401. 

About the micro-step mode the drivers are really in.
Per RAMPS 1.4 documentation I have confirmed the drivers are in 1/16 micro-step mode. (3 jumpers installed under each driver)

About gears not slipping.
I have confirmed gears are not slipping using my phone's camera

About timing pulley tooth count.
timing pulley tooth count is 15T for both RA and DEC

About mount gear tooth count.
Mount gear is 60T for RA and 90T for DEC.


Howard Dutton
 
Edited

On Mon, Apr 5, 2021 at 04:44 PM, <ryol192718@...> wrote:
On Sun, Apr 4, 2021 at 07:34 AM, Howard Dutton wrote:
About the coordinates returned from OnStep and what they actually mean.
I was confused by that. When I enter coordinates 03hrs 00mins; +90deg 00' it returns 
No idea what "enter coordinates" means.  Not specific enough (but I'm guessing you entered the coordinates and did a goto to them in the Android App?)

RA = 12h 0.5m (03h 0.00m)
DEC = +89deg 52' (+90deg 0.00')

I'm not sure how it calculated 12h 0.5m.
Look at the Wiki FAQ #3 from the top.


Mike Ahner
 

On Tue, Apr 6, 2021 at 06:07 AM, Howard Dutton wrote:
Look at the Wiki FAQ #3 from the top.
ryol192718: Here is the link to the FAQ Howard refers to.
Wiki Frequently Asked Questions

The FAQ is not shown in the Wiki list on the right, you have to find it by using the Pages tab at the bottom. There are many addintional information pages available there as well.

-Mike


Dave Schwartz
 

???

Its never NOT been the first item in the 'Resources' section.

The only thing I have to use the 'Pages' dropdown to get to is the 'ConfigurationMaster' page which describes the Auxiliary Features.

On 2021-04-06 9:14 a.m., Mike Ahner wrote:

The FAQ is not shown in the Wiki list on the right, you have to find it by using the Pages tab at the bottom. There are many addintional information pages available there as well.