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DIY AstroEQ / Re: RA tracking speed
« on: September 20, 2018, 12:09:15 »
Just to update, I replaced the stepper drivers with new ones, actually used A4988s this time and all is good. Just had to set the RA and DEC directions to the opposite to the setting with the previous DRV8825 drivers. Accuracy and sidereal tracking much improved, able to slew to objects after three point alignment and they would be in the field of view, although I think the home position might be slightly off, I have read that the EQ5 setting circles can be a bit of a pain when trying to set this accurately.
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DIY AstroEQ / Re: RA tracking speed
« on: September 05, 2018, 07:52:15 »
Thank you for the info jslight. The calculations are useful information the fact that it appears to be a sensible factor out makes sense.
I did solder the jumpers.
I think it is my driver on the RA itself as when I swap them on the board the motor speeds also swap.
I'm using the latest firmware on Windows and the drivers are set correctly in config.
The steppers themselves are 0.8A rated with suggested voltage of 12V. I do find it difficult to set the current limit so the motors can turn with out getting too hot. 0.4V on the vref doesn't always seem to be able to turn it. I could get higher amp rated steppers.
I will update when I have tested with a new driver.
Thanks
I did solder the jumpers.
I think it is my driver on the RA itself as when I swap them on the board the motor speeds also swap.
I'm using the latest firmware on Windows and the drivers are set correctly in config.
The steppers themselves are 0.8A rated with suggested voltage of 12V. I do find it difficult to set the current limit so the motors can turn with out getting too hot. 0.4V on the vref doesn't always seem to be able to turn it. I could get higher amp rated steppers.
I will update when I have tested with a new driver.
Thanks
3
DIY AstroEQ / Re: RA tracking speed
« on: September 02, 2018, 12:54:22 »
Hi,
Something else to add on the problem, moving the mount in 800x sidereal speed for the RA seems to match the RA scale on my mount well. Slewing 1 hour in Eqmod moves the scale on the mount by one hour. Do it at slower speeds and it is way too fast. Not sure why the faster slew would be more accurate but might help with diagnosis of the problem.
Thanks again.
Dan
Something else to add on the problem, moving the mount in 800x sidereal speed for the RA seems to match the RA scale on my mount well. Slewing 1 hour in Eqmod moves the scale on the mount by one hour. Do it at slower speeds and it is way too fast. Not sure why the faster slew would be more accurate but might help with diagnosis of the problem.
Thanks again.
Dan
4
DIY AstroEQ / RA tracking speed
« on: September 02, 2018, 12:05:40 »
Hi,
Hopefully someone can help with this please. I'm having some accuracy issues with my DIY Astroeq which is set up on an SW EQ-5 mount with custom motors (NEMA14 1.8° step angle) and the pulleys as described on the FAQ section. The problem I seem to have is that the sidereal tracking doesn't seem to be correct. After three point alignment I seem to not be able to track reliably despite polar alignment, setting home position etc. The goto accuracy also then gets worse with time. I have tried switching motors and have also changed the microstepping value to try and help as it was a bit jumpy.
I think it may be moving too fast, it takes just under 14 seconds for the RA stepper to rotate once when at sidereal speed, is this correct please? When I slew with the DEC axis with the same rate the motor turns appears to be slower. I have used the custom mount settings in the config software so the settings should be okay.
Any help would be great.
Thanks in advance
Dan
Hopefully someone can help with this please. I'm having some accuracy issues with my DIY Astroeq which is set up on an SW EQ-5 mount with custom motors (NEMA14 1.8° step angle) and the pulleys as described on the FAQ section. The problem I seem to have is that the sidereal tracking doesn't seem to be correct. After three point alignment I seem to not be able to track reliably despite polar alignment, setting home position etc. The goto accuracy also then gets worse with time. I have tried switching motors and have also changed the microstepping value to try and help as it was a bit jumpy.
I think it may be moving too fast, it takes just under 14 seconds for the RA stepper to rotate once when at sidereal speed, is this correct please? When I slew with the DEC axis with the same rate the motor turns appears to be slower. I have used the custom mount settings in the config software so the settings should be okay.
Any help would be great.
Thanks in advance
Dan
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