Hi all,
The first time I passed the 1000mm focal length and it failed. The avatar image shows how ring nebula look. The stars trailed, which i suspect is the rather large backlash in DEC. The auotguider can't take care of the large backlash. RA is perfect. I have found the set of screws on EQ-6 for the adjustment of the meshing of the worm.
Does anybody knows how to adjust the meshing of the spur gear and the motor gear?
At such a focal length, the mount plays the most crucial role.
Thanks.
Help! EQ-6, Atlas mount backlash adjustment
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kochu
- Posts: 817
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EQ-6 Backlash
Hi Meng Lee,
This may be of some help.
http://timsastroblog.blogspot.com/2007/ ... r-eq6.html
If Autaoguider does not catch up it can also be due to imbalance in the dec plane.
Kochu/27-9-07
This may be of some help.
http://timsastroblog.blogspot.com/2007/ ... r-eq6.html
If Autaoguider does not catch up it can also be due to imbalance in the dec plane.
Kochu/27-9-07
Last edited by kochu on Thu Sep 27, 2007 5:49 pm, edited 1 time in total.
Thanks Kochu. Hehe, his problem was even more serious.
Remus: Oops, I did not log the autoguider.
From what I see, when I press one DEC button, it moves smoothly. Then when I press the other DEC button, it jumps and then moves smoothly, every change in direction in DEC, it jumps. I did not set backlash compensations in the controller.
Let me see if I got change to log the autoguider.
Remus: Oops, I did not log the autoguider.
From what I see, when I press one DEC button, it moves smoothly. Then when I press the other DEC button, it jumps and then moves smoothly, every change in direction in DEC, it jumps. I did not set backlash compensations in the controller.
Let me see if I got change to log the autoguider.
Photo Album:
http://www.flickr.com/photos/14113965@N03/
http://www.flickr.com/photos/14113965@N03/
Hi Meng Lee,
Whether you set backlash compensation on the mount controller or CPU itself is dependent on what software you use for autoguiding. If there are means of software settings for backlash compensation on the program (like MaxIM DL, etc), then you do not have to set the backlash on the mount. The software will take care of it. But having the correct setting will take time to understand your mount character. It is good to spend a night or two 'learning' the guiding character of the mount. Try autoguiding at various declinations and 'investigate' each position approximately for at least 20 minutes. Let the mount 'settle down' per declination location and then see what are its error tendencies (X and Y -> RA and DEC or vice versa). If you say that the RA is tracking superbly, then concentrate on the DEC. You may notice that the balancing per declination will actually require subtle changes in the position level of the counterweight. It may not neccessary mean that when you balance for a given default position, it is fine for all other positions. This is so when you have offset equipment accessories like the protruding finderscope or the focuser (in the case of the newtonian). I have grown to get accustomed to balancing the system for every new object i am imaging per night. It changes slightly. It is always helpful to have a autoguiding log activated during the course of your exposures so that if anything happens, you can refer to the log for diagnostic issues.
On a separate issue, perhaps there might be additional stiction (slight) in your DEC gear. Stiction is the occurence between the teeth in the interacting gear system. This could be another reason based on the DEC gear system, because the RA gear system is constantly moving and may not happen. So when the DEC drive is stationary (no corrections done), the its gears are stuck together, not moving. When the worm do rotate due to corrective commands from the autoguiding software, it pulls on the teeth components of the DEC gear worm wheel. As such, this wheel can bend, or the mounting or bearings can flex, at right angles to the normal rotation. The resulting motion is usually backwards – you try to move the mount North, and it goes South! This only happens for a brief period of time after reversing directions; eventually the worm turns enough that the gear is forced to move in the correct direction. If you experience bad guiding in declination and cannot resolve it through adjusting the calibration process or changing the aggressiveness settings, you may have a stiction problem on the DEC. One way of solving this problem then, would be (and ironically) not have a perfect drift alignment. This will ensure that there will always be constant drift corrections in a consistent direction. However, you will need to avoid large drift alignment offsets enough to cause field rotation effects. Another way is to note the average drift amount in DEC and disable corrections that occur in that direction. The autoguider should only be able to push against the average drift, and not with it.
Whether you set backlash compensation on the mount controller or CPU itself is dependent on what software you use for autoguiding. If there are means of software settings for backlash compensation on the program (like MaxIM DL, etc), then you do not have to set the backlash on the mount. The software will take care of it. But having the correct setting will take time to understand your mount character. It is good to spend a night or two 'learning' the guiding character of the mount. Try autoguiding at various declinations and 'investigate' each position approximately for at least 20 minutes. Let the mount 'settle down' per declination location and then see what are its error tendencies (X and Y -> RA and DEC or vice versa). If you say that the RA is tracking superbly, then concentrate on the DEC. You may notice that the balancing per declination will actually require subtle changes in the position level of the counterweight. It may not neccessary mean that when you balance for a given default position, it is fine for all other positions. This is so when you have offset equipment accessories like the protruding finderscope or the focuser (in the case of the newtonian). I have grown to get accustomed to balancing the system for every new object i am imaging per night. It changes slightly. It is always helpful to have a autoguiding log activated during the course of your exposures so that if anything happens, you can refer to the log for diagnostic issues.
On a separate issue, perhaps there might be additional stiction (slight) in your DEC gear. Stiction is the occurence between the teeth in the interacting gear system. This could be another reason based on the DEC gear system, because the RA gear system is constantly moving and may not happen. So when the DEC drive is stationary (no corrections done), the its gears are stuck together, not moving. When the worm do rotate due to corrective commands from the autoguiding software, it pulls on the teeth components of the DEC gear worm wheel. As such, this wheel can bend, or the mounting or bearings can flex, at right angles to the normal rotation. The resulting motion is usually backwards – you try to move the mount North, and it goes South! This only happens for a brief period of time after reversing directions; eventually the worm turns enough that the gear is forced to move in the correct direction. If you experience bad guiding in declination and cannot resolve it through adjusting the calibration process or changing the aggressiveness settings, you may have a stiction problem on the DEC. One way of solving this problem then, would be (and ironically) not have a perfect drift alignment. This will ensure that there will always be constant drift corrections in a consistent direction. However, you will need to avoid large drift alignment offsets enough to cause field rotation effects. Another way is to note the average drift amount in DEC and disable corrections that occur in that direction. The autoguider should only be able to push against the average drift, and not with it.