What's Going On With My Mount?

[russellhq]

I'm trying to track down what's causing issues with my guiding and I think it might have something to do with my mount.

I've attached 2 SSs from PHDLab for one of my sessions from last night. As you can see there is a pretty regular hiccup in Declination in the first and a different but regular in the second. I'm not sure what's causing this or how to fix it??

[russellhq]

Bump

[themos]

Well, in the first one you have substantial polar alignment error. The declination hiccups might be reduced if you bias the balancing of the scope to be "East heavy".

[russellhq]

Thanks themos, though I'm pretty sure I never changed the alignment between graphs. What I may have changed is the dec setting in PHD from North (or South) in the first graph to Auto in the second.

I'll tighten up the PA and try again.

Also, looks like others have had similar problems:

http://stargazerslou...uiding +problem

I may need to strip down my mount after reading that

[mytola]

I'm no expert, but I think I've picked up that when balancing the counterweights, it's beneficial to make the balance slightly shifted so that the mount has to make effort to pull in the direction it's tracking instead of compensating backwards due to slight overbalancing. Might be that's what themos ment by east heavy. But please correct me if I'm wrong

[russellhq]

Thanks mytola, I should have said I had the mount slightly off balance so it kept the tension on the worm (I followed the astronomyshed video for balancing

)

[russellhq]

OK, so I had some clear skies and had another play with the mount. Here I picked a star near the meridian/equator and with guiding turned off (but recording tuned on), I got the following graph:

Now I can clearly see the PE of the mount in RA with guiding turned off. What's confused me is the DEC axis looks good for about 6/7 minutes but then starts to dive

[themos]

I would look to correct your polar alignment in the azimuth direction.

[russellhq]

I would look to correct your polar alignment in the azimuth direction.

Thanks themos. Do you know what could have caused the mount to appear to be aligned for the first 5 minutes but then took a tumble and started drifting?

[r3i]

Never seen the PHDLab software before - will have to try it out as it looks quite smart. Thanks for highlighting it.

[russellhq]

Never seen the PHDLab software before - will have to try it out as it looks quite smart. Thanks for highlighting it.

I found it a lot more copatible than the other software out there, the dev has made a good job of it! It has a "live" mode which moitors an active PHD session and gives you all sorts of numbers It also separates out the different calibration/guiding sessions so you can pick the one you want.

One thing I did find was that if you want to track a live session, you need to start with a fresh PHD log.

[themos]

Thanks themos. Do you know what could have caused the mount to appear to be aligned for the first 5 minutes but then took a tumble and started drifting?

Were you imaging directly south? I can't think of anything other than a shift in the mount supports, maybe a tripod leg sinking into the ground?

[russellhq]

I was about 20mins east of South. The tripod was stood on concrete and was pretty well set. I know that the Alt bolts are little bit suspect on the mount and have a bit of play in them. I'll be upgrading them (hopefully this weekend) to M10 or M12 toughened steel (12.9) and see what effect that has.

[russellhq]

So I've made a few adjustments to my mount and it's looking A LOT better!!

1st I replaced the bushes on the DEC worm with bearings as shown here by Serge:

http://www.iceinspac...282&postcount=2

2nd I replaced the bent Alt bolt (polar scope side) with an M10 bolt. This meant drilling out and tapping the hole. I changed the angle slightly so it hits the cam slightly higher up.

3rd I beefed up the cam with some steel as you can see in the picture below:

Doing all this helped me adjust the mount far easier in Alt than previously and also helped make things a bit more sturdy.

So I took another trace last night of a star with no guide pulses going to the mount and so went from this:

To this:

[reader34]

So I've made a few adjustments to my mount and it's looking A LOT better!!

1st I replaced the bushes on the DEC worm with bearings as shown here by Serge:

http://www.iceinspac...282&postcount=2

2nd I replaced the bent Alt bolt (polar scope side) with an M10 bolt. This meant drilling out and tapping the hole. I changed the angle slightly so it hits the cam slightly higher up.

3rd I beefed up the cam with some steel as you can see in the picture below:

Doing all this helped me adjust the mount far easier in Alt than previously and also helped make things a bit more sturdy.

So I took another trace last night of a star with no guide pulses going to the mount and so went from this:

To this:

Thats such a fantastic inprovement!

[Uhwaz]

i have EQ5 aswell mite look in those O rings i would suspect those doing the most