Quote:
Originally Posted by Kal
Thanks Dennis, Mark & Jase for the supportive comments.
Trust me, I want to get it sorted!  I'm pretty sure it is not software related, PHD passes it's calibration and I see the guide star move in all 4 directions during the process. I tried .3x , .5x & 2x guide speeds on the Losmandy drive system, each with various backlash settings and various aggressive settings from 30% to 100% - forcing PHD to do a calibration each time, all to no avail. I always lose the guide star with it drifting East though, so the RA is pushing it too fast. I think it is a mount issue, I bought the mount earlier this year second hand and pulled it apart and regreased it (it's about 10 years old with the grease turning to slug problem common to older G11's) and I think the problem might lie with the RA worm gear not being flush to the RA gear from when I put it back together. I might offset my azimuth next time and drift the star through an image that I take with the DSLR to see what the RA gearing is doing exactly. Theres other people on the net reporting this so called "76 second error" which arises from the worm block not being flush, so it's the first thing I'll look at.
Once I get the problem sorted though I look forward to using this setup! Plenty of targets a non modded DSLR can hit before I will feel the need to move on  |
Hi Andrew I was reading this post. I have a second hand G11 as well and I use PHD guiding. I tried various guiding rates with 0.8x, 0.5x, 0.3x. That didn't really change anything in the guiding. What did make a huge difference though is balancing the mount and cleaning it. Try to swap the RA and DEC worm and keep the best for the RA. If you pulled everything apart, degrease it with some turp, let it dry then grease the bearings I used "Super Lube" Synthetic grease both in gel and spray. Use a minimal amount of grease so nothing drips on the clutches. The tricky part is to get the worm meshing right coz you need 4 hands and 20 fingers to do it.
Here's what I do. Unlock the two bolts that hold the end blocks. Push your index finger on the middle of the worm and push gently against the gear. With your thumb and major, squeeze the end blocks and slightly tighten the two screws (with your free hand
). Now the trick is to move your thumb and major slightly to the side that is away from the gear on the end blocks so they don't rotate when you tight them up. If you do this you'll hit the sweet spot with no backlash and the worm will turn by hand as free as it can be. The main problem with the worm not turning free is the end blocks/bearings being on an angle not the worm pressing too hard against the gear. Took me a while to figure that one out.
Hope this helps. Very cool picture btw.