The guiding has spat the dummy

[leon]

Hi Guys, it must be G11, "don't want to do what you ask time" :shrug:, any way tonight and the previous imaging run, my guiding has failed.

I use PHD and Orion Starshoot Auto Guider, and calibration is fine, and away it goes.

I have changed nothing on the mount and it has been setup like it is for the last 12 months and all has been well.

I suspect that it is the Mount, and I say this as since I have owned it from new it has not been serviced so to speak in regard to the bearings and gears.

Could it be that the lube has gone a bit off and is sticking, or can anyone shed any light on the subject.

Any suggestions would be muck appreciated.

Leon :thumbsup:

[Octane]

Leon,

Sorry to hear that! I take it you've given it a complete power cycle?

Is it a problem in RA or DEC?

I only just refitted a new gearbox to my declination axis tonight. I noted that the gear was rather stuck when it came out of the packaging. I had to apply quite a bit of force to get it to spin. Dad said it was probably just the grease that needed a bit of budging. Maybe I should have waited until after IISAC. I'd hate to go up there and find that I've got no guidance in declination! :)

Whatever it is, I hope you get it sorted. :(

Regards,
Humayun

[leon]

Humayun thanks for your response, the more i think about it the more i feel it is the lube, and it must stick every now and then, just enought time to throw the guiding out, and once that is out it stays out.

I'm sure i will get it sorted, it hasn't had a run for quite a while.

Leon

[Tandum]

Leon, If it has that white greese in the bearings, it is known to seperate over time into it's base ingredience. ie: oil and white stuff :) That said, I've read of a lot of losmandy problems being fixed with a factory reset and a setup from stratch.

[leon]

Thanks Robin, yea mate I think I best give it a good service this weekend, well what is left of it, probably tomorrow.
It is in an Observatory so it is well protected from the elements, but like everything needs some attention from time to time.

Leon

[avandonk]

Hi Leon try all the plugs and connections. Give them all a jiggle. If you lose electrical contact the guiding goes haywire.

After a long spell of cloud I always check that all the four directions actually work by clicking on the arrows on the guiding program.

Bert

[dugnsuz]

I sympathize leon!
My setup is doing almost the same thing - Uncanny!!!!
Doug
http://www.iceinspace.com.au/forum/showthread.php?p=505202#post505202

[multiweb]

Hi leon, if you haven't changed anything and it worked for months then yeah - definitely the lube. I got a bit of water in with the dew and moist weather this year and the grease in the radial bearings in DEC and RA was so thick it got really sticky at low temperatures and the mount wouldn't go anywhere, even with the clutches lose.

Pulled it apart, turped the whole lot and soaked it all in WD40 for half a day (bearings) then re-assembled. No problem then. I try to do this once a year in warm weather preferably, coz the meshing of the worms works best from warm to cold than the other way around in my experience.

EDIT: here's a tip for the worm meshing that works really well for me. Unbolt the whole DEC assembly from the RA. Leave both clutches in. Take both motors out, just leave the gearboxes with casing attached to base plate. Take traverse off DEC and unscrew both left and right DEC blocks. Unscrew the blocks to loosen them a bit. Now take the traverse and use it as a guide to align the left and right worm block by pushing the whole assemby against the gear so the worm meshes with the gear. While you're doing that push the right block against the worm as well. Tighten both blocks while pushing the traverse against the gear. That will stop the blocks from rotating and pinching the radial bearings on the worm (that's your 76s error there, twisted bearings popping up) when you tighten the hex screws on the back of the base plate. Now run your thumb or index on the Oldham coupler and everything should turn nicely. If it doesn't then shim the back of the right block and do the same again until everything turns nicely. If it does, do the whole 360 on the wheel. Note the "rough" points and shim/tighten again until you're happy with the whole 360. Do the same for the RA and you're good for another year until next November.

[leon]

Your all champions, many thanks for your responses.


Leon

[g__day]

So is it solved? When my guiding mis-behaves - I run the PHD guide checker in each direction to see all is okay. If you try to calibrate too close to the SCP and it fails - wierd things can happen.

[leon]

Matthew, no it is not solved as yet, to be honest i have not had a chance to get at it, have been very busy of late but i will certainly post my results when i get the chance.

Leon

[Bassnut]

Leon, can you describe the problem more accurately?. Does guide work, then suddenly the guide star jumps out of view, or what?. My experience with guiding on a G11, is it pays to analyse the problem before radical mechanical adjustments.

[mithrandir]

I find guiding close to the SCP much harder than the rest of the sky. Small errors in alignment make much bigger errors in tracking.

[leon]

Fred, Phd calibrates fine and away it goes, but then it decides to lose it's guide star, the guide star is reasonably bright, but not overly bright, lets say medium.

Then we get all these squiggly lines as you may have seen in the second post on this subject.

I intend to, when the weather clears, to do one image for a few minutes, without guiding, and see what results i get, obviously it wont be perfect tracking but it might led me in the right direction to what is the problem.

If i just get oblong stars, I will be happy and can say with some certainty that it is not the actually mount or it's working,

Then i will do the same run with PHD on and see what happens there, if i get the result as the image i displayed on the second post than it is definitly in the program.

We will see.

Andrew, yes mate i have experienced that as well and am quite aware of how difficult it can be to guide close to the pole.

Thank You for your response.

Leon

[multiweb]

Hi Leon, I still think you have bigger problems than PHD. Start by disabling the guide output in PHD and look at the graph. Your guide star will drift. Try to move the mount to polar align and balance it until you have an acceptable drift without guiding. Then kick in PHD so it sends guide commands and see what happens. I actually don't agree with the argument that it is harder to guide closer to the pole. I agree field rotation is more of an issue but in my experience guiding is way smoother and easier than closer to the equator.

[bmitchell82]

I have horrendus problems guiding anywhere near the SCP. once i get out away from it my guiding is perfect with very little movement (which can be seen by nice round stars). but phd struggles to calibrate even at something close to tuc

[Bassnut]

Yes, its MUCH easier at the pole, cant imagine where the idea its harder came from :shrug:

[bmitchell82]

well what am i doing wrong? phd just wont calibrate but will cal everywhere else.?

[multiweb]

You need to send much longer pulses to calibrate PHD around the pole so the star moves enough (in excess of 2s).

[Bassnut]

oops, sorry yes, as Marc says. I use a cal time of as much as 10 or 15 secs at the pole.

[leon]

Well many thaks guys your imput to this problem has been very helpful indeed, however time has caught up with me and i will have to do this fixing next week as i have to work for two days and then head off to Snake valley.

However rest assured, i will get to the bottom of this.

Leon

[MrB]

Sorry to go OT on you Leon, but I want to thank Marc and Fred for their tips re: SCP guiding.
These tips are gold for newbies like myself.
There really should be a 'Guiding for Dummies' thread somewhere with goldmine tips like these!
Thanks again guys! :thumbsup: