Peje

Good suggestion, done Have attached a screenshot of the output from guiding assistant, other than huge dec backlash I don't see anything interesting.

Thanks Carole, it is definitely a good suggestion but not quite the sort of thing I'm after. I totally accept this is a weird request for information, it's probably something I'll have to run down myself.

Hi All, Over the last while I've been considering a slight change in career direction. Currently I work for a global IP camera manufacturer, in the last decade I've gone from a Mechanical Engineering role, to Project Management and now I am an Engineering Manager & Engineering lead for all camera development. I really do enjoy the job I do & work with a great group of people. I have been very fortunate to have been given the opportunity to expand my role in new and interesting areas. I am passionate about my job and my desire for a change is not a reflection on the job I have today. What has really sparked this off is the realisation that if I can get so much enjoyment from a job that is loosely related to one of my hobbies (photography), how much more satisfaction could I get from something that is actually making a contribution to Astronomy, something that has fascinated me for many years. The Engineering side of astronomy is something I have no real information on. For example, is it driven by private companies who are contracted by larger Astronomy organisations or do either of these make contributions by themselves? My plan was that, rather than start talking to recruitment agencies who would inundate me with non-astro jobs and promises of large salaries, I would reach out directly to astronomy related companies who might be interested in someone with my skillset. The purpose of this topic was to see if anyone had any thoughts on the sort of companies / organisations that I should contact, or even just general feedback on my thought process. Thanks in advance, Pete

Updating PHD2 seems like a good idea, I hadn't noticed the flat portion of the line. I can grab the PHD2 debug logs are replot with some time after to see what it later does. It certainly could be a software glitch, the issue with that is it's unlikely I'll be able to fix it!

I will have to give that a try, one slight issue will be that this often happens when I'm not watching it so I only actually see it from time to time. Don't think it could be a loose cable, the comms are single Rx & Tx so a loose connection would knock out RA & Dec. This does seem reasonable, just need it to stop raining long enough to have a look It could potentially be explained by a slight slip in the dec but it's hard to explain why this would be happening as it doesn't happy when I extremely unbalance the OTA. I don't think this can be explained by a neutrally balanced OTA, it's too consistent. It drifts off then snaps back. As you say, it's not very high so I would expect this would happen more readily pointing towards zenith (which it didnt as that where my nights imaging began)

That's interesting, I have my cabling bundled in a loom with spiral wrap. The plus side is that I have RA and Dec as separate pieces so I can look specifically at one piece. Not totally convinced this is the issue but I don't have another ideas

As title, Most nights I get a spot of weird guiding error, normally I only notice it once but it may happen again when I'm in bed. Basically the Dec drifts off really far and then after maybe 5mins it seems to just snap back to what it should be. The attached image shows the event in PHD and the scope position. Looking at this position I doubt it is related to balance, which is set to be camera heavy. Anyone ever seen this before? My mount was stripped down during the summer, belt-modded and regreased; no problems with the worm were observed (I did ask the chap to check). This blip has been present for a couple of years so it isn't related to the rework. Keen to hear any thoughts. Pete

Looks like everything is fixed When I got home I refitted the scope and tested the dec to see if I could provoke the slip, even with the OTA being VERY unbalanced I couldn't make it slip. I loosened the belt tension a little and the strange sound went away also. Once that was complete I removed the dec motor, put thread-lock on the grub screws and refitted it. The borescope makes fitting the motor an absolute gift. The OTA is still on and I just need to re-attach the cabling over the weekend. which should only take a few mins because it's all tie wrapped together. Thanks for all the help in diagnosing folks

Hi All, Got the mount rebuilt this morning and backlash adjusted. Noticed when I run the dec at full speed I getting a periodic noise, it seems to coincide with the belt moving axially on the pulley (Video attached). It's not moving by very much so probably isn't a problem but I can't figure out what's causing it. I don't get the same movement or noise on the RA. Any thoughts? Going to test the slipping tonight and if all is well I'm going to pop the dec motor back out and thread-lock the grub screws. Potentially it could be this rubbing (and therefore vibration) that caused the screw to loosen. 190905_081817.mp4

Motor back in, less than 5 mins. I think I've found the solution to getting the belt on the motor... for me it was to remember I bought a cheap (maybe 6quid) usb bore-scope off Ebay a while ago. It took 3 or 4 mins to figure out the best angle for the camera and maybe 30secs to hook the belt over the motor!

It's not heavily unbalanced, even the weight of a dew shield was enough to knock it off. Strangely it worked before so I get the feeling something came loose or it is temperature related (cooler temp, tolerances increase)

This seems strange, I can't understand how adding belts at the drive end would eliminate backlash at the payload end; but that's a topic for another day If the mount was unbalanced slightly, what would you expect the behaviour to be? I presume it wouldn't be that the motor would turn but the OTA would not?

Slightly off topic but do I not need to have some imbalance to account for the backlash in the worm drive?

I'm not sure, if it's solid on the shaft I'm not sure what's to be gained from wrestling it out and refitting. Maybe I'm not seeing something, what would you expect to see when it's removed? This slipping only happened when the mount was under big load. It would work OK mostly but every few mins it would slip (motor sounded normal but no dec movement), it would also slip when I unbalanced the OTA to make it camera heavy. This is a good suggestion, similar to one tooth_dr said, with this cover off I can run the mount to see if the worm shaft is spinning when the dec fails to move. This will let me further refine the location of the problem. No nasty noise, this directed me towards the belt drive end of the system. Something that is earlier in the thread is an image showing one of the grub screws that attach the belt pulley to the dec motor completely loose.

Sorry, and another weird thing. For the shaft bearings, theres only a lock ring on one side. I found that when tapping I had pushed the pulley side bearing out a bit and the pulley fouled the casing. It wasnt difficult to fix though, I found it strange there wasnt a lock ring on both sides

That's a good idea though, I can remove a cap and see what the worm shaft is doing when the scope is doing the 'hopping' thing, this would give me a direction for the issue.

Didn't remove worm shaft as the pulley was really tight on it, I couldn't slide it off at all. I did a little tapping and got it to slide up a bit but it seemed like too much effort for no real gain and risk of breaking one of the bearings

Something I maybe didn't say previously, the motor pulley could slip easily when I loosened the second grub screw. For the worm shaft pulley, it was tight even after the grub screws were loosened. That said I couldn't get any real grip on the shaft to try and turn it

After looking at the guide, it looks like the clutch is just a grub screw and it's what connects the worm wheel to the saddle part. So if it's not after the worm (clutch) then it must be before the worm which leaves me with my 3 original options; Belt Tension, motor pulley or worm shaft pulley. Will rebuild it all and retest.

I was wondering this myself, not so much the clutch but something else in the axis like where the worm wheel engages with the main dec axis up towards the saddle. Typically I'm thinking about this after I've rebuilt that portion, at least that's easy to pull apart

Are we back to the motor pulley?

Stripped out the dec axis and no sign of the pullet being loose. It's so tight that I cant get it off. I've the dec refitted to the point where the idler goes in. Now I'm really stumped, where could the slip be coming from? The only bit I can see is the belt tension but it felt tight when I poked it with the back of a hacksaw blade. Any other thoughts? I cant see how the backlash adjustment could be to blame as that would likely be very noisy. Pete

The EQ8 is where I wanted to go next too, the main thing holding me back is the talk of backlash issues. To be fair though, I haven't really seen a better alternative option at the same price Pete

Me too. If nothing else it gives me a better feel for the design for any challenges that arise later in the season when the stakes are higher. I had to redo the worm mesh adjustment from scratch last month so I'm comfortable enough with that, just the motor fitting that I need to get to grips with. Had I been doing the belt mod myself I would have cut out slots in the casing for an endoscope, in theory I could still do this for the dec. Pete

Ah well, I partly figured I wasnt going to get off easy so earlier I removed the scope so removing the dec assembly wont be a huge pain. I dont fancy going through the pain of getting the motor back in, just to have to take it out again.