PHD2 HEQ5 guide log

[teoria_del_big_bang]

The belt mod will do nothing for backlash in the worm. When I did the mod this is what took me the longest to get right. To get minimal backlash in the worm you have to tread very carefully when adjusting, too much clearance and there is too much backlash, too little and it binds and stalls the stepper. Also unless you are real lucky and have a real good set of well manufactured worm and mating gear you will not totally eliminate backlash at all I don't think. Certainly in mine there was quite a bit of cyclic error which meant once per rev of either the worm or the mating gear (can't remember now which it was) it binds more than when at 180 degrees different and so at this binding point you can remove backlash almost altogether but the as it revolves the backlash will increase as the clearance increases and you will probably see this cyclic error in the guide logs.

I do not know if FLO adjust the worm gears to get backlash as good as possible or not when they belt mod it or whether they assume it is already optimal.

Steve

Edited May 26, 2020 by teoria_del_big_bang

[Thalestris24]

1 hour ago, michael8554 said:

Hi Louise

I can see that the belt mod removes harmonics due to the spur gears, and runs quieter, but I don't understand how it can remove the fundamental, the worm and worm-gear backlash ?

Michael

Hi Michael

As others have said, any worm backlash is separate from the motors but I think it should be very small if adjusted correctly.

Louise

[Thalestris24]

1 hour ago, knobby said:

Agreed, it still has a worm drive so some backlash will still be there. Quite a lot by the looks of mine 🙂 

But seriously, I'm feeling seriously down about this, looks like another night of piddling around trying to get it to calibrate / guide.

Thanks all for your support.

That looks pretty awful, Knobby! Obviously you need to get calibration right in order for guiding to work properly. I assume you've input your scope focal length ok etc. And your PA is good (I always drift align using the PHD tool 🙂 ) Maybe have a word with FLO to check what they adjusted in respect of the belt mod and, what if any, testing they did.

Louise

[knobby]

4 hours ago, Thalestris24 said:

That looks pretty awful, Knobby! Obviously you need to get calibration right in order for guiding to work properly. I assume you've input your scope focal length ok etc. And your PA is good (I always drift align using the PHD tool 🙂 ) Maybe have a word with FLO to check what they adjusted in respect of the belt mod and, what if any, testing they did.

Louise

PA was excellent (according to Sharpcap) focal length in PHD2 was 1500mm (C8 / 0.7 reducer should be 1400mm in theory but images plate solve to 1500mm)

In defense of FLO I'm sure they would have to charge a lot more for Rowan fitting if they had to test the mount unless they had some kind of moving laser dot to test tracking ?

No testing tonight for me as cloudy.

[Thalestris24]

1 minute ago, knobby said:

PA was excellent (according to Sharpcap) focal length in PHD2 was 1500mm (C8 / 0.7 reducer should be 1400mm in theory but images plate solve to 1500mm)

In defense of FLO I'm sure they would have to charge a lot more for Rowan fitting if they had to test the mount unless they had some kind of moving laser dot to test tracking ?

No testing tonight for me as cloudy.

You could explain the situation to FLO and also ask them if it's ok to check the belt tensions without affecting the warranty. You could also try and see how it behaves with a lighter scope on the mount - eg your 72ed. Well, that's what I'd do, anyway.

Louise

[knobby]

15 minutes ago, Thalestris24 said:

You could explain the situation to FLO and also ask them if it's ok to check the belt tensions without affecting the warranty. You could also try and see how it behaves with a lighter scope on the mount - eg your 72ed. Well, that's what I'd do, anyway.

Louise

Thanks Louise, the 72 ed / finder guider is a good call, at least that will rule out the weight / focal length of the C8

[michael8554]

Cheer up knobby !

I would no longer worry about the poor Dec in Cal, as actual Dec performance is good because your PA is good.

But stop "Piddling About", follow the Guidelines, and in the right order, and you could get Dec Cal better.

Michael

[knobby]

Thanks all for your help , I decided to try the mount last night with the 72ed ( thinking if it can't guide that then what chance has the C8 got ) sure enough it calibrated fine with the default ( new profile wizard ) settings . Let it guide for a bit , looked good. Ran guide assistant and accepted suggestions. Still looking good (0.8 ish) but still having occasional veers up or down to 2 ish arc seconds .😟

Log attached - I think I'll be returning it as I've lost all confidence in it to be honest.

72ed/ reducer/ZWO efw/ovl oag/zwo1600

 

EDIT - its a real shame as poor @FLO now have to deal with what was probably caused in China trying to catch up with stock fulfilment due to Covid.

PHD2_GuideLog_2020-05-28_222123.txt

Edited May 29, 2020 by knobby
added info

[knobby]

Spoke to @FLO mount being collected on Monday, now have the weekend to decide between a replacement or go for a heavy ! EQ6R.

Cheers all, have a good weekend.

[wimvb]

12 hours ago, knobby said:

now have the weekend to decide between a replacement or go for a heavy ! EQ6R.

The eq6 will probably be more future proof. But it's also heavier, so better suited for a permanent setup.

[knobby]

I've seen good images taken with C8 / HEQ5 combos so will probably go for a replacement and hope it's a better one 🤞

Edited May 30, 2020 by knobby

[Thalestris24]

Just now, knobby said:

I've seen good images taken with C8 / HEQ5 combos so will probably go for a replacement and hope it's a better one 🤞

No reason why it shouldn't, Knobby! I fitted my own with a kit from Rowan. Over 5 years ago now. I remember I had to fiddle a bit to get the tension right and the scope balance right :-). I was grateful for the help I got on here:

Louise

[knobby]

Blimey, tale of horrors there 😟 glad you got it sorted though.

[Thalestris24]

6 minutes ago, knobby said:

Blimey, tale of horrors there 😟 glad you got it sorted though.

Not really - I was a beginner and doing things for the first time. It was a good learning experience. Once it was up and running I've never had to touch anything - it's been a great mod! 🙂 

Louise

[knobby]

Quick update, mounts gone back but out of stock for 15 days ... Sad face 😪 Almost went for a CEM40 but again, out of stock.

Looking forward to a good sample 🤞

Edited July 6, 2020 by knobby

[knobby]

Saga continues, since the replacement mount arrived had nothing but clouds! In desperation I set up last night but was pretty hazy and the gusts of wind got progressively worse all night. To compound the problems PHD2 chose my 1600mm instead of the 290mm to guide with ( not the mount or PHD2 fault but operator error) very frustrated.

Thinking of taking up cross stitching 😃

[newbie alert]

42 minutes ago, knobby said:

Saga continues, since the replacement mount arrived had nothing but clouds! In desperation I set up last night but was pretty hazy and the gusts of wind got progressively worse all night. To compound the problems PHD2 chose my 1600mm instead of the 290mm to guide with ( not the mount or PHD2 fault but operator error) very frustrated.

Thinking of taking up cross stitching 😃

No one that never made a mistake ever learned anything

[wimvb]

1 hour ago, knobby said:

Thinking of taking up cross stitching

You're not the first. 😉

 

[knobby]

Starting to feel pretty despondent 😞 tried again last night, got nowhere fast, PA spot on in 20 mins (Sharpcap) quick align, calibrated PHD2 (With correct cam) usual dec backlash messages ... ran guide assistant, accepted suggestions and guiding up and down + and minus 2 or 3 ... well balanced, no cables flapping. Guess I'm really asking too much of the mount although others do use the combo successfully. I'm starting to wonder if it's just my seeing is too poor here. Good news is that this mount is better / more consistent than the one it replaced 👍 

[Thalestris24]

5 minutes ago, knobby said:

Starting to feel pretty despondent 😞 tried again last night, got nowhere fast, PA spot on in 20 mins (Sharpcap) quick align, calibrated PHD2 (With correct cam) usual dec backlash messages ... ran guide assistant, accepted suggestions and guiding up and down + and minus 2 or 3 ... well balanced, no cables flapping. Guess I'm really asking too much of the mount although others do use the combo successfully. I'm starting to wonder if it's just my seeing is too poor here. Good news is that this mount is better / more consistent than the one it replaced 👍 

Hiya

It might just be the seeing - what was tracking like with the Guiding Assistant (i.e. guiding off)? You shouldn't really be getting any backlash with a belt mod (I've said before, I'm sure!).  Calibration should be very good lines. I still suspect you may not be perfectly balanced. When you run PHD2 for a while are the points on the target clustered around the centre (good!) or to one side (bad!)? If to one side that indicates imbalance. Another possibility is guide scope flex if guide errors are random. What was your star profile and snr like?

Louise

[knobby]

Thanks Louise, target points very random, using oag so guide star fairly iffy but was round and value in PhD was 5.8 (best I could get it). Mount is nice and free so I'm fairly sure balance was good.

Noticed another thread where @vlaiv suggests that a heavy scope needs the belt tighter than the 2mm flex with light finger pressure? I've emailed Rowan to see what they suggest. Really appreciate your time helping 😊

Edited July 7, 2020 by knobby

[Thalestris24]

1 minute ago, knobby said:

Thanks Louise, target points very random, using oag so guide star fairly iffy but was round and value in PhD was 5.8 (best I could get it). Mount is nice and free so I'm fairly sure balance was good.

Noticed another thread where @vlaiv suggests that a heavy scope needs the best tighter than the 2mm flex ? I've emailed Rowan to see what they suggest. Really appreciate your time helping 😊

Remember, it has to be balanced vertically as well as in RA and DEC 🙂 . Always make sure guide star is not saturated and has a good snr (or best you can get). Not sure what you mean by "the best tighter than the 2mm flex" ?? So with oag what fl are you using in PHD2? I've never used either a oag, or a SCT, or other long focal length scope, so I don't know how good the guiding would be expected to be. I'm sure someone else on here will have had the appropriate experience 🙂.

Louise

 

[knobby]

17 minutes ago, Thalestris24 said:

Remember, it has to be balanced vertically as well as in RA and DEC 🙂 . Always make sure guide star is not saturated and has a good snr (or best you can get). Not sure what you mean by "the best tighter than the 2mm flex" ?? So with oag what fl are you using in PHD2? I've never used either a oag, or a SCT, or other long focal length scope, so I don't know how good the guiding would be expected to be. I'm sure someone else on here will have had the appropriate experience 🙂.

Louise

 

Sorry, was multitasking 🙂 should have read 'belt' i'll edit post

[michael8554]

No point speculating, just post your Guidelog.

Michael

[knobby]

This ones from the 5th, bad night - windy etc, i'll dig out last nights when I finish work ... it was very short though as clouded over.

edit - added 6th

PHD2_GuideLog_2020-07-05_230017.txt

PHD2_GuideLog_2020-07-06_175601.txt

Edited July 7, 2020 by knobby