Tuned HEQ5 with Rowan Belt Guiding Problems?

[Sabalias]

Hi All,

A couple of months ago I replaced all the bearings in my HEQ5 and installed a belt mod. Maybe I was expecting too much but I'm getting a bit frustrated with the quality of guiding; it's better than before I stripped it down but not nearly as good as I was hoping for. Would some kind soul be able to take a look at the log below and let me know what might be wrong please? For reference this is what I have tried so far (using various sources including Astrobaby's):

• I've re-stripped the mount and checked everything is put together correctly. The axes both turn freely when not locked
• I've checked and re-checked the worm-gear meshing for backlash
• I've adjusted the worm-drive float (maybe it's wrongly adjusted?)
• I've tidied up (as much as possible) the cabling but I still have 4 power cables running to mains and one is very rigid)
• I regularly check the mount for cable drag etc but nothing obvious shows
• My kit weight is within tolerance
• The balance is as good as I can get it
• The mount is as level as I can get it

I have noticed that the belts on the drive slacken slightly when commanded to move in the opposite direction, which surprised me, and PHD2 tells me I have about 4000ms backlash. I have not yet got a dew heater on my guidescope (next purchase). Once I have figured out what's going on I'm planning on getting a power hub to reduce the dangling cables. Finally, there was no wind last night

Anyway, has anyone got any ideas? Is the mount operating as expected; in other words, am I expecting too much? Is it simply a duff mount (I found swarf in amongst the worm gears when I stripped it down to replace the bearings)?

Many thanks in advance,

Stu

PHD2_GuideLog_2023-02-07_182344.txt

[Sabalias]

Small update - I've had an email back from Rowan and I've made some adjustments to the belt tension and the 'slop' in the belt seems to have disappeared (I hope this will result in less backlash on PHD2). Is this all it could be?

Thanks,

Stu

[vlaiv]

I had issues with belt mod on my HEQ5 until I really tightened belts, then problems went away.

Quite possible that issue was due to belt tension.

[jfrijhoff]

Interested to hear the result, as I’m also in the market for such a modded HEQ5 Pro.

[Sabalias]

2 hours ago, vlaiv said:

I had issues with belt mod on my HEQ5 until I really tightened belts, then problems went away.

Quite possible that issue was due to belt tension.

Thanks Vlaiv, I was hoping you might be able to chime in 😉. The slack in the belts has all but disappeared but the flex seems to be a little less than the recommended 2mm; I could go a little tighter if necessary but I'll see how it goes on a trial run first..

Stu

[Sabalias]

1 hour ago, jfrijhoff said:

Interested to hear the result, as I’m also in the market for such a modded HEQ5 Pro.

I'll let you know how it goes. The tune and belt mod installation went pretty well by following various guides, so I recommend it if you are looking to enhance your mount (assuming my latest tweaking has worked and my mount is now performing well 😁).

Stu

[Sabalias]

Finally a clear night last night!  Attached is the latest guide log.

I'm a little surprised at the backlash remaining in the mount (clearly I have some more work to do on that) but I'm feeling better about the guiding (session 4). Having said that there were some drastic deviations in the first 15 mins of the main session; I guess these could have been shifting cables or slipping in the axes? Or could they have been caused by a passing vehicle (the third spike happened at the same time I went out to check on the mount so maybe there is a bit of vibration being detected)? Anyway, I might see if I can tighten the belts a tiny bit more and also revisit the worm meshing so make sure I have eliminated (as much as possible) the backlash.

Stu

PHD2_GuideLog_2023-02-13_184443.txt

[newbie alert]

Why are you calibrating on Dec 56.7?...

you could also tighten up your PA

A Error= 2.7 arc-min

What level of error are you looking to achieve as these are really budget mounts and always going to have machining inaccuracies

What does your calibration data look like, and have you a screenshot of your guiding?

[Sabalias]

1 hour ago, newbie alert said:

Why are you calibrating on Dec 56.7?...

you could also tighten up your PA

A Error= 2.7 arc-min

What level of error are you looking to achieve as these are really budget mounts and always going to have machining inaccuracies

What does your calibration data look like, and have you a screenshot of your guiding?

I’m not sure what you mean by calibrating on Dec 56.7. I’m just asking PHD2 to do it’s thing.  Edit - I see you are referring to the Dec angle at calibration; this is because I start guiding after slewing to the target. Presumably I need to get the calibration done before I start slewing?

For tightening up PA I probably need to start drift aligning or something because I think I’m as good as I can get using the polar scope. 

I’m happier with the guiding I got last night; previous attempts were really bad (hence the initial post). 

Stu

Edited February 14, 2023 by Sabalias

[malc-c]

Stu, PHD2 states that you should calibrate within 30 degrees of Dec 0. The ideal spot is the intersection of the meridian and the Celestial Equator, where you will have the most movement of a target star.

With regards to the belts.  Ideally you don't want any stretching or slack in the tension, otherwise you are not going to have any of the benefits a belt conversion offers over the geared system.   When I was developing a belt conversion 12 years ago (my doesn't time fly !)  I didn't use an idler wheel like the Rowan kit, but went direct between motor and worm pulleys, using the adjustment slots built into the mount for the motor fixings. You'll never get perfection as you'll still have backlash in the worm gear, which, given the pricing point of the mount is going to me manufactured to a certain level of tolerance.

[Sabalias]

4 minutes ago, malc-c said:

Stu, PHD2 states that you should calibrate within 30 degrees of Dec 0. The ideal spot is the intersection of the meridian and the Celestial Equator, where you will have the most movement of a target star.

With regards to the belts.  Ideally you don't want any stretching or slack in the tension, otherwise you are not going to have any of the benefits a belt conversion offers over the geared system.   When I was developing a belt conversion 12 years ago (my doesn't time fly !)  I didn't use an idler wheel like the Rowan kit, but went direct between motor and worm pulleys, using the adjustment slots built into the mount for the motor fixings. You'll never get perfection as you'll still have backlash in the worm gear, which, given the pricing point of the mount is going to me manufactured to a certain level of tolerance.

Thanks Malc,

So, to clear up my understanding, I would need to be calibrating with my scope pointing towards the south at a Dec angle of 0 degrees (+/- 30 degrees)? Shame my house is in the way 😂

Stu

[malc-c]

33 minutes ago, Sabalias said:

Thanks Malc,

So, to clear up my understanding, I would need to be calibrating with my scope pointing towards the south at a Dec angle of 0 degrees (+/- 30 degrees)? Shame my house is in the way 😂

Stu

That would be "ideal"....  not much you can do about the house.... unless you move 🤔

[newbie alert]

9 hours ago, Sabalias said:

I’m not sure what you mean by calibrating on Dec 56.7. I’m just asking PHD2 to do it’s thing.  Edit - I see you are referring to the Dec angle at calibration; this is because I start guiding after slewing to the target. Presumably I need to get the calibration done before I start slewing?

For tightening up PA I probably need to start drift aligning or something because I think I’m as good as I can get using the polar scope. 

I’m happier with the guiding I got last night; previous attempts were really bad (hence the initial post). 

Stu

Hi Stu, depends if you're pulse guiding or ST4, if ST4 you calibrate on every target and after the flip, if pulse guiding then you calibrate on the equator/ meridian

Polar scope pa is deemed a rough alignment

And to drift you need to point south, but as you say your house is there

Have you tried sharpcap?

[Sabalias]

12 hours ago, newbie alert said:

Hi Stu, depends if you're pulse guiding or ST4, if ST4 you calibrate on every target and after the flip, if pulse guiding then you calibrate on the equator/ meridian

Polar scope pa is deemed a rough alignment

And to drift you need to point south, but as you say your house is there

Have you tried sharpcap?

Thanks for the helpful info. I'm using pulse guiding through Astroberry so I will try the PA module in EKOS (as Sharpcap isn't available for my setup as far as I'm aware).

Stu

[newbie alert]

7 hours ago, Sabalias said:

Thanks for the helpful info. I'm using pulse guiding through Astroberry so I will try the PA module in EKOS (as Sharpcap isn't available for my setup as far as I'm aware).

Stu

I've heard thats quite accurate