Pier construction (Tordmorden)

[FrenchyArnaud]

3 hours ago, Peter Drew said:

As the originator of the "Todmorden" pier I'm always pleased to see another one take shape.  Also pleased to see the mount bolted or fixed through the top of the block rather than a rat's cage.       🙂     

Nice to meet you 😁

[FrenchyArnaud]

58 minutes ago, FrenchyArnaud said:

I just realized that my azimuth bolts are dead (inner threads of the "nuts" are pretty much smooth) which means I need to do heavy repairs if possible or the mount is dead 😞 A bit gutted but trying to stay positive

Ok so I took the whole thing down and had a proper study of what is happening here. Let it be a lesson for everyone! Explanation: 

The azimut bolts (M6) are obviously pushing on the azimuth pin as they are screwed in. So, when you screw in you push the mount AWAY from the pin. If you screw the left bolt in, it causes the mount to rotate counterclockwise. Seems obvious? It is important to keep it in mind.

When I drilled the azimut hole to put the pin in place, rather that taping the hole and screwing the pin, I drilled .5 mm larger and screwed the pin through the disc using the thin bolt originally present. I did not think much about it ; it was an easier way with no foreseable negative consequence. 
How wrong was I.

The azimuth bolts are very, very tired, threads smoothened on bolts and nuts and maybe not as straight as they used to be. Consequently, they have quite a lot of play when not under load. The pin without the thin support bolt is 3mm shorter on the brake disc than the original config. And when you screw the left az.bolt in, the mount rotates counter clock wise. Still with me? The brake disc has more friction than the original bed of the tripod or maybe I over-tightened a bit. In any case, screwing clock-wise which rotates counter-clockwise produces a torque, vertical, downward on the pin. But the pin cannot move down, so the tip of the bolt moved up (it could, because there is so much play) and because the pin is now 3mm shorter, the bold was able to wedge itself between the pin and the roof of the central bolt support. So obviously, the more I tried to screw it in, the more I was wedging it in and my polar alignement was not going smoothly, the azimuth jittering randomly depending on the tension... 

So here is the lesson: if it does not go as planned, if it does random things that makes no sense, DO.NOT.INSIST. Stop and think. I was just in too much of a hurry to try. I did not take the time to assess. 

The good news is, I can fix the mount: I will put the thin bolt back where it belongs, for starters. I will tap the M6's into M8's to restaure minimal jitter (plenty of meat around the hole to do that safely) and I will put a tad of vaseline where the mount rests on the disc to avoid unwanted metal friction (and tension)

The bad news is, I am a cretin. Not just because I did insist without thinking, but because I had a very similar incident with this same mount last year, and ended up taping the alt.up bolt with an M10, which very much improved the behaviour of the mount. Still did not cross my mind this time! 

[Peter Drew]

All's well that ends well.     🙂

[CraigT82]

14 hours ago, FrenchyArnaud said:

I will put a tad of vaseline where the mount rests on the disc to avoid unwanted metal friction (and tension)

On my old EQ6 I used sheet PTFE 1mm thick (Amazon, about £8 I think for a 200mm square sheet).  I cut a circle out of it and placed it between mount head and tripod top.  Made polar aligning much easier - mount head, scope and counterweights totaled about 70kg so a lot of friction was present!

[FrenchyArnaud]

2 minutes ago, CraigT82 said:

On my old EQ6 I used sheet PTFE 1mm thick (Amazon, about £8 I think for a 200mm square sheet).  I cut a circle out of it and placed it between mount head and tripod top.  Made polar aligning much easier - mount head, scope and counterweights totaled about 70kg so a lot of friction was present!

That  sounds like a great pointer, I will investigate that straight away 👍

[FrenchyArnaud]

Well, i's all done! Now waiting for the next acceptable evening to do the PA and the inaugural session

 

Following the azimuth bolts incident, I tapped the nuts from M6 to M8 fine pitch (that is, preserving the original 1mm pitch and not going to 1.25mm) because I thought that would help with the precision of PA.  So as it stands, all PA bolts have been upgraded , M6s became M8s and M8 became M10s. I need to use a tool to turn them but that's ok - I am no longer supposed to do it daily. I might still insert a PTFE sheet under the mount base later on; for now a good spray of lithium grease will have to do. 

I buried the cables and pulled the 12V to the pier, passed both USB and 12V through the kitchen wall, ripped the last slabs and put the last gravel on. This is the finished product; I may in the future clad the pier with wood. For now, protection is provided by a bike waterproof cover sheet thingy  - whatever the actual name is - and the definitive cover is on its way. 

 

The only actual upgrade I am already considering is a zwo EAF - then I could 100% play from inside with this new toy! The few tests I have made the past few days confirned everything is working as it should and that it is ridiculously easier and faster to have everything running: it now takes about 45 seconds "to be in business" instead of my normal 90mins. Once the PA will be properly done, and decent calibration achieved, even with the focus to do by hand with a bathinov it will be under 5mins.  So... yes, happy days! 

The final bill?

Well, the first Jewsons bill for blocks concrete etc : £70
masonery drill bit (24mm*450mm) : £10
The whole of the gravel : 20*£4 approx.
Bits and bolts (taps, fine pitch bolts etc) about £12
USB with repeater : £12
12V bits : £20
BBQ cover : £25

Total : about £230 but that included resurfacing this half of the garden, about £150 without the gravel which is, after all, not directly used by the telescope. 

 

[StevieDvd]

Is that you in the last image, or did you get a man in to do the job and uploaded the wrong image? 😀

But to be serious I'm happy to see the end result and can't wait to see your astro images in further posts.

Bravo Monsieur

 

[FrenchyArnaud]

20 minutes ago, StevieDvd said:

Is that you in the last image, or did you get a man in to do the job and uploaded the wrong image? 😀

But to be serious I'm happy to see the end result and can't wait to see your astro images in further posts.

Bravo Monsieur

 

Yeps that is my ugly mug right there! Ugly but visibly happy 😁 I was reassembling everything (cables essentially) and the GF snapped it on her phone. Because, even if she is a proper pita on a daily basis, she is sincerely happy for me. In fact, she insisted that I should do it rather than wasting my life and nights carrying the stuff around. She's a gem, I just need to make sure she does not know it 😁

 

[Graeme]

That turned out really well Arnaud. And for a good price too! I hope you get many years of use out of it.

I would say go for the EAF.

Regards

Graeme

[CraigT82]

Nice work 👍🏼Looking forward to the first images from the new pier. I’d also say go for the EAF or whatever motor focuser… you can the just automate it all, set an imaging run going and just go to bed! 

[FrenchyArnaud]

13 minutes ago, Graeme said:

That turned out really well Arnaud. And for a good price too! I hope you get many years of use out of it.

I would say go for the EAF.

Regards

Graeme

Thanks
The EAF will come for sure - or an equivallent anyway. It's just that right now my budget has taken a hit with the build. I am looking into cheaper options but apparently it's not that easy to find. It will come at some point anyway!

[FrenchyArnaud]

2 minutes ago, CraigT82 said:

Nice work 👍🏼Looking forward to the first images from the new pier. I’d also say go for the EAF or whatever motor focuser… you can the just automate it all, set an imaging run going and just go to bed! 

Thanks!
Yes, that's the plan. I am looking for alternatives to the zwo that are more affordable, not found anything yet though. But it will be totally automated at some point, that is for sure  

[FrenchyArnaud]

On 14/02/2023 at 18:37, FrenchyArnaud said:

I am looking for alternatives to the zwo that are more affordable, not found anything yet though. But it will be totally automated at some point, that is for sure  

Well, no points for guessing what's happening there. 

 

New thread coming up soon...

[M40]

That will be another interesting thread to follow 👌 have a good search through the diy astronomer posts and hopefully you will find all sorts of component info that may be useful. 

[FrenchyArnaud]

Ok, so this is my first half decent  night with  full on imaging attempt. And I have to say, it was all totally worth it. 

I struggled a bit with balance then with calibration and eventually realised I have a major dew pb that needs addressing, but as it stands, despite a very mediocre seeing and a dec backlash measured at 5000ms (which forced me to spoil the PA to 3" to be able to guide South only) I currently have the best guiding I ever achieved with this 20yo battered mount! On average 0.80 arcsec, with lows to 0.65arcsec and highs of 1.05arsec (for ref, my camera + OTA has 1.83arsec/px ) Critically, pretty much 100% of subs are perfect (except for satellites of course) and it took me seconds to be in business. Of course, I have spent a few night in between working on alignment and calib but it is clearly doing ok now. I will now be able to take advantage of even very short cloud clearings! 

So... Yeps, defo worth it, I should have done tht years ago.  I need to sort the dew issue and build my autofocuser and I will be all set for a little while! Unless of course, I decide to take the mount apart and try to service it... Which is not totally excluded 😁

[FrenchyArnaud]

The autofocuser is on its way! That will be a massive upgrade

 

 

 

[FrenchyArnaud]

To conclude this thread once and for all, allow me to share the first images taken from the pier, with the DIY autofocuser running and the L-pro actually installed on the comma corrector (don't ask) 
My processing skills have not caught up yet but the overall improvement in the subs is absolutely enormous, with 90%+ keepers compared to my usual 50% on a good day and my stars are both much rounder and much tighter. Overall, there is no question that it was all well worth it! 

 

[Swoop1]

Your images put my deep sky efforts to shame Frenchy- well done!

As you say, the results make the work of installing your pier worth it.

[Graeme]

Great to see the results of your hard work!

Your M101 is a wall hanger!

 

 

[powerlord]

On 16/02/2023 at 22:43, FrenchyArnaud said:

Well, no points for guessing what's happening there. 

 

New thread coming up soon...

i did the same with my first OTA  - skymax.

do be aware though that those wee 28bys do not have a whole lot of torque to them -i ended up putting a step up to drive mine at 9v (from a 3.7v lipo) to get it to work ok.

let me rake out thread:

ah here it is:

 

 

[FrenchyArnaud]

4 hours ago, powerlord said:

do be aware though that those wee 28bys do not have a whole lot of torque to them

Hey  Actually, the focuser has been built, installed and thoroughly tested - it works absolutely perfectly. The thread is here: 

I had some doubts with the torque as this is something that always comes back in these discussions. However, this is only true with direct assembly. In my case, I had installed a belt and pulley which gave 2.5:1 gear ratio but on tests this gave me a too short course - so I changed the pulley for a 36 teeth that has the same diameter than the 10:1 knob,  and in this config, the motor has no problem pushing/pulling the camera in any orientation, including with the cooling box installed (dslr+cooling box = 1180g) , including with the focuser straight down, the motor having to lift the full weight with no mechanical avantage. In fact, I tried to stop the motor with my fingers and yes, I can, but the force to apply is VASTLY superior to the force I ever need to apply to move the focuser. 

I imagine that if you have a massive camera at 1000g+ AND the focuser is a bit stiff/tight, the motor might jump steps. If that eventually happens I too will have to stepup but after about 20hours of sessions and about 50 AF cycles it gave zero signs of weakness. I am building a second one for my C8N that I am converting into photographic; the focuser is of very, very poor build compared to the 130PDS and the knobs, though much bigger and giving a 4.75:1 gear ratio, do not have the secondary 10:1 knob. So it is very possible that with the extra friction, and having 4.75:1 instead of 10:1, the motor will prove out of its league. Well, I will shove a nema17 on the thing if needed   Also, I will put a rotary encoder on the other knob to monitor in real time if there are any issues with rpm or skipped steps. 

 

Edited March 8, 2023 by FrenchyArnaud

[Bruce Leeroy]

Well done on making the Daily Mail 👍

[FrenchyArnaud]

12 minutes ago, Bruce Leeroy said:

Well done on making the Daily Mail 👍

And the Mirror 😁

[FrenchyArnaud]

52 minutes ago, Bruce Leeroy said:

Well done on making the Daily Mail 👍

You meant Daily Express didn't you? I don't think the Daily Mail published If thry did, I need to know 🤭

[Bruce Leeroy]

https://www.dailymail.co.uk/news/article-11842575/Star-gazers-DIY-telescope-snaps-photo-Milky-Way-rivalling-NASAs-16bn-Hubble-telescope.html