FrenchyArnaud

I just confirmed that all slewing/tracking functions are working as planned and the whole gizmo is identified automatically through ascom. Progress 🙂 VID-20230329-WA0004.mp4

I can't exactly answer these questions until I have finished my tests and mechanical design. The total reduction will depend on the microstepping acceptable (probably 32) and the guiding resolution (both could be adjusted a posteriori by flashing a new firmware, aiming for <0.1") but it looks like it will be in the region of 625:1 total.

At 64usteps and 19V (old laptop charger) around 1500rpm (20rps+) But that is obviously the higher limit. They are rated for 3200rpm but the 8bit arduino mega is the weak link - it just can't process the pulses fast enough. To be fair even if i limit it drastically to avoid overheating the motors and the drivers, it does not really matter. Even if the slew takes 5 minutes, I will take precision over speed any time of the day. The mechanics are not designed yet (just general ideas) and even the electronics are still evolving. For instance I am considering ditching the mega2560+ramps1.4 for a MKS Gen-L v2.1 ; it's technically equivallent but the MKS has a much better onboard clock which would avoid fiddling with a separate rtc. My idea is to have a brake directly on each axis, like a massive bolt pushing a friction pad, because it is much easier to design / build than an actual clutch.

I clocked a lot of this but I am always grateful for people giving their real life feedback and experience A4988 are in my understanding the real reason why you experienced stalling issues and snail slew rates... The OnStep wiki mentions it specifically and it can even get worse if you use an 8bit controller like me (Arduino Mega2560) Yes, after looking in depth into it at the suggestion of @LuckieEddie I decided to take that route because, even though it's not the most user friendly project ever, it is very, very well documented and seems really well developped and mature. I see no point in reinventing a wheel others have spent years perfecting before me when I don't even really understand the science of circles and disks. It will be difficult enough without discarding solid bases that are handed to me! Anyways! There has been quite some progress in design since the original post! So, first, the electronic base : I went for Arduino Mega2560 as the main controller, with a Ramps1.4 to support the connexions with no soldering. On that Ramps1.4 I have elected for drivers TMC2209. (The very active support group online made it perfectly clear that there are only 3 valid choices, 2130, 5160 and 2209 ; I originally ordered a pair of 2130, which never arrived ; then discovered that the 2209 are in fact more capable) The motors are 2 Nema17 with a native 0.9deg per step (400 full steps) at 4.4Newtons. (To be exact they are : JK42HM48-1684-16A and supposedly the most capable ones) Then, the mechanics: The drive train as it stands now will be 100% belts ; I am designing a 316:1 to 1250:1 gearbox that will totally eliminate the need for a gearworm and give a theoretical resolution of 0.04" and the torque will into the 10s of N. I spare you the maths 🤪 but on paper it is better than an eq6 and could carry 50kg without breaking a sweat even with 15% unbalanced. Both main axis will be marginally overdimensionned (car wheel bearings) and the whole structure will be assembled through massive bolts and a welded structure of square tubes. Right now the electronic part is on the bench, fully functional; if I plug it to the computer, NINA, PHD2 etc all say as a happy choir "Oh! A telescope is connected!". I can slew, track and goto. Of course, I will not be able to check that the pulse guiding fully works before it is actually in service but I don't have much concerns there. I am waiting for the delivery of a whole lot of mechanical / car parts and my brand new welding station because guess what, I never touched one of those in my life so I will need to learn this dark art before attempting to build the chassis. The bill for now is about £75 for the whole of the electronics and about £100 for the mechanical bits. My guess is that I will end up well within my £500 estimated budget and if it works as it looks like it should, it will be one hell of a piece of kit! Nope, say nothing, let me indulge in my dreams - I KNOW there will be major and unforeseen difficulties

Mmm... yes it is 🤭 You know what they say: it's not stupid if it works! I got the idea - and the disc! from here as a matter of fact 🤭

@FLO About that, HONESTLY! I really tried to place FLO even though there obviously was nothing in it for me, because I really appreciate the guys who went above an beyond to let me have a guide camera at a price I could afford lately, and were never dismissive with advise while being aware I bought a part second hand on ebay. Unfortunately it turned out you can't even mention a brand! When I tried to mention the scope as a SW130PDS, I was gently pushed to re-word as "a small 5" commercial telescope". So the camera was not a Cannon 450D but an old DSLR and the120mm was not a zwo but a guide camera. Etc. I can see the reasons why. But that felt a bit limiting

Honestly, it will be what it will be, I surely will not lose sleep over it. It's just a cool event in a bleak spring, I don't think my images are suddenly better because the media are interested

Of that I have no doubts! But to be fair, it's really only an ego booster, an opportunity to gain bragging rights with no real downside as I am painfully aware that pretty much everyone "who knows" will not be that impressed. It's just a funny thing to do and I am just vain and weak enough to enjoy the 15mins of attention.

I will tell everyone everywhere when it's due on, don't you worry 🤭 Even if you tried to miss it I won't let you, everyone needs to be told about my unfathomable genius 🤣🤣🤣

The reason seems to be the creativity and long term dedication - and of course the pictures themselves. It's for "The One Show", bbc1&2, 7:00pm daily. Prob a 3 to 4 minutes bit. I will know more soon.

EDIT -[ Airing tonight 23/05, BBC1 7pm, the One Show ] I cannot not share this with the community because you guys can appreciate... The BBC spent the whole day with me yesterday at home filming about my Pier of Doom. I REALLY tried to explain to them that most of you do much better pictures than me but somehow they did not buy it. Massive case of Imposter Syndrom here but that was pretty fun. That will be a short inconsequential segment of a few minutes but still pretty cool and a good ego boost. Date of broadcast still unknown 🙂

When I build my DIY EAF I came accross the same issue. The problem is that the metal core inside the plastic fine focus knob is dislodged and the plastic outer case of the knob just slides freely around the core. When you turn this knob, due to friction the plastic turns around the core without moving it, when you turn the coarse knob, core and casing both turn in sync because no force is applied between them. You need to pull the casing out cautiously, unscrew the tiny allen screw to free the core, then when you have both parts in your hand, a drop of superglue on inside the edge of the plastic then push the metal core back in (making SURE the screw thread and the opening in the knob casing are aligned!)

Another good pointer, thanks!

Thanls, a few interesting pointers there 👍

Hi guys, Starting yet a new thread for another diy build - but this time it could well be the diy project of a life time because, let's face it, I am too stupid and arrogant to know when I am out of my league. So, on the strength of "He did not know it was impossible so he did it", I am tackling the build from scratch of an equatorial mount with very serious ambitions, namely and in no particular order: - Must be able to take overkill loads without breaking a sweat, even if one day I can afford a quattro 12" or sthg like that. - Must have near perfect tracking speed - Must have negligeable backlash RA + Dec - Must be 100% ascom compatible so as to snuggle lovingly with NINA & PHD2, which also means - that it must be "pulse guiding capable" The things I DO NOT need, because it will be on the pier with illimited power supply: - A weight limit. Even if it ends up weighting 50kg: who cares. - Battery autonomy and reasonnable current use (it's on the mains) - Advanced Goto. I only need to be able to point roughly in the right direction, NINA will plate solve afterwards. With this in mind I have already determined quite a few things. Hardware: - Motors will be heavy duty steppers, NEMA17 or even 23. With low backlash gearboxes either 30:1 or 100:1 and the transmission will be 100% belts. First calculations tell me that can move up to 15kg of balance error which means it's effectively unlimited load. - The base will be a wedge, much easier to build rock solid than a GEM turret. - For now the plan is to have both axis free spining using car wheel bearings (there is pretty much zero play in these things and the load is obviously not a problem) - These axis will be hard mounted on a BIG steel barcket that will in effect act as the "chassis" of the mount. - It will embark its own RealTimeClock and Eprom so that it is effectively plug and play. Electronics: - prototyping and firmware/software dev is now on Arduino Nano and Uno but I will surely need a Mega plus a whole collection of rotary encoders, LCD, temp probes etc. For now I have just put 2 tiny steppers on a bread board to confirm that I can get it to be seen as a telescope by a basic ascom driver and get the motors to act as Ra+Dec. So yes, this tiny mess is, technically, a computerized telescope mount. First estimations tell that the build budget would be surprisingly low - in the order of £200 to £500 at the very, very max. In the other hand, the firmware and ascom driver could be really, really long to write. But hey, dream big. All ideas, inputs, remarks etc more than welcome.

Yeps and as a bonus you can export the image in full def, annotated, which is a very cool feature. I have found the functions to send directly the request for sthg on the picture to be ID'd and detailed via NED, which is also an amazing thing, basically "point and open the database on the relevant entry" - hours of fun right there for rain rainy days !

And the award for best advise of the year goes to @Paul M !!! This little plugin for ASTAP is just absolutely fabulous 🤪 And I cannot believe how fast it is; ASTAP was always really, really fast but Hyperleda is pretty much instantaneous. Never heard of it before; but I will never forget about it either! Ok, it's late March so it's about 1/4 of an award but still, spot on. Thanks Paul!

I might have mismatched my orientations... Looking into it, thanks for the pointer I have not... yet. I explored on stellarium and apparently the Markarian's Chain has quite a few really distant things with structure too... I might give both a go. Excellent point, I have it installed (it's my NINA plate solver) and I use it for stacking too, I never even thought of using it as a stand alone plate solver, trying tonight!👍

Hi guys, I was exploring the background of my recent images as it's a personal mania of mine to try and identify the furthest object I have pictured. (Currently, on this same image: NGC5422, 100 million LY) I found this smudge that is not even ID'd by telescopius - turns out it it is NGC 5471 - HII Ionized region. I scoured the internet and all databases I could find, no way to find the distance to that thing. Does anyone have the info? (and if so, I'd love to have access to the source of the info too!)

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

And the Mirror 😁

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.

Yes, exactly. From the arduino perspective, it's only turning leds on or off, totally oblivious to the relays themselves (these happen to be rated for 5V) This specific relay board has a native LOW logic though. Of course, there is always the possibility of connecting "normally on" rather than "normally off" but in some cases I might need to be able to turn the mount itself on without the laptop connected to it to command the relay HIGH (coil off, therefore circuit closed therefore mount powered) It follows that it is just simpler and safer to have the arduino ungrounded, to keep the total isolation and the LOW logic with Normally Off electric connexions. And I know what you think at that point: "lazy idiot, what prevents you from having some coils Normally On and others Normally Off?" Well, the answer is NOTHING 🤪 but I just did not see any downside to energising the coils separately and coding to initiate HIGH or LOW depending on the gear Besides, I know the risk of failure is low, especially with 12V 2A grounded in the relay while they are rated for 2500W, but it occured to me, should there be a failure, I prefer to increase the chances that the coils fail open rather than closed for obvious reasons. So... yes, that's why the jumper went off and the relay board is not grounded to the UNO. Also, remember - my first failure was due to too low current in the USB relay. I did the whole thing especially to be able to drive the coils on their own power, so psychologically, powering through the 5v pin was no satisfying. I might have over-engineered the thing a bit... But in that case I don't see a downside. 🤭

That's actually precisely the reason : if the GND of the relay board is connected to the arduino, you lose the benefit of the octo. It becomes conceivable that in case of catastrophic failure of a relay, this GND becomes live, fries the board and even the laptop on the other side (the relays are good for up to 10A) With the jumper removed , the coils are energized through a the VCC-JD and the arduino uses the IN pins to sink the current as grounds. Which is why the board is low-triggered (LOW pin means active coil here) and the only connexion between the arduino and the coils is the light of the LED in the octo - it becomes physically impossible for the current to leak anywhere. Connecting the GND arduino anywhere would defeat the purpose of octo isolation... Only the tiny 5v PSU grounds there. Even if it failed, there is no way it can damage anything - at worse, the UNO would fry but the gear on one side and the laptop on the other side are absolutely safe. EDIT - That's also the reason why the relays are interrupting the negative of the different elements : so that the relay board cannot, ever, become live, it's absolutely impossible.

A quick video of the actual box completed. The red wires are the 12V input that powers the coils via a tiny 12v>5V transformer, the arduino is powered by the USB and the two circuits are totally distinct with no possibility of electrical leak. The 4 cables are 4 junctions from the relays, meant to interrupt the ground of the gear, and of course the USB is supposed to be connected to the laptop via the hub on the pier. The box is 100% sealed with hot glue and I am confident it can take a storm without letting a drop of water in. WhatsApp Video 2023-03-07 at 21.22.43.mp4