Vroobel

Hi, The night 7-8th September was great, I waited for so good weather! As you advised, I began the guide with a 2 sec exposure. The misalignment wasn't too big, only 1', but I wanted to check how it behaves with different misalignment. Next time I will try 5' and 10' to be able to choose the best setting. I found guiding settings giving me spread of +/- 1", which is almost perfect in comparison to the previous results. As the chart is not a goal itself, I can present two single pics of M13 and M57, 60s and ISO400, taken by my Sony Nex-6. I forgot to attach my IDAS LPS-D2 filter, so the black is light gray. Taking into account that my mount drives a 10" Newtonian telescope with 1270mm focal length and the guiding isn't yet set up perfectly, I must say that the stars are very point. Not everywhere in the field of course, I should buy a coma corrector in future. Apart from "improving" the misalignment next time I'll try to use a Barlow lens (2x 2" ED) and swap settings of the camera with 4:3 ratio. Let's see what the future holds. Thanks again for your support!

Thank you, guys. I will try it all as soon as possible. Thanks Michael for the PHD2 basics!

Thank you for your answer. Could you please explain what exactly should I calibrate? Thanks.

Good evening, I decided to create a separate thread from the one about my ATM fork mount. The mount is ready enough to begin astrophotography. I have taken an opportunity of several clear nights to set up my guiding, but after a failure every time I have no choice and have to ask for help. My guider is based on the SW 8(9)x50 180mm finderscope and the ASI120MM mini camera attached to the finderscope with an adapter designed and printed by me. It's OK. Recently I used a dew heater designed by me for the Baader Zoom 8-24 Mark III - it matches perfectly. I decided to go towards the Astroberry and Kstars/Ekos. I tried to use the built-in guiding software, but finally I chose the PHD2. Both with the built-in guiding software and the PHD2 I have never obtained satisfaction. Look please on the charts from last night (on the bottom). First of all I don't know whether the problem is caused by my lack of knowledge about the guiding or by the unknown fault of the OnStep @ MKS Gen-L v2.1 cooperating with the Astroberry. I have some bad experiences with the OnStep or the Ekos, but I hope that is another issue. Let's assume that everything is OK with the hardware/firmware. The Astroberry works on the Raspberry Pi 4 8GB RAM. A base of the mount is leveled properly. A wedge and fork are aimed excellently, originally using the SharpCap Pro, but recently using the modern Polar Alignment Tool from the Ekos. Both ways give an accuracy about several arc seconds in total. I know that people obtain arcminutes and the guiding can do its job. The wedge is stiff and the less than 20kg OTA with accesories are nothing for the mount as I hanged on it with my 70kg with no bigger stress, siriusly. I didn't weld the fork yet, it's aluminium, so I have to order the proper service. But the only bent I expect is towards its sides (left or right), which can be important, when the fork is rotated more than 60* left or right, never when the OTA is aimed near the Zenith. I found out that the OnStep may have problems driving the stepper motors when their wires are longer, so I changed the relevant parameter and compiled. Additionally I reduced the accuracy from 0.5 arcsec to 1 arcsec. I was advised to also consider a cone error, but still with no good result. As you can see in the pictures, the guider escapes towards North West (Is that because I live in Merseyside? 😁) In the second picture is an amazing concentration of the marks in the top left quarter of the Target chart. What did I try? - leveling with two different spirit levels, - changing algorithms, - changing an aggression around defaults, - binning 1 and 2 with relevant values of the MiMos (I understand that if MiMo=0.2 for binning 1 than it's 0.1 for binning 2, but maybe I'm wrong), - focusing the guider with the Bahtinov mask, - attaching the Baader UHC-S 1.25" filter on the camera for eliminating an IR; I have no 1.25" UV/IR cut filter, - Guiding Assistant and its suggestions, - Drift Polar Alignment (I damaged the excellent alignment this way, so I had to fix it in the classic way), - a Dec backlash analysis and attempts of use its results, - guiding with and without a calibration, - guiding using one and more stars, - manual and automatic choice of star(s), - and of course the exposure time between 0.5s and 6s. The guiding floats are usually in range (-2",+2"), but sometimes reach much more, like 8". I found out that the guider should be screwed using a more stable bracket with two rings, but it's not heavy, it's not 80mm APO. The recent nights have been windless and I am surrounded by fences, shed, house and trees, so no wind is in my garden. Because of unexpected backlash in the Dec axis the OTA is not balanced, so it's bottom goes down itselfs. As I understand, the only problem with the backlash can be visible during the GoTo, not during the tracking when the Dec stepper motor shouldn't work apart the guiding. Is it possible that the dev heater around the guider cell affects the air over the guider? I can try to guide without the heater tomorrow. I can also try to connect the OnStep controller to my laptop instead of the RPi. Maybe the 180mm focal length is wrong? I have a plan to make a kind of shelf which I will hang on the fork instead of the OTA. I will screw a spare finderscope shoe to use the guider as the only OTA on the fork. My idea is to check if the over 17kg load generates the problem somehow. BTW, I will use the shelf for another, smaller OTA or simply for my DSLR with a Sigma Zoom lens. Is there anyone who experienced a similar problem and sorted it?

Hi, Since my last post I made some additional amendments, everything for the ease of assembly and mobility. The electronics found a home in the fork frame, so it must be powered and the Ra stepper motor must be connected in easy and safe way. I like multi-pin sockets and plugs like the one used for connecting a microphone to CB or other radio station, so I use them everywhere it's reasonable. The stepper motors and the drivers are powered with 24V using a pulse inverter and it's good at home. But I have a plan to go somewhere under darker sky in future so I had to change the idea to be ready to power them from the car battery, which I have at home. Therefore I replaced the 24V pulse inverter with a 12V one supported by a 12V/24V 10A DC/DC inverter. It's placed in the fork frame as well, because some equipment (a dew heaters driver, an intervalometer, a dummy battery and a main mirror fan) requires the 12V power as well. BTW, the weather won't improve till September, so I can do much more peacefully...

Hi. Unexpectedly, yesterday my telescope got its first light on the new mount. I am delighted by the precision of a polar alignment given by both leveling and the mechanics of the wedge and also the home made guider (the SW finderscope and the ASI 120 MM mini camera) did the job excellently. I'm not so happy in relation to its tracking. I still have some error and I don't know yet what does bring it. After first several hours of use I have some vision about its modularity, cables and the assembling and disassembling ergonomics.

Hi. I still struggle with some parking issue: sometimes the mount stops much earlier than it suppose to do. But instead of wasting the time and looking for a solution, I improve the mount. I move step by step towards the maximal ease of assembly outside. Recently i worked on a way of arranging the electronic stuff and cables. Finally I figured out how to avoid tangling and hooking on obstacles like leveling knobs. The electronics found home inside one side of the road he fork. Its temporarily fastened on an MDF board, but I think that is a good place to it. I try to finish building this modular setup before clear nights begin.

Hi. Around one month ago I downloaded and installed the Astroberry on my new RPi4. I like the idea of everything in one place. But as my mount isn't entirely ready I decided to use temporarily the APT application, especially that more people use the Windows and ASCOM compatible software. I should take it into account when I need a support if any problem appears. And indeed, some problems appeared. Just for reminding, I use OnStep @ MKS Gen-L v2.1. One is about parking in wrong position. But at this stage it's acceptable. Second problem is more annoying, because every Park or Unpark command finishes with a crash of the Ekos-KStars. After several days of looking whether it's caused by the OnStep firmware or the MKS hardware I finally found a solution: the Ekos at 3.4.3 version had a conflict with the INDI driver for the OnStep. After updating and full-upgrading the Astroberry the problem of crashes disappeared at all. https://onstep.groups.io/g/main/topic/75830899?p=,,,20,0,0,0::,,,0,0,0,75830899

Hi, I have pleasure to present a first GoTo test: Polaris -> Deneb -> Polaris, performed at home because of rain. 😒 It's made with some stress included. I invested lot of money in fantastic high performance TMC5160 drivers, they are so nice, silent, but not working... After several seconds of work, in random moment they move into disabled mode, steppers stop while an application (the APT) still works. This is very confusing and generates big mess. I tried to find solution looking at forums, but people don't know why it happen, even if it's known problem. I still have some other drivers: A4988, DRV8825 and LV8729. The A4988 offers 16 micro steps while I need at least 64. It's current is not big enough as well. The DRV8825 offers 32 micro steps and also low current. There is big friction in the axes, the Ra needs 3A in GoTo mode, the Dec one needs around 2.5A. The LV8729 is quite good, it offers 128 micro steps, while the 2A of current cause that I can boil eggs... But it works fine for a while. And the poor TMC5160 ones... I told sorry to my DM556 industrial drivers which I bought several months ago. They offer 128 micro steps and 5.6A current! 😳. I set the LV8729 mode and connected everything with wires. It looks odd, I know, but it works perfectly. At home...

Yes, it is! 😁 This kind of harmonic drives work in a joint of industrial robot arms without a counterbalance. The arms are very heavy itself, while they are much more efficient than my mount. 😊 I see, that the fork is OK, when OTA is aimed somehow forwards or backwards, but I expect some bents, when the fork will rotate more left or right. That's why I have to consider welding, even if the profile and bolts are strong, they aren't strong enough to hold themselves and the fully equipped OTA. I'll check it as soon as the electronic stuff is ready and the weather allows.

Yes, that's strange. My one is simple. 😁

Hi, This is a fork mount based on a heavy 101:1 harmonic gear. It's designed for a 10" Bresser Messier Newtonian telescope, but will be able to drive any smaller OTA with standardised mounting. It's not in action yet, just finished enough to test it, but unfortunately there is cloudy sky, like usually when you want to test a new stuff... Here is link to a live story of my fork mount: I hope to show it in action very soon. 😊

Ok, so last several days I was very busy and productive. I designed and printed many knobs for different bolts and nuts and also adapter for 1.25" ASI 120MM mini camera which will work with SW 8x50 finderscope as cheap guider. I finished slides to be able to move the wedge in the Az axis with minimal friction, so the base is ready in general. Thanks to advice another friend from the Polish forum I also replaced most of M6 threaded rods with short stainless steel bolts, spring washers and nuts. The fork is much stronger now. And finally I finished all the mount enough to test it in action. Now all the setup is at home as I have to prepare some box for electronic stuff. There is still lot of work to do, but the most important work is done. I had a plan to build a mount able to hold 30+ kg equipment. Accidentally I made a 70+ kg one... 😳 I confirmed it hanging myself on the tops of the fork - the mount didn't move at all. I am very tired, but happy! 😁

Hi Craig, Thanks for your advice. I am ready to lock it in both Az and Alt axes. The Az is physically done while the Alt is partly performed. I'll finish the Alt one later or immediately if needed. I considered it rather against wobbling, but 4 hinges and the top plate supported on sides should make it solid. The car jack can lift and hold at least a half of the 1 ton car, so I think the 80kg shouldn't be a problem. I'll consider the Teflon instead of brass or bronze. As long as the weather is not good enough for test I have to focus on something else.

Nearly done. Three days of drilling, welding, grinding, I'm really tired. The 36.5kg of the wedge can be easily moved in the Az axis using one finger on the knob. But the wedge + harmonic drive and stepper motor + fork + OTA and its accessories will weigh around 80kg together, so I expect some slight resistance. I'll check it very soon.

😁 Thanks, it's nice, but I am only a DIY enthusiast who has a goal and simply has an idea how to reach it. 😊

Today I made two parts of the base responsible for an Az adjustment. Its precision is around 6.25' movement of the wedge in Az axis for every single revolution of the knob.

It's very close to finish. I mean the stage, when I can test it in action. There is still lot of work: grinding and painting. I have also to find a home for its electronic stuff.

Ah, OK. I had this as plan on the beginning, but my (to be honest - not my) solution is better. In Liverpool latitude is over 53*, so I have lot of space under the top surface of the wedge for its jack and stepper motor. In your solution I would have only 37 degrees. Moreover, in present position the heavy harmonic drive, motor, fork and finally the OTA push the wedge down, which is natural situation for the car jack. In opposite position the jack should be pulled up, while I'm not sure if it's OK for it. To prevent it the wedge should be very heavy, much more than the present 36kg.

Up side down? It will still be wedge, but not equatorial and without possibility to fasten to the base. Is it what you mean?

Hi. I changed mind: I made the longest elements of the base 90cm long, the narrow side of the trapeze is 35 while the widest one is 80cm. It's long enough. The wedge weights 36.1kg, the base - 18.6, that means nearly 55kg together. Now I have to ask professional for welding.

Hi. 3rd day in row: determining a centre of the mass. It's necessary for determining a size of the base platform. Finally I was able to hang my OTA without stress, but there was still needed some significant load to let it fall over. It should be really big guider with accessories. Now I know that I have to build a kind of trapeze-shape base platform around 80cm x 40cm, 110cm long.

I finally made the wedge. It's not finished yet, but it's enough to begin working on it's base. I have to calculate a size of the base. Unfortunately it became very heavy. I knew it, the wedge and the base must be heavy, but I didn't predict that it is difficult to lift it and move. I hope Its stability will be the best award for the effort.

Hi, This time something not so effective, but it took me two days to perform. The wedge, even if heavy (around 40kg), after aiming on a polar with side bolts (soon) may move with any touch. After my friend, who shared the idea of the wedge with me, I'm gonna use vertical bolts and nuts with knobs for a better stability. The front arched holes are for this purpose. 12 degrees of the adjustment range should be enough. As the wedge is made using 6mm steel plate, when I hang the harmonic gear on it, and then the fork, OTA and accessories (around 50kg!) they will try to lift a rear side of the wedge. So the rear arched holes are there for preventing of that. There is a 16mm hole between the rear arched holes - it is for an Az axis. The 16mm treaded rod supported with two bearings under and over the plate will be there for the polar aiming purpose, but it will also partly hold the wedge on a base.

Hi, Next step is done: a main construction of the equatorial wedge. It's heavy, while isn't finished yet. Its weight will be nearly 40kg when finished. Some additional steel part will be welded and some ideas towards higher stability will be deployed. Soon.