Vroobel

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.

😊 Thanks! I don't know what to say... Maybe, when finished, my mount may go on a date with your OTA? 😁 To be honest, I had not too many other real ideas how to build aluminium fork based on the flat harmonic gear. It must be strong and relatively easy to build at home.

Hi, After some attempts with the Arduino Mega 2560 and AstroEQ firmware I had to leave it. I asked its author for access to higher number of micro steps, but they didn't response. 32 micro steps mode gives me 2 arcsec accuracy in Ra axis and 2.5 in Dec one. It's not acceptable for me. I focused then on the OnStep @ MKS Gen-L v2.1. As I use Nema 23 stepper motors, I chose the Trinamic TMC5160 drivers, because they have external MOSFETs onboard and can give really high current with small amount of heat. As an author of the OnStep firmware warned, I had to cut a CLK pin. I am possibly a second person who had to solder it to GND (in GoTo slew randomly Ra or Dec didn't work, now is OK)... It doesn't work with the EQMOD, because it's compatible with Meade standard. Instead of that I used the APT app and of course the ASCOM Platform. I am amazed... 😳 It's so silent! I recorded a Sirius-Polaris-Sirius slew as sample, just to share it on the YouTube. You can hear the mouse click louder than the stepper motors. Special thanks for my friend Sebastian from our Polish astro forum. He shared his knowledge and experience with me and patiently answers all my questions.

Hi, I have to rest a bit from the manufacturing, so it's good time to think about hardware and software. In the beginning I had a plan to rebuild my own software written for my previous mount, motorised Dobsonian one. But my friend, another astronomer amateur and DIY enthusiast encouraged me to look at the AstroEQ or the OnStep software which together with the EQMOD or EKOS can work perfectly in my setup. Thus lest start with the Arduino Mega 2560 with the AstroEQ. I'll try to work on the EQMOD on Windows 7 laptop (I have spare one) - just to be familiar with that. I know that the Arduino Mega is the worst solution as it is not accurate, so I ordered the MKS Gen-L v2.1 which will work with the OnStep. It's the best mobo for the mount and works wireless. Finally I'm gonna install the Astroberry and EKOS on my Raspberry Pi 4 8GB.

It's very impressive! Today we have laptops, Raspberry PIs, Arduino, but I see you had to make your own controller. The construction must be very accurate. Are you still using it? Amazing job!

😁 As I wrote earlier, the jack is not my idea. If it can hold a weight of a half average car lifted, why not to use it for around 40kg load? The item in pics is a chamfer tool for any round rod, including threaded ones. I have made 48 x M6 rods that means 96 round edges to chamfer. This tool does it quickly and smoothly.

Thanks for that, I'll consider it when (if) my ones will do same. But it seems to be aimed in fixed position. Edit: I have got a clever advice from another ATM creator: two steel flat bars with long hole along, one end screwed at the bottom of the wedge, second end screwed in position given by the angle. That should fix the wedge in the position enough.

Another actively spent afternoon:

Hello again, I'd like to share with you what I already performed. First of all I have made a plywood model of a wedge to avoid expensive mistakes. As another ATM maker from Poland suggested, I used a car jack for its elevation. It's strong enough to hold a one ton load. I have bought thick aluminium C-profiles and performed proper hinges for the jack. Four other high quality hinges (keeping dimensions) placed on edge will provide stability, so the wedge will not be wobbly. During performing the wedge I figured out that it will be better to weld the harmonic drive wall downwards instead of upwards, so the eyepiece - if I wish to observe - will be around 300mm lower. That is a significant difference. When some aluminium parts arrived I began working on the fork and fixing of the OTA. Several points of the mount at the same time. An aluminium base plate, 600x300x12mm with a big central hole and 16 small ones around for the harmonic drive, two round 600x30mm pillars in the middle of each side of the fork, two "tables" holding axes fixings. And here I have to explain my idea. I'm gonna use two high quality worm gears dedicated for CNC as axes holders. One of them - ratio 80:1 - will be driven by a Nema 23 stepper motor. I will remove the worm from another one with a 25:1 ratio, which I already had, so it will work as the axis holder only. I have designed and performed a kind of saddles holding my 10" OTA, which is 17kg load, without accessories. They will allow you to easily seat the OTA on the fork. I wrote it down very briefly, but it took me several months to get it done, mainly because of the waiting for the material. The sellers on eBay are now scammers and swindlers who use COVID and delays to sell goods they don't have in stock. I waited over one month for aluminium square and rectangular profiles and finally eBay gave me a refund for them. Now I wait again for the same stuff, but not from an eBay seller. I hope it will arrive on Monday, 7th June. In the meantime I have made some steel elements of the wedge. Supported by my friend I decided to fix the harmonic drive and its stepper motor to the fork permanently. This is because the fork base must be screwed to the harmonic drive using 16 bolts. It would be simply annoying to screw and unscrew it every time when I want to use the mount and finally the threads would be damaged. So the harmonic drive is attached to a 400x200x8mm steel plate. This plate will be put on the wedge top plate and screwed using eight welded M8 bolts. I expect that the steel wedge with the car jack will be heavy enough even without the harmonic drive, so the drive can be a part of quite light aluminium fork. The wedge top plate has a 90mm hole in the middle to let the stepper motor attached to the fork and the harmonic drive pass through. Using a 500x200x6mm steel plate I have made supporting triangles which will be welded on both sides of the wedge. It sounds complicated, but believe me, it will be very easy to assemble. All mount will be assembled using three parts: an "A" shape steel base, the wedge and the fork. I have 4m of 50x50x5mm steel square profiles for the "A" shape base. But this is the future... Regarding the mentioned earlier other OTAs, I'm gonna use a kind of shelf on the 300x30x30 aluminium bars (parts of the saddles) and screw it to them using M8 bolts. My idea is to install a rail in one of the existing standards to the shelf to be able to attach any OTA smaller and lighter thern my 10" Newtonian one. Tomasz

Exactly. In the meantime I found another cheap one from China including a 2" M48 barrel, so I ordered it. It will take longer time to finish my ATM EQ fork mount, so I will check its quality and accuracy without the cc. Its price causes that I have to collect the money. 😒

I checked it right now. My T2-E-mount adapter attached to the camera gives exactly 55mm space, so I think it's made as a standard. Unfortunately it's T2 thread, not the M48. I found 3 small headless screws and detached a T2 ring expecting the M48 one inside, but there is nothing useful. It will be difficult to find proper threated ring for this exact adapter. I think I have a choice between looking for another M48-E-mount adapter 36.5mm long and another same aplanatic 4-lens cc with the T2 thread. As the mentioned earlier Sky-Watcher one has also the M48 thread I tried to find the M48-E-mount adapter and found this one: William Optics M48 Wide T Mount For Sony Nex E Series. https://www.rothervalleyoptics.co.uk/william-optics-m48-wide-t-mount-for-sony-nex-e-series.html There is no information about its height on this website nor others, so I guess the height must be a standard. Thank you again Jamgood Tomasz