jif001

There are some photographs and diagrams on page 2 of this thread showing how JeromeW and I independently wired them up. They should help, but feel free to come back if not. You could start by simply replacing the existing motor (I’m pretty sure it’s just a NEMA 14) and checking that it works as it should, before going for the belt mod. if I remember correctly, the arrowed section on the attached diagram shows the original wiring to the RA motor (you may find your NEMA 14 comes with the colours shown in the top right-hand corner of the diagram, but not necessarily!)

I’m happy to send the STLs for the white ones if you’re still interested, but Jerome’s are good.

If you mean the yellow ones then those pics are not of my mount. @JeromeW is your man for those.

As far as I can tell (you may wish to confirm this) the EQ3Pro and the EQM35Pro are the same mount apart from the ability to convert the 35 into a simple RA tracker (i.e. the Dec motor and head are removable - M stands for ‘modular’). If that’s the case, you might find the attached link useful. See my message dated 11 May 2023.

It sounds like you are making some good refinements. Unfortunately I’m still out of commission due to the ongoing house remodelling and will be for a while, in addition to which there has only been one clear night here in months!

The planetary gearbox will have introduced some backlash - perhaps that’s the issue. Do you use PHD2? If so then you can use PHD2 Log Viewer (a separate downloadable application) to analyse the guiding performance and pinpoint issues - see the example plots on the first page of this thread.

It would work the other way. By using a 1.8° motor you would be doubling the overall speed, so you would need to halve it again through the transmission. That would mean using a 200:1 gearbox. Thanks for your input. You’ve moved the dec axis design on substantially from my original effort. I will eventually get a round to printing your designs, but right now we are in the middle of a house reconfiguration and my 3d printer is covered in dust 😬 I’ve recreated some of the components in Fusion 360 to make them editable and that’s kept me entertained for a while! I did wonder though - where does the nut barrel fit in?

I compared your transmission with mine and the original, see attached image, but can see nothing obviously wrong there. Our numbers match (360 motor turns equating to 1 turn of the axis) and differ from the original numbers (720:1) only because we are using 0.9° motors and different gearing (original Skywatcher is a 1.8° motor, resulting in a factor of 2 difference). The fact that you can’t turn the gearbox by hand doesn’t mean there is anything wrong with it - I can’t turn my focus motor by hand, but it’s fine. I’m just at the wrong end of the gear train to apply enough torque to it. What exactly happens? What’s the target if it’s falling 60° short, e.g. are you aiming for 90° and it stops at 30°?

Thanks for the files. The image looks good apart from the lack of calibration, which is easily corrected with darks and flats, and some aberration that indicates the camera is too close to the flattener/reducer. If you look closely, right in the corners, the stars look very slightly elongated in the direction of the image centre (see the image below, which exaggerates the effect). To fix it, you could 3d-print some thin spacers to put between the camera and the flattener/reducer.

Oh yes please!

Assuming your M42 image is not cropped, there is a small amount of aberration in the left-hand corners but it’s not bad at all and the field looks reasonably flat. The stars are a bit out of focus, which is affecting the image more. I don’t know what’s going on down the left edge - a light leak?

You may not need to go back to the drawing board - you may be able to just alter the wiring to the motor. See the extract below from this article. Also, see here (scroll way down the page) - nicely illustrated.

@JeromeW: I don’t want to divert this thread, but I have a quick question … what do you make of the Askar V? I’m considering buying one, but wondered in particular if it can achieve a flat field across all of its configurations. I know there is a flattener, but do the reducer and the extender flatten the field independently?

You seem to be doing with your EQ5 what I did with my EQM35. Have a look at this thread in the Mounts section - there may be some information you find useful.

Mark As you can see in the picture, I engineered some clearance so that the axis could turn fully without clashing, so maybe you need to make some small adjustments to avoid contact (or, as you say, modify the bracket). I used Fusion 360 for the design. There's a bit of a learning curve to it, but there are hundreds of tutorial videos on YouTube. Fusion 360 is very powerful and is used by professionals. For private use it is fully-functional (apart from some bits you will never need anyway), the only real restriction being that you can only have 10 editable projects at one time. I've never found that to be a problem - you can have as many projects as you want as long as only 10 (any 10) are in edit mode. I started out using Tinkercad (also free), which is easy to learn but creating complex designs is tricky. It might be a good place to start though. Jim