I finally reached the point where I was willing to try the dome shutter motor installation. I have questions about this that someone with a successful install can help answer. Note that I am not talking in any way about software or remote control. This is all about the mechanical aspects of the system. Some important starting conditions: the shutter moves by hand pretty well. I don't think perfection is possible but I'm happy enough with the motion. My system has the nylon shutter rails, circa mid-2020. I have posted elsewhere about this. I do still have a problem that the dome slit pinches down a bit near the zenith. If I lift this by hand in the middle, I can see the slit opening up. This comes into play later. Until now, I had installed a spreader bar that held the slit wider than it wanted to be. Without the spreader, the lower shutter would catch on the fixed part of the dome where the shutter moves. This interfered with the motor track installation and has now been removed. Now, on to the challenges. I hope some of you may have ideas or observations that will give me ideas that will help get this functional.
The first issue I want to ask about is the apparent interference between the motor rail (this is what has the embedded chain) and the nuts on the fasteners that hold the exterior nylon tracks in place. Look at the picture below. The arrow points to the bolt at the bottom of the track. Here I've had to take off the nut. There is no way for me to attached the motor rail and this nut without some sort of modification. I'm considering cutting out a pocket for the nut. I don't think it will compromise the motor rail but I clearly can't live with leaving that bolt out. My rail is 1" wide. The left shoulder is 0.325" and the right shoulder is 0.486". The bolt (sans nut) overlaps by 0.197". Do these measurements agree with an installed and working system? I'm a little suspicious that the chain is offset from the center here. In fact, were it to be mirrored left-right, there would be just enough room for the bolt. A thin nut would then fit without the need for any modifications.
This interference problem is more severe near the top of the dome. In the picture below, you see the originally intended nylon thread nut on the bolt. This interference creates a distortion to the track and where the gear can be and leads to other problems. You may note the wrinkle in the chain below the nut in the picture. I have a question about this later.
The picture below shows the top bolt on the right side. This bolt holds the dome segments together and is clearly not optional. However, there is an extreme amount of interference on this side from the back panel of the motor assembly. The offset of the track on the other side caused by the nut, causes the assembly to be shifted far enough that the side opposite of the motor is pushed hard against this side of the dome opening. The back plate runs into this with an overlap of about 3/4". I am considering lopping off that apparently extra material but this seems a bit extreme. However, note that I can eliminate the interference by lifting the dome on the inside to cause the slit width to increase. I don't think this is the answer, particularly since there's no way to introduce a structure to cause this spread. It is a concern, though. The interference on the other side is well less than 3/4" but it could be that I'm fighting both the pinching of the slit as well as the interference.
Now a question about the chain. In the picture below, I have taken the rail off and there is one link of the chain that is poking out. If you lay the rail out flat on the ground, the chain fits nicely in its groove. But, when you end the nylon rail to match the dome, the curvature makes the chain look too long. As the motor runs up and down the track, it pushes this chain "bubble" around and sometimes finds a way to jump over. My estimate is that the chain is about 3/4 of a link too long when installed. I don't know if this is a real problem or not. Perhaps it just works out but it sure looks strange.
The last item I want to show is the closed-dome sensor. The picture below shows the assembly in the lowest safe point it can reach before shutter and dome parts start jamming together just out of frame of this picture on the left. The gap between the sensor and the next closest bit of material on the fixed part of the dome is about 1". All of the descriptions I have found about placing the magnet do not match this view at all. There is nowhere to put the magnet that the system will be able to detect it. Note that you are only seeing one dimension here. The magnet is well past the edge of the dome and the sprocket track. That offset is also about an inch. To get the magnet in the right place would required building a bracket that mounts on the outside and reaches in and up to hold it in place. That would be very awkward and quite easy to snag an arm, sleeve, or coat on while peering out of the dome from the inside.
Ok, that's the brain dump for now. I think I have several partial solutions but nothing I've come up with so far is entirely satisfactory. On the good side, the motor mostly seems to do its job to move the shutter along the entire length of the track (with a lot of help right now). I'm interested in any information that indicates variations in dimensions and fit from what I have. I'm also interested in any tricks or even hacks you might have used to overcome even just part of what I'm seeing. Oh yes, one final bit of information about my rail. It's total length is 95.5" and the chain pins are 1 3/8" and 22" from their respective ends. I have three holes for mounting the rail to the dome. The rail itself is 0.5" thick.
Hmm, so many views, so few comments. BTW, I have also experienced the wind (~40 mph gust) pulling the shutter wheels out of the nylon track. I've had to completely abandon use of the dome and have removed my telescope and locked it down with external straps until I can find solutions to all these problems.