Gina

I have an M8 threaded rod left over from my cannibalisation of the old Velleman kit 3D printer which I think may be suitable. It is stainless steel and I plan to use a SS nut in a 3D printed spur gear driven by a pinion on a little 28BYJ-48 geared stepper motor.

This leads me to think again about the method of remotely adjusting the elevation. I'm tending towards a threaded rod and tapped gear.

I've been looking at the elevation required for the mount at this latitude which is about 51°. Here is a diagram and series of photos as I adjusted the plates to give the right angle - it was higher than I thought

Pillow bearings mounted onto aluminium plate using M8 bolts, nuts and washers.

Printing finished. Two of the four spacers printed in PETG. They fit the mounting holes perfectly.

Spacers for pillow mount holes - oval holes 16mm x 20mm x 18mm deep with 8mm hole.

Interesting

The Titan extruders are probably the best things I've bought Well worth the money! As for filament I'm very impressed with rigid.ink - cost a bit more but what price good consistent printing!

What are the external dimensions of the D-Bot framework please Dave?

As you've seen, I'm getting considerable problems with my larger printer, particularly the Z drive system and trying to decide what to do about it. I think I shall need more V-grove extrusion and one option I'm considering is buying the ooznest D-Bot rail bundle. This is undoubtedly good value and could be cheaper than buying individual parts depending on how far I want to go.

I see that's the new smaller NEMA17 motor on your Titan Dave. Buying with a Titan extruder seems to be the only way of getting hold of them. Must be a lot lighter than the standard smallest NEMA17 as well as shorter

The Titan is a great extruder I'm pleased with both of mine. Take care with the front clear plastic cover though - it's not very strong. That's my only criticism. Making good progress Dave

Just realised - the casing belongs in the dome thread rather than the mount - DOH I'll continue there and keep this thread on topic Fork mount.

A bit further with the model just a pity I can't 3d print this in one go Or even two halves. That with the dome on the top would be aesthetically pleasing IMO All in matching green ABS.

Improved it a bit.

Managed to get "Follow Me" to work on the end. Not quite right and I'll have another go tomorrow.

Some more progress with the intersection. This shows the curved parts of the casing - the triangular sides are basically flat. There is end of the half cylinder to do yet though.

Here's the intersection. I think I need to increase the diameter of the half cylinder to match the dome support ring.

Concentrating on just the casing now. I'll intersect the semi-cylindrical part with the ring that takes the dome. I've included the top of the pillar mount for reference.

Thanks Julian No, I hadn't forgotten. I'm expecting to use two Pi3s.

The dome and some of the mount is no longer needed to model the casing.

Now modelling the casing - in stages. A mixture of 2D and 3D as I progress.

Thank you Here's another cross-section showing how I think it might continue from the bottom of the dome down to the wooden support framework (not shown). Below the dome and glued to it will be a circular ring with inside ledge resting on another circular ring which will be attached to the casing that reaches down to the support framework. I think the dome can be located by 3 or 4 small spur gears running on the inside of a circular ring gear on the dome. One of these would be driven by a stepper motor to rotate the dome.

It's a standard type of dome (though miniature) with a slot and shutter. See THIS THREAD

Fastest the 28BYJ-48 rotates is 10 rpm so if I used a 5:1 reduction on the belt drive it would take about 15s to move the rig 180° - that's fine. As for the resolution, half-stepping works out about 4076 steps/rev. which is 360/4076 = 0.0883°. With 5:1 further reduction angular resolution half-stepping = 360/(4076x5) = 0.0177 or about 18 pixels (0.001° per pixel with current lens and camera). Or with 16x micro-stepping = 18/8 or about 2 pixels. This is fine for the DEC axis. I think it might be reasonable to use the 28BYJ-48 stepper for RA as well but with a 10:1 belt drive ratio to give pixel resolution. 180° rotation would take 30 seconds - again adequate. This will simplify the construction.