Gina

I was going to use NEMA17 motors for both axes but the ubiquitous 28BYJ-48 stepper motor with gearbox would be powerful enough I believe, particularly for the DEC drive. The smaller motor could be placed directly on the fork and save complications and weight. The gearbox has a ratio of 63.68395:1 which could be entered into the driver software/firmware just like the NEQ6 etc. had a peculiar gear ratio. With a gearbox in the motor casing a much lower ratio would be needed on the belt drive to the DEC axis on the fork.

Small change and drive pulleys added.

I've come back to this project having constructed a basic 3D printed dome and needing to see if this dome will work with the mount. The mount is probably over-engineered for what I'm proposing to put on it but as has been said - not such a bad thing. Means it's bigger than I would like but I already have all the main parts and most of the design so I don't want to start again. I think having put it to one side for a while and gained more experience and information it could be improved with a minor change in design. Here is a rough cross-section diagram of how it currently fits with the dome and a modified widefield imaging rig.

Beginning to take shape now

A4988 drivers use microstepping and never had any problem with them but I haven't tried PETG filament yet. I thought I might try as it doesn't give off nasty fumes but seems it would be easier to finish off my fume extraction systems.

Yes, that's my thinking too.

I shall be interested in how you get on with PETG filament. I've looked at it's properties, particularly compared with ABS which is my current favourite filament. The lack of fumes is certainly a plus point and means you don't need a fume enclosure. OTOH with the amount of filament I get through cost is a factor. Also, the ability to use acetone for solvent welding ABS is something I find very useful for making awkward or very large objects. I'm always on the lookout for different filaments though.

That's interesting Dave, I'm finding the same with Bowden feed and going back to a direct extruder on my Titan printer.

I can't offer any suggestions as to where to put it without knowing your house but as for appearance, you could make a nice wooden enclosure for it that looks like a cupboard or cabinet if you're any good at carpentry. Or buy something...

There are dozens of things you can make for the house with a 3D printer - I even have a pretty blue 3D printed toilet roll holder to match the bathroom colour scheme

Have you tried a System Restore back to when things were working? That has worked many times in the past for me but I haven't got Win 10 (except on a mini-PC box which I can't get to work and have put out of the way!).

Ooznest do seem to be a very good company - I've had very good service from them and their aluminium extrusion is a lot cheaper than other extrusion.

Handy to have it all cut to size and pre-tapped But how much extra did it cost you?

Here's a new model of the mount support parts. This is using the 300mm x 200mm aluminium plate I found this afternoon. This is actually bigger than the thicker base plate but that doesn't matter.

The hinges arrived in the post today plus some more aluminium channel and whilst clearing up this afternoon in my "Conquest of the Rats" project, came across some more pieces of aluminium. A sheet 300mm x 200mm x 3mm and two discs 7" diameter x 3mm and a few other bits that I don't think will help with this project.

The 500mm x 250mm x 10mm aluminium plate is quite a lot bigger than needed and causing problems with the roof box so I'll sort out something smaller. The 280mm x 170mm x 10mm to which I was going to attach the pillow block bearings, will be used as the base and the 300mm x 200mm x 4mm sheet will do for the bearings. To allow for PA adjustments a 200mm x 150mm x 4mm plate will be mounted on top of the base plate and attached to the bearing plate with hinges (as before, not shown here). A 200mm x 100mm x 4mm ali plate will provide an upright to support the top of the bearing plate. This can be attached to the moving plate with aluminium angle and to the bearing plate with bolts (not shown).

I have an acrylic disc about 6" diameter and 1" thick (I think) that I can turn on the lathe and use for both the connection of forks to aluminium tube and as the large pulley for the RA drive.

I was mistaken No aluminium discs - just the steel ones I'm using now. Been looking through my observatory build thread. I started with the 250mm diameter x 10mm thick steel discs and painted them white to match the NEQ6. A 200mm square x 5mm thick aluminium plate with the corners rounded off was used to make the ledge for the NEQ6, also painted white. When I got the EQ8 (in black) I repainted the steel discs black to match and didn't need the adapter plate. That should be around somewhere but probably not much good for the fork mount as the hole in the middle is too big. No wonder I can't find any aluminium discs!

I'm sure I should have two aluminium discs I got when I used the NEQ6 mount on my concrete pier and replaced with bigger and thicker steel plates when I upgraded to the EQ8. These plates should be around somewhere and I think would be suitable for mounting the forks onto the aluminium tube.

I'm still finding pieces of aluminium but no more of them useful for this project so far.

I've now ordered some aluminium channel for the fork - 1" x 1" x 1/16", which I intend to bolt together and to the 1" pipe. Hope this will be rigid enough.

I've ordered a pair of 3" stainless steel hinges. One small step...

This photo shows the idea for the Az adjustment. The smaller plate was one of the ones that carried the ST80 scopes on the 400mm triple rig and that was adjusted in the same two planes, with the Alt being with a screw up through the bottom of the big plate.

First 3D model. This shows the Alt adjustment. The orange part will be a 3D printed spur gear and will be matched with a smaller pinion on a stepper motor. The smaller horizontal plate will be lifted by the weight of the imaging rig by leverage with the pivot being at the left hand end of the plate. If it isn't lifted I can add a spring. The bolt that forms the Alt adjustment could be in a slot in the plate and then the plate can be turned in the horizontal plane, pivoting on the bolt on the left, providing the Az adjustment. The plate would be turned by an extension on the right with a nut on a threaded rod turned by gears and stepper motor. I used this method in the past for alignment on my 400mm triple imaging rig.

I think I have virtually sorted out the mounting and the PA adjustments. Here is a cross-section drawing and I'll draw and post some 3D versions shortly.