EarthLife

Got magnets, other bits on way. 3D printed magnet holder/frame 150mm * 2mm laser off-cut steel disc for magnet backing (£2.80 each ebay) 15mm linear rail support (£5 AliEx) 15mm * 400mm hardened steel linear guide rod (£7 AliEx) 24 N52 neodymium magnets 20mm * 10mm * 4mm (£15 for 50 AliEx) 2 15mm I.D tapered roller bearings, will be preloaded (£6 each AliEx) - not yet shown Coils, stator and stator bearings - not yet shown Easy to scale up/down as required (bigger magnets for more torque etc). Can be reconfigured to position the magnets on the outer or inner side of a steel off-cut tube as the rotor. rather than using the disc configuration.

You can indeed, simple star tracking (with sub-pixel precision) is an easy first step to keeping it exactly on target (without a position feedback sensor). Friction drive is just another form of geared drive, just that it uses smooth surface contact rather than toothed gear contact.

Well the current 3D delta printer here can do up to around 200mm circular I think, so a 190mm diameter motor would be easy to do, which is actually quite big really. Have 50 neodymium rectangular bar magnets on the way for just £10 a pack, also about to order a pre-made steel 3D printer round bed plate for the magnet backing (helps a lot with the magnetic flux). Due to the huge uptake of 3D printer tech it's made available some very nice usable frame work items (solid bed plates, fine bearings, hardened chromium steel guide rods, etc etc etc) which helps a lot. Everything is going direct drive these days, even your home washing machine is now there, all the simple camera mounts on todays quad copters are very basic £2 direct drive motors (produces amazingly super smooth/stabilized video), yet the one application that has always screamed out for a cheap direct drive system is the amateur telescope, yet most are still using back-lashy gears and/or stretchy/bouncy belts and pully's. Their is no reason at all why a simple direct drive system has to cost the earth these days (apart from the obvious one of charging what they like - because they can). The electronics, firmware and software is the easiest part of it all so that's not a problem (control theory, PID's etc), high current full H-bridge drivers, MCU's etc have all come on leaps and bounds in the past 10 years. The home user can now get 10 decent sized multi-layer PCB's made for less than £20 now. Simple techniques for very fine position sensing has and is coming on too over the years, it is a challenge to get 0.1 arcsec feedback resolution without spending £100's, but there are ways and means. A good many people now have 3D printers at home (if not, then someone they know will have one), home CNC beds are also becoming more common. Time to make good use of them

Thank you for the replies, all very welcome ! Yes we making a direct drive mount, ie no gears, belts etc will ever be harmed in the making. Decided the position encoder is also going to be DIY using the capacitive vernier type method. That way we can get very high stepless precision very cheaply using simple PCB tracking,with it's own dedicated cortex M4 running the required position processing algorithms etc - The cheap digital vernier callipers you can buy these days use the same method of position sensing, although we will have somewhat higher resolution than a £3 digital calliper. The aim of the project is to create a cheap DIY'able direct drive + cheap high precision DIY'able position sensor mount. Looks like the motor itself is also going to be DIY, the magnets have been ordered, the copper wire for the windings is about to be (3D printer to be used for making the winding formers etc). The most expensive part we think is going to be the bearings and the steel/iron rings for the magnet mounting, the coils will be iron'less so that there won't be any cogging. The fun is in the experimentation, the learning and the DIY of it all.

Hello Has anyone out there tried using a couple of these for DIY direct drive at all ? .. https://www.aliexpress.com/item/32959689032.html It wouldn't be for a large telescope, just a smallish (6") SCT. The control board is easy enough to design (a decent cortex M4) and build so that's not a problem, plus a high resolution outer tape system for position fixing (as used on high precision printer/cnc positioning and cheaply available). Relative (as opposed to absolute) positioning is fine once the scope has locked onto a couple or so known stars/objects for calibration. Hi from the centre of England

Absolutely All that we see or seem is entirely based on human constructs, the way we experience life and all that there is, how we sense all that there is can only ever be based on view point as a being with limited senses and thought boundaries, a view point that can only ever really comprehend what it experiences using it's available senses. Try and describe what a colour looks like to someone that's never had eye sight, describe to them what an image is, or a picture, or video, or how we precisely see and know exactly what is happening at a distance purely by aiming our eyes towards it, describe what the experience of eye sight is really like to them. What senses are we missing (human race as a whole) that are required to move forward, to discover and comprehend all that we currently can't.

Whether we find it anywhere else other then here on Earth or not really makes no difference (apart from to ourselves), life is a totally natural part/evolutionary step of the universe as we know it, if it wasn't, then their would be no life.