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Sara you just keep setting the bar higher, that is an absolutely stunning image; I love the way the background stars shine through the dust and gas it gives a real sense of how tenuous these structures must be. The colour balance is perfect; what kind of dark magic do you wield Sara? Jim

This is an interesting thread. I've often wondered what are the perceived pros and con of the different type of focusers. Does anybody know? Jim

That's what I was thinking Gina, it's the lateral loads that I thought would be the problem in maintaining the precision in the location of the printer head - but he must have found a way to make it work to a satisfactory level at least. I wonder, could an oversized heated bed be more easily made from something akin to a large radiator? Easy enough to make a large surface area radiator, but maybe the temperature would not get high enough - just a thought. In any respect he has a fascinating design for sure. Jim

That is a fascinating design (hang printer), I'm surprised he is able to get rigidity in the system to keep precision in the printing. Jim

Up until their exit from service Nimrod navigators were still trained in the art of obtaining a navigational fix from a star shot. A little sextant type device was part of the equipment stored in the cabin just in case all else failed. Being based at Kinloss too would have been a delightful posting for any star gazer with the regular Northern light show during the winter months. Maybe the connection is indeed real. Jim

Cheers Alan. I did briefly consider sleeping in the car with it but my wife threatend to turn it into kindling if I did Jim

You made me laugh Mike. The first time I took the mirror into school was way back in February. Back then it was just the mirror box but I placed it in the car overnight. When I got to work and removed the lid the mirror was all frosted up, it took hours to clear! Jim

Thanks Mike, I hope it works well. I promised the pupils at school today to give them an early look at it even though it still needs finishing touches and a shake down. So it's packed up in the boot of the car, I feel like I should be putting a blanket around it Jim

Damian, niallk, thanks. In the short time I had to play with it on Sunday night I got the impression that there is a bit of a learning curve ahead of me on setting up and on using it effectively. Stand by for lots of questions and me looking for tips. I feel like I'm preparing for a Dob driving licence Jim

Thanks brantuk, it really has been an enjoyable project. Yes, I'm looking to stain it then put a clear satin varnish on it. I'm hesitating at the moment trying to find a decent wood stain/dye - I'm too indecisive. The ones I've found in the usual high street DIY chains all seem to be non alcohol based - the dye doesn't seem to penetrate the wood very well. The one I'm trying out at the moment is Coloron Wood Dye - a chestnut colour. I also need to flock the inside of the upper OTA and paint the inside of the mirror box black. I think the alt axis is fairly stable at the moment but it will need a proper shake down to expose any problems. I think you are right about a brace though between the two bearings. I think it would certainly do no harm but I'm worried it may detract from the clean lines of the circular box and bearings. I'll see how it performs once we start using it properly then make a decision, but I wouldn't be surprised if I end up adding a bracing bar or two. There may be a slight wobble between the two ground boards at lower elevations - I think it bounces a little when its moved in lower elevations. I think it can be solved with perhaps a few more contact points between the two circular boards - I've used teflon furniture gliders. Either that or a heavy mass sitting on the ground board but I'll try to avoid that. What I really need now is a good run of clear skys and decent weather to shake it down and find out how to use it. Jim

Yes the video camera of course, I was concentrating so much on getting the scope ready I forgot about that, thanks Andrew. While the kids will definitely want to get their eye to the eyepiece the video camera will be ideal for group sessions. To be honest the height of the scope just adds to the drama, it's going to look really impressive in the classroom. I took a fresh look at the VS focuser last night and it is a capable bit of kit but it is a bit heavy. I think I'm going to use it as a vertical stage for our DIY interferometer - it already has as good xy stage but lacks fine motion control in height adjustment (z axis). The VS will be more than up for the job. As for the effort - well what can I say, I spectacularly underestimated just how much time this would soak up. It has however been wholly enjoyable and very satisfying; you should have seen my face when I got the upper OTA secured on the truss tubes and had it fully assembled for the first time. I was skipping around the garden like a 12 year year old Photographs to follow of our first outing with it hopefully early December. Jim

Hurrah - it flys We had a clear night in Fife yesterday and I finally managed to set up a temporary jig so that I could measure and cut the truss tubes, wasn't easy but we got there. I took the scope out tonight and although the collimation is way out I was relieved that it could get the stars in focus. A couple of immediate observations: 1. Movement and balance - movement is nice and smooth, no jerking in either axis. Despite my concerns about the weight of the mirror box, the large moment arm means the scope is a little top heavy. It balanced perfectly with a 2lb lump hammer hanging from the box (hey it was easy to hand) so should be a relatively easy fix (i'll use something more refined than my lump hammer). 2. Moonlite connectors - performing really well although the tri point knobs for tightening the tubes in their sockets are not suitable for cold dark Scottish nights. They are too small, fiddly and the pointed ends really hurt against freezing cold fingers. I can see these being replaced with some round rubberised knobs. 3. It's big ! I need to rotate the upper tube so that the focuser is in a more convenient position for viewing (easy fix) . Notwithstanding that, the scope at F5, places the eyepiece well above eye-line of your average Scottish astronomer! Our diminutive height up here helps when running down haggis on the hills but not so good for tall telescopes Some form of suitable step will need to accompany the scope. 4. Setup - connecting the upper tube to the truss tubes and then to the lower assembly was a bit tricky - as one tube was located in a socket another would pop out. Maybe it was because it was the first time but it was a wee bit frustrating, there is probably a routine that works best so I'll figure it out. Strike down was really simple - took about 10 minutes to have it all packed away and back in the house. Ok so some fettling to do before I can take it into school. Apart from getting the scope stained and varnished, I need to sort out collimation and fashion some sort of shroud. December is looking good for our first star party, a nice Christmas treat. I'ts been hard work, about a year in total since picking the mirror up from Andrew, but it's a really great feeling getting to this stage, I'm quite excited about getting it into school its going to be a real talking point in class and it will certainly add something extra special to our courses. I'll be using the mirror on its own next week with the Higher Physics class as we look at refraction (Snell's law) - our trial at Schlieren photography (see earlier post) worked really well so I'm looking to incorporate it as an enhancement to our normal practical work. We are getting there Andrew, I now just need to work out how to mount that massive Van Slyke Inst focuser as well Jim

Cheers Damian, I'm really itching to get my eye to eyepiece on this. The weather really has been beyond frustrating but such is life I guess. Once I have the initial set up I'll be pestering you and the Dob Mob for some advice on fine tuning and operating tips Straightaway I can see that the size of the thing is going to present its own challenges. Jim

Had a good run at the build over the autumn break. Bearings and mirror box are all glued up now; really messy job but everything is nice and secure now, no more clamps Ground board is also complete and rather pleasingly the mirror box still moves smoothly in the alt bearings and rotates in dec without snagging. The truss tube are still waiting to be sized and fixed, I had hoped that would have been completed but the weather over the last two weeks has been dreadful with permanent cloud cover. So sizing and fixing the tubes will hopeful be done in the coming week. What remains then is the final strip down, sanding, staining and varnish, flocking the upper OTA. There is also some minor tweaking to be done - I'm guessing this is never really finished. The mirror cell has 3 upright posts that secure the mirror from sliding completely of the cell. To place the mirror in the cell when installed in the box one of the upright posts needs to be removed. Unfortunately, the screw securing the posts is not easily accessible when the cell is installed in the mirror box. I had though about drilling a hole through the mirror box to allow access to remove and secure the upright post but I think that would spoil the look of the box. I think what I'll do is removed one of the posts competently and install a modified "stop" fixed to the mirror box itself that can be removed from the top of the box. All of that probably doesn't make sense without a picture so I'll posts something later. Other than that, I think we are ready - so truss tubes fitted then a first light session hopefully early November with pupils at school with a visit to a dark sky site to follow Jim