Telescope build 10" dob. Sort of finished (phase1) ..

[Joseki]

Well it definitely feels like this project will never be finished but having something I can now look through and see stuff seems like a good point to stop calling it a pile of parts and start calling it a telescope..

It started with a 10" f6.4 mirror from ebay.

The back story for my project is in some earlier posts:

First failed attempt, in which I made something unusable out of wood.

http://stargazerslou...1-hi-from-york/

After that I gave up a bit and decided to buy quality components. Also, I bought the shell of a skywatcher 250px flextube from Astroboot (which is also good quality). So not as impressive as something made from scratch but I don't claim to be great at DIY.

http://stargazerslou...tube-shell-mod/

Anyway, this is what it now looks like:

I've made the prototype mount (OSB board that I already had, primed and painted black gloss). Lazy susan bearing Az (I was going to add a friction screw but it seems okay without one). For the Altitude bearings, this photo shows more detail:

I'm quite please with how that turned out. I routed the altitude bearings from OSB board (new skill, new tool!). The bearings have a strip of aluminium bar mounted on - this was cheaper than importing ebony star, looks nice and may help the crumbly wood last a bit longer. On the mount I've put some 8mm thick teflon pads. The bearings are attached to the tube with a tube ring on the body and DJs "Rhino truss clamps" on the poles. There was quite a bit of lateral movement so I added two lengths of threaded brass bar connecting the two altitude bearings. This has improved it a lot. You can see this here:

Also, the big bodge of the mount is visible - the right side is too low! - so I raised the bearings with some scrap wood. Well it's only mk1 mount, though I want it to last a year or so.

What I'm most pleased about is the balance. With the tube ring at the top of the base tube, and the Rhino clamps extended as far as possible the telescope balances nicely on the bearings without any need for counterweights. The movement is pretty nice (at least it seems that way to me) and holds position well anywhere from horizontal to nearly vertical.

For the mirror cell and spider I got an optical supports cell from FLO whilst they were on offer (a fantastic item) and the spider is a destiny three vane curved spider.

I love the fact that these are really nice components. Drilling the tube went smoothly, though I had to take an angle grinder to the top tube ring to allow the destiny spider to fit at the same level as the original spider would have done.

A disappointment in the project was the focuser. Really I should have got the 2 speed skywatcher upgrade but instead got a 2nd hand JMI reverse crayford with motorized focuser (great fun actually). With the standard problem of skywatchers big focuser hole I decided to try a DIY solution. I made a mold, using the OTA as part of it and made a custom base plate using casting resin. This went quite well, though version two if I ever make one will involve me spending longer on producing a higher quality mold.

Well it looks like this:

Though I changed my mind and glossed over the glitter.

After all that and I'd mounted the focuser I was making some fine adjustments. It turned out that one of the bearings on the focuser was broken :mad: . I think I can replace it but I may need a new tool to cut off the old one (leaving the bearing pin intact) - hello Dr Dremel!. So off came the JMI and on went a 'vintage' all metal R&P focuser, which is actually very nice, no wobbles (a small amount of Lithium grease added for luck). 'Fix JMI' is a project for another day.

Waiting for a clear sky, I've made a start on flocking the tube interior (Wilkinson's material). The telescope desperately needs collimation but I've pretty much run out of hobby money. I did buy Sky at Night and the cling film will soon be disappearing from the kitchen as it has the right sized tube for their DIY combination tool. Actually I was looking around for some plastic tubing last week for this and for some strange reason all the tubing in Wicks, Wilkinson and BnQ that are labelled 32mm are actaully 35mm OD, whilst the 25mm tubing is 25mm OD - must be some sort of secret plumbers code. meh. (internal diameter is 29-30 mm).

However I set it up outside last week just to see whether I see anything at all. I can't really do it justice with a proper first light report as this is also my first telescope (turn left at Orion will be arriving for Christmas - thanks Mrs Wife!). The moon was pretty fantastic though even with the dodgy collimation. I also managed to point it at Jupiter which was even more fantastic - bands! moons! very exciting! Unfortunately I only have a 25mm EP at the moment and had been too time pressured to leave it out to cool down properly, so I'm expecting a big improvement in the future. After 30 minutes the secondary fogged up as expected (our garden is quite wet).

I got a plastic Seben 6x30 finderscope on ebay, though that's not been properly aligned yet. Okay for the money but horrible optics. It did answer the question on whether I need a right angled finderscope (I don't).

Anyway I'm pretty excited to have got this far. Perhaps someone with more experience of using telescopes would say it has issues with X,Y,Z but I'd rather not know just yet!

As I said at the start this is no-where near finished. First I need to sort out collimation, buy some more EPs and make a dewshield and shroud. I'm interested in the thermal management and I'll be experimenting with DIY dew heaters (I've now got four LED dimmer boxes and will be getting a Dremel versatip soldering iron for Christmas (old skill refreshed, new tool)). I've also bought two temperature probes and display combinations - I'd like a display showing mirror temperature and outside temperature. I've read Alan Adler's article and want to try a side fan as well as the back fan. With regards the back fan the optical supports cell has a lovely mounting point but directly mounting the fan is not recomended it seems when it's used during the observing session so that might have to go to waste.

I've been thinking about gemreds but the Astro-Fix appears to have been updated, may be good enough resolution, costs about the same as a pair of gemreds and would avoid problem of whether my DIY skills are up to mounting it properly.

http://www.manortron...ro-Fix-NMS.html

That would also have the benefit of being easier to use on several telescopes.

I would like to redo the mount in better wood. The current set up is okay for me but a bit high for my wife and it's a step ladder job for the children - such is the effect of the f6.4 I guess but I know ultralightweight options lower the height. In the long term I would like to completely redo the scope, so I may get the new ATM book:

http://www.scsastro....-telescopes.htm

and start planning something much more transportable and compact.