DIY 16" binoscope

[daz]

Not going to Kelling by any chance??

I could see a mile-long queue forming!!!

[keith5700]

No, won't be going to Kelling. Looks like a long way from Derby, presume that's the Norfolk one?

Not done much on the scope over summer, been spending time in the garden.

Still trying to persuade my mate to buy a couple of Ethos 8mm eyepieces. Be nice if we could borrow one first though, £900 is a major expense if it wasn't anything short of amazing.

Done a write up for Astronomy Now magazine. Hopefully it'll appear later this year.

[runoffshed]

Truly inspirational. Can't get over the quality of the secondary mounts....and in fact everything else! I am amazed the mechanicals have only cost about £500 so far.

You've got to find that extra £4000!

Good luck

John

Ps. Personally, I would like to see more use made of badly sawn plywood - like all my projects)

[albedo0.39]

Man alive Keith... that is EPIC ! - Well done to your engineering skills. I salute you.

[delsix]

I must agree with the consensus on this thread, this is an epic build. I take my hat of to you sir.

[keith5700]

Sorry, didn't notice recent replies on this thread.

I've put in a fair amount of work on the scope in the last couple of months, but most of it has been improving the workings of it, as we have a bit of viewing experience under our belts now.

We have just bought a Celestron Neximage, so are playing with that at the moment.

The first thing which became obvious was the need for some sort of motor tracking system.

I had a look round the shed and found a few motors and bits and bobs and desiged a drive around them. I cut a 12" wormgear on the lathe last week and split that into 2 useable segments for the alt and az drives. I would like some stepper motor drives on it, but haven't had time to get my head round what's required to get them to work yet. It looks a bit tricky with controllers and drivers and programming etc.

I'm just going with the 12v dc motors I've got, at the moment.

I've replaced the 2" wheels with 3" to make it easier to push around the patio, and fitted a steering rod to 2 wheels, as trying to get 4 wheels to track properly was a nightmare.

I'll get some pics up if I finish it this weekend.

[Paul Riley]

I really cannot comment on that device,other than holy s##t!

[keith5700]

Right, got a few pics of progress.

Although it looks quite, it shows the pitfalls of not designing something first, ie. I made the tracking bits as I went along and it's starting to look a bit messy.

I cut the wormwheel segments on the lathe first and tried to fit them in suitable positions, but as I went along, bits were getting in the way and some items have odd cutouts or spacers in them to clear other bits.

The steering bar was added to 2 of the wheels as it was nearly impossible to steer 4 independant wheels before. It's dead easy now and is a worthwhile addition.

I have been asked why 4 wheels and not 3. Well 3 wheels would have to have been much further out to get the same stability and would have got in the way of the user's feet. Also it wouldn't fit through the garage door with 3 legs.

[George]

Im gobsmacked with the machining that's been involved creating that:eek:

Do you have your very own CnC?

[Beyond_Vision]

Really awe inspiring stuff, what size single tube scope would it be equivalent to in terms of resolution?

I saw a 12" over the shoulder design at Kelling a couple of years ago and that looked pretty awesome but this blows it away.

Regards

Kevin

[astroimpulse]

Words fail me.

Simply brilliant.

[Jaffa007]

Some serious macheing going on there!!!

[Polar Bear]

Wonderful conception, design and engineering. Really inspiring work Keith

[keith5700]

Thanks for the comments, again.

I should mention that the motor/gearboxes are only temporary. I'm still trying to get my head round how to get a stepper motor to rotate at different speeds. It seems a simple enough task but but I'm lost in controllers and drivers and Arduino boards at the moment.

George, no I haven't got access to CNC, it's all done manually on my Bridgeport miller.

Kevin, I think the resolution is the same as a single 16" mirror. I don't think you can take account of the spacing between the mirrors to increase the resolution if each eye is only seeing light from one mirror. That's my theory anyway.

Electric focusser next, I'm drawing this up first so might look a bit neater.

Cheers for now.

[Altair40]

I'd never even heard of a binoscope until I saw that beast. You are to be congratulated. A lot!

Stick some actutators on it and get it to walk out of the garage on it's own! (Joke).

Wow!

I've looked at grinding my own mirrors for something as mundane as an eight inch newt but there seems to be no price difference from buying a factory built newt. I'll read some more.

As for the 130mm I have now - it's very well designed and from what I can work out, cheaper than it's component parts.

Maybe the tradeoff works better for a big dob? I'll start another thread on this - don't want to steal your light!

I'm a technician in a uni and might be able to gain permission to use our Myford Super 7 lathe for this sort of thing. If only to improve my skills in my own time. I'm basics only, I've never cut thread. There's a few other machine tools around in the workshop such as diamond and band saws plus a pillar drill that could be used for end milling at a pinch.

I've done a lot of wear work and grinding and polishing for spec prep but never a mirror. 20nm RA, yes. In a parabola, no.

Edited December 8, 2010 by Altair40

[Shibby]

Keith, this is insane - in a good way! I'm humbled by the dedication and skill you've put into the project.

One of my favourite features is definitely the programmable user settings - sheer class

[Coco]

Hi keith, ive decided the way forward for me in my obs is a mast like yours (or saw the shed down) is this a pre bought linear bearing or have you made it yourself?

Thanks

[keith5700]

Guy, the bearings are thick PTFE pads held in ally holders. Each holder is adjustable in and out to get the square tube running concentric to the outer round tube, and to adjust the preload of the pads.

The square tube is 60mm stainless.

An easier way would be to run the tube directly on to the outer race of some ball bearings.You'd have to use them in pairs with a spacer, so you'd need 16 bearings.

40m o/d bearings would be ok. You could put eccentric bushes in the bearings to adjust the shaft position/preload.

The height adjustment is by a 20mm square threadform shaft, turned by a car seat gearmotor.

[keith5700]

Just got it all tidied up, and finished the electric focusser.

The drives seem to work fine, bearing in mind they are just being driven off a rubber belt at the moment.

Focusser works well too, it converts to manual by pulling out the pin.

Now to have a go at imaging Jupiter.

[zhgutas]

oh my... this looks like something from "transformers" . something really really awesome! absolutely magnificent piece of engineering.

Marius

[ollypenrice]

Brilliant, Keith. I almost wish I still lived in Wirksworth so I could cadge a peep!

I'm interested in what you say about angling the EPs in a little since I was thinking about this recently. I have a good pair of small 10x25s for brding but can't get to use the two eyes at very close focus because the images won't combine properly in my brain. However, in another pair they will. So I wonder how binoculars are made and what the optical and neurological issues are.

Olly

Edited December 22, 2010 by ollypenrice

[keith5700]

Olly, the coning angle on my eyepieces was tried in order to make the viewing conditions more favourable. Making the optical focus point coincide with where the brain seems comfortable observing the image is just a theory I came up with, but it seems to work far better than having parallel eyepieces.

However, in your case, not being able to form a single image at all is nothing to do with any of this. I think you'll find the binocs just need collimating.

Cheers.

[Rob]

Great work. What a super piece of equipment I'd love to look through it.

Rob

[BinocularSky]

Keith:

Firstly, what a superb job!

Secondly, two questions:

Collimation? (as opposed to conditional alignment)

Thermals from the observer?

[keith5700]

Steve,

yes thermals are a bit of a problem when using high mags on planets. The fix is going to be some tubes at the top, with some sort of spiral deflector maybe, to route the thermals around the tubes and off at the top. It's not top of the list at the moment though.

Not sure what your other question is asking? it is vastly more difficult to collimate this scope properly, than a standard Newt. The extra mirror each side wasn't much of a problem.

The difficulty was getting both sides collimated, at the same time as getting the optical centre lines parallel to each other, and getting them parallel to the centre line of the centre ally tube. Or more specifically, to the centre of the axis on which the main mirrors travel up and down.

It did take days to get everything lined up properly, and I had to make several optical aids, multiple lasers and long bubble tube levels, etc.

It is possible to form a single image when both sides are not quite parallel, by simply tweaking one of the secondary mirrors. I can only assume the plywood versions of this design rely on constant adjustment when used by multiple observers.

Certainly I would say now that perfect collimation/alignment has been the most difficult part of the project so far. But on the flip side, with it being all ally,and very rigid, I will never have to do it again. Unless I drop it.