DIY - OAG

[fwm891]

Very neat set-up

[RobH]

Finally....an OAG with a focuser....no more faffing round in the dark with tiny little screws!! Well done, a great build...it can obviously be done as you've proven, now isn't it about time for commercial manufacture of OAG's with focusers, or even small add-on focusers for existing OAG's?

Cheers

Rob

[Merlin66]

Comes down to cost.....

You can add a small helical adaptor from Baader to do the job very well.

(#2458125) or the Telescope Service focuser TST2Vvar (with locking ring)

[RobH]

I'd be happy to pay the extra cost to have an OAG with a focuser Ken....thanks for the link, I'll check that out

Cheers

Rob

[Merlin66]

Slightly OT, but one of the best OAG/ flip mirror set-up I have is a "No name" version which has a sliding mirror and a helical focuser as well as a rotating section to orientate the camera. You can slide the mirror all the way in and it's a flip mirror or just slide it in enough to pick up a guide star - neat!

never seen the idea replicated by the "big boys" - I have some photos if there's any interest.

[michael.h.f.wilkinson]

Slightly OT, but one of the best OAG/ flip mirror set-up I have is a "No name" version which has a sliding mirror and a helical focuser as well as a rotating section to orientate the camera. You can slide the mirror all the way in and it's a flip mirror or just slide it in enough to pick up a guide star - neat!

never seen the idea replicated by the "big boys" - I have some photos if there's any interest.

There is interest;)

[fwm891]

Rob, Merlin, Michael - thanks again for the interest.

I've just added a small rotator for the QHY5 so I can orientate its CCD pixel row/columns with the NSEW motion of the scope. Nothing to see, it sits inside the T threaded section at the front of the QHY5 and locks against the top of the little crayford.

Francis

[Merlin66]

I'll look out the photo's and upload them......

[Merlin66]

Hopefully the images are self explanatory...

The slide on the side moves a full sized mirror up and down.

The large aluminium knurled ring is the guider focuser.

A T thread adaptor for the camera....

Any questions, let me know.

[fwm891]

Got my 383L back today so put everything together ready for use

OAG, SX usb Filter wheel and Atik 383L plus. Just need to re-balance the scope now. What's next...

[Gina]

OK I'll bite How about putting it on the scope and getting it working?

Looks great

[fwm891]

Its on there now Gina and gathering photon as I type...

If I could get PHD to stabilise I'd be very happy:mad:

[Merlin66]

Any update on this project?

I think the prism tilt is a feature worth follow-up.

[fwm891]

Hi Merlin66 - I've been using the OAG for a few weeks now and find it a real pleasure to use. Prism rotation is great and once set doesn't need further adjustment so I could probably have got away with a simpler rotation stage instead of the worm/wheel adjuster fitted.

The little crayford focuser works very well.

One small change I might make is to add a focus lock screw to the crayford. I don't leave the camera/OAG unit in the obsy so connecting disconnecting cables can alter the focus slightly, a lock would maintain the guider's focus and it would only be necessary to focus the main camera each night as in use I've found the focus on the guider follows the main camera precisely.

For me this has been a great little project - what's next...

[ncjunk]

Just found this thread and what a great bit of machining.

Is there anything you haven't tinkered with? Looks great ;-)

Enviado desde mi GT-I9003 usando Tapatalk

[fwm891]

Thanks Neil,

I'll try most things I can fit (somehow!) onto my small lathe - I enjoy a challenge and it keeps costs down a little...

[jimao22]

Hi,

Inspired by this great thread, I begun to do the same thing. An OAG home-made, with control over the prism. A good project is hard to be beat and I started with the idea to copy this project. I've got a prism 12x12 mm and some aluminium and brass bars.

The project was made in SolidWorks - it was a good opportunity for me to exercise on this software.

[jimao22]

Using my brand-new lathe and milling machine (WABECO), I made the main body of the OAG.

[jimao22]

It fits perfect on the MOONLITE focuser of my telescope.

[jimao22]

Next I made the prism prop. It was a real challenge, I did not work on a milling machine ever and the configuration of this part is a bit complex (at least for my skills), so I did it twice.

But the real problem was to find a worm gear to fit on dimensions.

By dismantle some old printers an scanners, I found a beauty of gear, a bit to long but good enough for the purpose. The gear belong to a stepper motor who "died" for a good cause.

For now, here is what I have.

[fwm891]

Jimao22 - nice build. might improve contrast if you blacken the sides of the prism. The prism I used also had a reflective and blackened hypotenuse surface. I now use a Lodestar B&W guide camera and I don't think I've had a FoV that didn't have a star that could be used for guiding.

[Gina]

Hi Francis

As you know, I now have the same scope with the same focuser but not had a chance to use it yet or even do much setting up. I've bought the relatively cheap OAG from FLO which is well made but rather lacking in facilities. I looked at the Atik OAG (much more expensive) since I have an Atik wheel but apart from having a guide cam focuser, has other deficiencies, which I thought pretty poor for them and the price.

The OAG I've got has no focuser other than a sliding oval shaped piece that carries the guide cam with an Allen grub screw to hold it. Been trying it by daylight on the scope with QHY5 but have got absolutely nowhere. The best image I can get from the QHY5 and QGVideo software shows just a few specks of dust on the sensor cover I focused the scope on a distant view and set the guide focus about right by measurement. I then tried moving it in and out as finely as I could manage but try as I might couldn't get an image - just a light grey blank image with dust bunnies! There is an inner ring with T2 thread to go into the filter wheel with 3 slots for the light tube, giving just 3 positions for the guide tube and cam. This limits the guide cam position and I don't think I can get the cam in far enough without hitting the FW. It may be that focus is further in and that's why I can't get an image.

The hole the light goes through to the QHY5 is just under 6mm and the prism is 6mm wide. The result is a circular disc image a bit less than the width of the QHY5 frame. I guess this is just about adequate.

All this leads me to attempt my own home made OAG.

What with this and several other requirements for turned items (pulleys etc.) I've be looking into small lathes (hobby lathes). When I looked some time ago they seemed to be about a grand but now I've found a few around £500 that seem to do what I would want. These include thread cutting. Do you have any recommendations on a lathe Francis?

[fwm891]

Gina - trying to stick inside your price range:

http://www.axminster.co.uk/axminster-sieg-c1-micro-lathe-mk2-prod33289/

http://www.chestermachinetools.com/conquest-lathe-3965-p.asp - good little lathe Chester look as though they have a sale on ATM

http://www.warco.co.uk/metal-lathes-metalworking-lathe-machine/302922-mini--hobby-lathe.html

You will also find lathes on ebay new/used. A lot of these small lathes are rebadged versions of the same basic chinese lathes

I like Axminster stuff but look at the Warco and Chester lathes first

[fwm891]

Gina - looked again at the Chester Conquest Super - http://www.chesterma...uper-3966-p.asp just within your price range and better than the one above.

One of these should be on you shopping list as it turns the lathe into a small milling machine: http://www.warco.co.uk/mini-lathe-accessories/302794-mini-lathe-vertical-slide.html

Look at the accessory pages for these lathes

I have an old Myford Speed 10, Myford are great lathes but tend to be pricy even secondhand (Myford's themselves have gone out of business but RDG Tools? hold Myford lathes and spares)

[Gina]

Thank you Francis Chester look the cheapest I've used Axminster for various tools and their quality is good - and I can pick things up when I go into Axminster for goat feed. Though in this case it's free delivery. I found the Warco one myself with a search. There's also a Draper badged one on Amazon which looks just the same as some of the others but costs a bit more.

I was looking at a very old one on ebay auctions with current offer of £60 with 5 days to go. No doubt the price will shoot up by then Anyway, I think I would rather go for a modern one with the extra facilities. I guess you can continue going up in price for the new ones adding this feature and that and also going up in size. I don't want a big one - I can't see me wanting to go above around 3" diameter or to turn a long shaft and AFAICS the circa £500 ones look quite suitable.