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Old 25-10-2021, 08:45 AM
Boozlefoot
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Alt-AZ Industrial Scale?

Have just been pondering (once all the other projects are completed) creating an Alt-Az for a larger DIY refractor. I think 2 of these rotary tables would lend themselves to the job with the right steppers. They are using 90 turns of the handwheel to 1 rev of the table.

Has anyone tried these in the past?

Seems a cost effective type of thing.

https://vevor.com.au/collections/rot...illing-machine
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Old 25-10-2021, 08:54 AM
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Probably no-one used those..

But I can see NO reason why they shouldn't work in principle.

The drawback could be they are not specifically designed for telescope, so perhaps you will find some position limitations..
Also, you will need two of them... and lots of details to fit the scope/ camera.. at the end of the day the cost effectiveness may be questionable.

So, IMO second hand EQ may be better suited for your/our purpose :-)
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Old 25-10-2021, 09:24 AM
Boozlefoot
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Looking toward a 154mm fl2250 wooden refractor, so the mount will have to be fairly substantial. I may even have to turn it into a fork mount depending on the final weight of the OTA. As for accuracy, I'm strictly a visual observer and this will probably be good enough for my tired old eyes. There are two reasons for not going down the second hand EQ route - the cost is beyond my meager means - the challenge and fun in building the beastie.

Last edited by Boozlefoot; 25-10-2021 at 11:04 AM. Reason: Size anomaly.
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Old 25-10-2021, 09:37 AM
JA
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Quote:
Originally Posted by Boozlefoot View Post
Has anyone tried these in the past?
I haven't used one, but I've come close. I bought a smaller precision rotary stage and thought about it after using it for other activities.

If you are up for a challenge and are using it for visual then it would be great as a very capable mount. I would use the one of the type you have pictured (subject to loading) to adjust the altitude and have it rotate on it base with a bearing of some sort, unless of course you want to also use another rotary table for azimuth, but whatever you do you'll want to offset the mounting somewhat to allow you to adjust things to reach near the zenith.

Best
JA

Last edited by JA; 25-10-2021 at 10:47 AM.
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Old 25-10-2021, 09:44 AM
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Quote:
Originally Posted by Boozlefoot View Post
Looking toward a 154mm f2250 wooden refractor, so the mount will have to be fairly substantial. I may even have to turn it into a fork mount depending on the final weight of the OTA. As for accuracy, I'm strictly a visual observer and this will probably be good enough for my tired old eyes. There are two reasons for not going down the second hand EQ route - the cost is beyond my meager means - the challenge and fun in building the beastie.
Well, you may want one of those for elevation:
https://vevor.com.au/products/7x5inc...6b9c6198&_ss=r
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Old 25-10-2021, 10:18 AM
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"Looking toward a 154mm f2250 wooden refractor, so the mount will have to be fairly substantial..."

If that's not a typo, great understatement on the mount! Fairly sure you'll have to have aviation lights on top though which may spoil things a little.

If you have the parts already, I'd think about making up a mockup pole, with weights attached to match the parts in roughly the right position. You can get a feel for where the balance is and how much/where the clearance you need on the mount/scope etc.
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Old 25-10-2021, 11:01 AM
Boozlefoot
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[QUOTE=bojan;1539319]Well, you may want one of those for elevation:

Bojan - My thoughts perzackly! Have been considering that, by the time I've cut and fettled the steel, it will easier and same cost to use one of those at that price. (Could use similar rotary table with inbuilt tilt mechanism, but its purely "manual tilt" and would be a bugger to adjust)

Mura - As you can see I'm rather into the more "bushy" end of the astronomy spectrum, as you can see from my 10" SCT push-to. Am converting this at the moment to motorised with CNC "stand alone pendant". (I'll probably use the same pendant to drive this Altaz project.) It once had a 12" newt on it with hotrod flames painted at the aperture instead of aviation lights I kept falling off the ladder though...............
And a definite yes for the mockup pole

JA - yes, I would be using two tables (1 for az), and am considering underslung fork mount to alleviate room for steppers, and possibly compensate for the OTA weight. Not overfussed about zenith, if I can't reach it.........

It's really good to have these replies to keep me considering the pro's and cons - keeping my feet on the ground. Some people would be "amused" to see my motley collection of optics, I prefer the unusual and older style of technology
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Old 25-10-2021, 12:57 PM
croweater (Richard)
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Hi Rod, I can't offer much but encouragement . JA and Bojan will be more use techwise but please do a thread on whatever you decide. Love other peoples projects.
Good luck and cheers Richard
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Old 03-11-2021, 01:11 PM
Boozlefoot
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Update

Just "for giggles" I got a smaller 3" table to hang my faithful 6"f8 moon newt on. Offset it on an old flange mount in the yard and Alt achieves full zenith. Focuser height more comfortable than the dob. The balance is quite acceptable, and with greased threads on the Az flange the offset provides just the right amount of tension. Will put a trendy handgrip/lever on the flange for Az adjustment rather than pushing the OTA. Left the dob side bearings on to store in the original dob mount in shed. Takes less than 3 minutes to setup and for under 100 coupons provides me with an affordable, stable platform.
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Old 03-11-2021, 01:19 PM
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Nice setup,

Personally, I think options like "a bit a plumber's pipe and a right angle" advice to setup a EQ mount on the fly is what makes this forum worthwhile.

Not to detract from how to get the best bit of kit for some seriously earned money of course...


Steve
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