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question about eq platform for dob

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#1 rfiol

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Posted 06 December 2021 - 11:40 AM

I'm designing an equatorial platform for my dob, and have decided to go with the VNS (Vertical North Segments) design.  My question is: Why not a VSS also?  I've yet to see a design with a vertical south segment.  Possible?  Practical?



#2 thoughtwave

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Posted 06 December 2021 - 07:58 PM

It should be exactly the same principle, just reverse the direction of the motor.



#3 Ed Jones

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Posted 06 December 2021 - 08:52 PM

I think he means both bearings would be vertical.  I think it would "float" and need constraining.



#4 Tom Stock

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Posted 06 December 2021 - 09:30 PM

I'm designing an equatorial platform for my dob, and have decided to go with the VNS (Vertical North Segments) design.  My question is: Why not a VSS also?  I've yet to see a design with a vertical south segment.  Possible?  Practical?

I believe it would just make the platform larger than it needs to be.



#5 rfiol

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Posted 07 December 2021 - 09:01 AM

I think it would "float" and need constraining.

Thanks, Ed.  This is what I was thinking, and it seems to be the only (albeit significant) downside.


Edited by rfiol, 07 December 2021 - 09:02 AM.


#6 Rodastro

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Posted 08 December 2021 - 05:18 PM

The club I belong to (Astronomical Society of Victoria) has an Instrument Making section and we’ve built I think about 15 platforms with two vertical sectors. Mark Justice runs the section and developed the design below. The top board is constrained by two bearings. The green rollers are conical and made to rough shape on a 3D printer. They are then spun with a drill while in position against a razor blade to smooth the surface.

 

The platform below is the only one we have made that has a second motor for limited dec adjustment. The second motor has a cam attached to it. This platform also has a hand pad. I’ve used it a few times and it works nicely. The hand pad is very helpful for high power viewing of planets.

 

As you can see the stepper motor drives both sectors which adds stability.

 

We made these platforms in batches of about 7 or 8. It would be a fair bit of work to make one on your own. We did it by dividing the tasks up. I did the bent laminations for the sectors, Mark did the electronics. Another member did some of the wood cutting, individual members assembled their own platforms from parts supplied. The assembly took place at a meeting where we could all assist each other.

 

Rod.

 

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#7 rfiol

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Posted 09 December 2021 - 09:18 AM

Awesome!  Great job!



#8 sw196060

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Posted 25 January 2022 - 11:40 AM

I like your design.

Can you show me closer detail on your levelling feet?

I am designing a platform and feel that the levelling feet may be the weak link in terms of stability from vibrations.

 

Thx.


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#9 Rodastro

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Posted 26 January 2022 - 04:08 AM

Hi Stan

 

Here are some pictures I hope help. The front feet are just plastic blocks that go under the rollers for the pole facing sector. 
 

The adjustable feet are stainless steel cup head bolts. They thread into tee nuts embedded in the bottom of the baseboard. Wing nuts are added and tightened against the tee nuts to make sure the bolts do not wobble. I saw this arrangement online on someone’s platform and it works well. You only need adjustment in the north south plane. In fact you can use just one adjustment bolt. I felt two was more stable. I bought some knobs on eBay and attached them to the end of the bolts.

 

Hope that answers your question.

 

Rod.

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Edited by Rodastro, 26 January 2022 - 04:11 AM.


#10 sw196060

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Posted 28 January 2022 - 10:24 AM

Hi Rod,

  Thanks for the info.  What size bolts are they?

I would assume maybe 1/2" bolts.  In my case I will add some feet to the bolt ends to keep the bolt heads from sinking into the soil.  I usually setup on the grass in my yard, or in a field.



#11 Rodastro

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Posted 28 January 2022 - 04:31 PM

Hi Stan

 

I used 10 mm bolts. I found the the cup heads on these bolts worked fine on grass.

 

Rod.


Edited by Rodastro, 28 January 2022 - 04:32 PM.


#12 Jehujones

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Posted 30 January 2022 - 10:39 PM

wow, that's really nice. those leveling feet are pretty fancy. mine look Neanderthal compared to that but I used huge 1/2" bolts so it would be easy to tighten the nuts without tools, especially if you have gloves on. I also like to set up on grass when I can.

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