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My astronomy project:
EQ mount with no meridian flip


Making of an EQ mount with no meridian flip

Part I, Ideas

  1. Introduction
  2. First simple drawing of an idea
  3. What mount head to use?
  4. Base disc
  5. Arm details
  6. Twin telescope mount
  7. Azimutal angle trimmer
  8. Summary of the first ideas drawings

1: Introduction

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

Earlier when I only did my balcony observations I could only point the telescope at East. Then there was no problem with meridian flip. Now when my observatory come that long that I can start use it I need to think about meridian flip and what problems it cause. One big disadvantage is when doing astrophotography. When passing the meridian the telescope and camera flips upside down. And if there is during auto guiding more problems arise.

All this things can be handled, but if you don't have to do a meridian flip it would be much easier, like an old Celestron fork arm mount.

Note:
This is just ideas, not for sure I ever will built something like this. And if I'm do it it will be a low cost project.

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2: First simple drawing of an idea

I have read about other project with some idea how to solve the meridian flip problem, last time in Sky & Telescope.

Close but not exactly what I want.

All project I read about use a very long fork arm with a knee on it. A long arm can introduce weakness which I don't want. A shorter straight arm will offset the telescope relative the pier which is not good either. But I want it much more compact, then maybe in my case a better solution, at least I can fit it inside my observatory.

EQ mount pier arm

This is my first simple drawing of my idea. I can have a modified version of my EQ6 mount on top or some other mount head. With my 5" refractor I need about 0.6 meter clearance between center of DEC axis and the pier. It can be shorter if I add extra weight on front of the telescope. It's like a single arm fork but without a moving arm. I live in Sweden at +59 degrees latitude. The high latitude make the off-axis point come closer to the pier, about 0.3 meter in my case.

Just have to move the observatory house aside to center on the telescope's new position. My pier is low and the headroom in the observatory is enough I think to hold the arm above.

One good thing with this construction is that I can have two telescopes without counter balance weights. One telescope on each side of the arm. Maybe a 5" refractor and a 10" Newton, about 25 kilograms. Not very much more then the 5" refractor with counter balance weights alone.

I will do a better drawing when I know what mount head to use and have more details.

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3: What mount head to use?

The EQ6 mount is not constructed to hold two telescopes, one on each side of DEC-axis. It can be made but better if I can find a mount that's better fit to that. The only mount I can remember to have this was a Meade mount about five years ago, but can't find it anymore, maybe out of production. It was advertised as a three-function mount, alt AZ and Equatorial and.

The Losmandy mount is almost how I want to have it, but it don't have any motors:

The Discmount DM6 is similar and with motors but don't have the opportunity to have a telescope on each side of the DEC-axis:

The AZ-EQ6Goto have these capabilities:

For sure there are others, but can't remember any for the moment. Maybe at the end it's best to stay with the EQ6 mount, easy to find parts for and easy to rebuild compare to have some other odd construction. Other alternatives looks to be very expensive also.

If you don't have the machine tools or free time to do this you can maybe use one of this ready made parts:

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4: Base disc

The base disc that arm will be welded to I plan to also function as an Azimutal adjuster (for some strange reason the SketchUp tool didn't let me draw rounded corners of the holes).

Base disc

The elongated holes let the azimutal angle be adjusted +/- 5 degrees. Even the Latitude angle can be fine adjusted with the bolts that holds the disc to the pier.

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5: Arm details

I did some complements on the arm design, this is to hold an old EQ6 mount head.

Arm details

If not too long a rectangular steel tube with dimension 100x100x6mm should be enough I believe.

Pier and no mneridian arm

The arm with its disc plate will be bolted direct on the bolts of the pier.

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6: Twin telescope arm

With a non meridian flip mount it will be easy to have two telescopes, one on each side of the DEC axis.

Twin telescope arm

Telescopes can point at any direction in the sky without colliding with the mount, sorry for bad drawing.

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7: Azimutal angle trimmer

I need somewhere to adjust the Azimutal angle.

Azimutal angle trimmer

This is maybe not a perfect solution, but I doesn't need to adjust this angle very often. There will be another adjuster on the opposite side behind the arm.

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8: Summary of the first ideas drawings

When looking over the idea and the drawings I have made it don't feel totally wrong. Maybe that I don't have a work shop or the necessary tools. But if I reconstruct it a bit it could be more productions friendly. Water cut technic can let me have the profiles at any shape.

In the profiles there must be openings to keep the weight down.

There must be openings to let the cables run through the arm and disc plate.

What materials to choose:
Steel, aluminum or carbon fiber?

What mount head to choose:
Shall I stay with my EQ6 or try to find something else? I don't think there are many options here because all other head then EQ6 will be very expensive.

Shall I weld the disc plate and the arm together or shall I have the angle between them adjustable?

If you wonder, the drawings are made with SketchUp tool, a free simple tool to do 3D drawings with.

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