DIY equatorial platform

[Ratlet]

I'm in the process of designing one myself for 57°.  Is the issue that the platform would become very long?  It it possible for you to replace the south pivot with sectors instead to keep the length down?

[bosun21]

10 hours ago, Ratlet said:

I'm in the process of designing one myself for 57°.  Is the issue that the platform would become very long?  It it possible for you to replace the south pivot with sectors instead to keep the length down?

As far as I know the template for the platform wedges is what determines the working latitude for the platform. I don’t see how it can affect the actual length of the platform.

[Astronomist]

the bigger the diameter of the sector the further away from the south pivot the sector must be. And yes the south bearing is often replaced with a sector.

Edited September 17, 2023 by Astronomist

[Mandy D]

22 minutes ago, bosun21 said:

As far as I know the template for the platform wedges is what determines the working latitude for the platform. I don’t see how it can affect the actual length of the platform.

I was looking into getting an EQ platform some years ago and I discussed latitude with the vendor as I wished to move it between France and southern Spain at the time. IIRC, it was suggested that the platform be design for Spain, then a wedge fitted on it for use in France. The telescope would have to be secured to the wedge to prevent it from falling over when the wedge was in use.

[Ratlet]

16 minutes ago, bosun21 said:

As far as I know the template for the platform wedges is what determines the working latitude for the platform. I don’t see how it can affect the actual length of the platform.

The design of the platforms is largely determined by the scope COG (centre of gravity) and the latitude.  You are projecting a cone that passes through the centre of gravity of the scope (base + ota) and the latitude from the ground.  As the latitude decreases the pivot point position moves further away from the COG.  In a VNS platform the segments are basically the circular sections of the cone projected into a vertical section (to give an ellipse).

Taking a look at a design for a 10" Stellalyra (because I'm building one and have the COG and feet measurements) and designing for 28 degrees latitude, we can see that the Southen Pivot Point would be 850mm from the COG, which once turned into a platform would probably end up being over one meter long!  Not ideal...

The alternative would be to simply take another circle through the cone that is closer to the COG and make southern sections from this.

 

[bosun21]

31 minutes ago, Ratlet said:

The design of the platforms is largely determined by the scope COG (centre of gravity) and the latitude.  You are projecting a cone that passes through the centre of gravity of the scope (base + ota) and the latitude from the ground.  As the latitude decreases the pivot point position moves further away from the COG.  In a VNS platform the segments are basically the circular sections of the cone projected into a vertical section (to give an ellipse).

Taking a look at a design for a 10" Stellalyra (because I'm building one and have the COG and feet measurements) and designing for 28 degrees latitude, we can see that the Southen Pivot Point would be 850mm from the COG, which once turned into a platform would probably end up being over one meter long!  Not ideal...

The alternative would be to simply take another circle through the cone that is closer to the COG and make southern sections from this.

 

The one I had made by telescope maker David Lukehurst for my 12” works fantastic and even at the end of its travel is still safely balanced on the platform with no danger of falling over.