So, not all dovetails are created equal!

[alfingido]

I have just bought a Nester Evolution 6 and already have a Skywatcher Evostar 80ED DS Pro that I want to be able to put on the mount occasionally.

But, it appears Skywatcher dovetails mounting plates are different to Celestron, because the Skywatcher rattles about on the Evo saddle.

Its either one of two problems. 

First, even though the dovetails look the same size, the Skywatcher dovetail must have a different angle because it won't clamp tightly.

Or, there is isn't enough travel on the saddle clamp, which would explain why it doesn't clamp the dovetail properly, irrespective of the actual dovetail angle.

Does anyone have a Nester Evolution 6 or 8  and if so, how close do the saddle jaws get before they won't move anymore? Is there a way to get the jaws to move closer together.

And, does anyone have both these dovetails and if so, can they check the dovetail angle on both to see if they are the same? I am pretty sure the Skywatcher dovetail is at more of an angle than the Celestron, but I would have thought they should be the same.

Allan

[Ags]

Easy to verify the angle - measure the width of the dovetails on the mount side and scope side, and if these are in a different ratio (Skywatcher versus Celestron) then they have a different angle.

[alfingido]

Doh! Why didn't I think of that......

[alfingido]

Just measured. The angles appear the same, however, the Skywatcher dovetail is .5 mm narrower on the saddle side and about .5mm deeper. I wouldn't have thought such a small measurement would have any effect, but, it looks like the saddle clamps have very little movement past the Celestron dovetail dimensions.

Allan

[michael.h.f.wilkinson]

I have see some differences in Vixen style "standard" dimensions. My C8 from the mid 90s on a Vixen GP mount clearly has a wider dovetail than the APM 80, SolarMax-II 60 or the dovetail I had on the LS35

[triton1]

You could maybe by a sheet of .5mm steel(similar to what they make feeler gauges with)and use this as packing,we used this back when I was a toolmaker.You should be able to get it at a good engineering supplier.

[alfingido]

Thanks, I thought of packing it out a bit with something, I'll have a look around and see if I can get any thin sheets.

Its not a priority, I need a clear sky so I can actually set the new telescope up first as it is, then I will think about using the frac on it later.

Its just annoying that it didn't fit.

Allan