Sky Watcher 100 ED PRO Drawtube Thread Specs

[graemesmith]

Hi all,

I'm trying to use my Meade SCT accessories (I've got a lot of them) with a Sky Watcher Evostar 100 ED Pro.  I want to screw an adapter directly onto the drawtube and then screw my SCT stuff onto that.  Trawling the net gives me many variations on what the draw tube thread is but I'd like a definitive answer if any one has one!

Basically the adapter should be a M54 (or whatever the correct thread is) female to SCT male.  The SCT end is 2" but at 1mm pitch.  A standard 2" accessory is 0.75mm I think although I stand to be corrected on everything I've said so far.

I can get various combinations and piggyback them but I'd really prefer just the one adapter.

If anyone has any info that can help me I'd be grateful.

[Richard Thomas]

No idea about the pitch on the SCT thread but you're spot on with the 100ed thread being M54

[Merlin66]

The standard SCT thread is a 2" x 24 tpi.

 

I had the same issue mounting a Meade flip mirror on my ED80.....

Ended up getting a special threaded adaptor machined.

 

 

Edited November 26, 2019 by Merlin66

[johninderby]

Would this do? I 5hink the drawtube is threaded M56.

https://www.ebay.com/itm/M56x0-75-female-to-SCT-male-thread-adapter/254148351542?hash=item3b2c6c1636:g:9WsAAOSwm1Vce6yB

Edited November 26, 2019 by johninderby

[Merlin66]

Yeah,

that looks like the one I had machined.....

[johninderby]

Although it is 0.75 pitch not 1mm think it should thread on. The skywatcher drawtube thread is a bit sloppy I think.

Edited November 26, 2019 by johninderby

[graemesmith]

In the end I realised that one of adaptors supplied with my LX200 was a 2inch push fit SCT threaded adaptor.  It is not a screw on solution but fits nicely into the 2” socket on the Sky Watcher so job done and at nil cost!  Almost unheard of in this hobby.....