Skywatcher Crayford focuser - how to replace thumbscrews?

[emadmoussa]

Generally I could do with SKy-watcher dual speed focuser - seems OK anyway - but  frankly I find the usage of thumbscrews quite off-putting, let alone impractical for big EPs and centered collimation. This is one of the reasons I immediately replaced the stock focuser on my 12" Flextube.

Is there a way around this? Some adapters that use compression rings instead?? I don't want to end up replacing the whole focuser because of a couple of thumbscrews - Or do I ?

Edited April 18, 2014 by emadmoussa

[itmo]

yes there are multiple adapters with compression rings. for example one which replaces taht one seen in the picture. The problem then becomes focuser travel. Atleast for me. I am in search of a 40mm extension to the focuser tube with M54x1 threads on both ends to bring stuff to focus. 

[Lonestar70]

Hi Emad,

This will do you just fine... it replaces the existing adaptor at the top of the draw tube.

http://www.modernastronomy.com/accessories.html

4th picture down.  2" low profile adaptor... also gives a bit more focuser travel

Hope this helps.

Best regards.

Sandy.

Edited April 18, 2014 by Lonestar70

[Moonshane]

just use nylon thumbscrews? very cheap on ebay. probably M4 or less likely M5

[rob0971]

Baader clicklock, do a clamp with the skywatcher thread on. They do T2, M56 threaded (celestron & SW), SCT, M68 & M84 threaded. Does your drawtube have any of these threads when you unscrew the current eyepiece holder? The width of the clicklock will also double as a extension piece as well.

[Lonestar70]

yes there are multiple adapters with compression rings. for example one which replaces taht one seen in the picture. The problem then becomes focuser travel. Atleast for me. I am in search of a 40mm extension to the focuser tube with M54x1 threads on both ends to bring stuff to focus. 

Hi Itmo,

Changing this adaptor to the low profile one should give a little more inward travel, often needed to allow focus with a DSLR.

What is it that you are focusing that requires a 40mm extension?

Best regards.

Sandy.

[Bizibilder]

I simply drilled and tapped a third thumbscrew hole - Three screws works much better than two ever did!

[itmo]

I am focusing for visual observation. Problem is that the standard 2" adapter would provide this extra 40mm but i cannot use it because the inner diameter of the nose of the tube is a bit below 2" , which leads to my barlows and filters hitting it. The skywatcher focuser is designed to be too short, and you need to use a 1.25" adapter or a 2" adapter to reach visual focus. This makes focusing cameras etc. easier since you can just remove the adapters. I just hate those adapters with thumb screws so I have a 2" to 1.25" compression ring adapter with 2" filter threads , and a m54->2" adapter for the focuser. What I now need to get the perfect solution is the 40mm focuser extension M54 to M54 so I can move the M54 -> 2" adapter a bit outwards so it is in the middle of the focuser travel. This way I will have a nice 2" tube with no obstructions which i can drop down to 1.25" with a single adapter. This will also give me the possibility to screw 2" filters into the 2" -> 1.25" adapter so I can use my 1.25" eyepieces and barlows without having to constantly move the filter. 

[Peter Drew]

I'll raise you one thumbscrew. I use 4 for heavy components, works like a 4 jaw. 

[Lonestar70]

I am focusing for visual observation. Problem is that the standard 2" adapter would provide this extra 40mm but i cannot use it because the inner diameter of the nose of the tube is a bit below 2" , which leads to my barlows and filters hitting it. The skywatcher focuser is designed to be too short, and you need to use a 1.25" adapter or a 2" adapter to reach visual focus. This makes focusing cameras etc. easier since you can just remove the adapters. I just hate those adapters with thumb screws so I have a 2" to 1.25" compression ring adapter with 2" filter threads , and a m54->2" adapter for the focuser. What I now need to get the perfect solution is the 40mm focuser extension M54 to M54 so I can move the M54 -> 2" adapter a bit outwards so it is in the middle of the focuser travel. This way I will have a nice 2" tube with no obstructions which i can drop down to 1.25" with a single adapter. This will also give me the possibility to screw 2" filters into the 2" -> 1.25" adapter so I can use my 1.25" eyepieces and barlows without having to constantly move the filter. 

Hi Itmo,

This is a long standing issue with the 200p.

The problem is that the inside dia of the standard black SW draw tube adaptor fitted to this scope is slightly less than 2"... the silver draw tube it'self  is over 2" inside dia.

The adaptor I linked to above will cure this problem as it has a proper 2" inside bore... meaning you can use your 40mm adaptor with it.

Just unscrew the existing adaptor and screw on the new one.

Hope this helps.

Best regards.

Sandy.

[RikM]

You can get 2" twist lock self centring adaptor that adds about 35mm extension and replaces the normal 2" thumbscrew extension. You still have the two thumbscrews on the focuser, but you only have to do them up once when you install the adaptor. I can't find a link at the moment though.

[itmo]

The problem is that i do not have a 40mm extension,except the one where the inner diameter is under 2" =) I need a 40mm optical length aluminium tube with M54x1 thread on both ends. I already asked a friend's friend (a metal shop owner..) if he is able to fabricate one for decent price. 

[emadmoussa]

I wonder if this will work...a 2"  coma corrector to live permanently in the focuser (the scope is f/4.5 and CC will probably be useful) + 2" to 1.25" adapter ...

Thinking something like this....

Revelation 2" to 1.25" adapter inside a Revelation Coma Corrector...

[matt_baker]

On 18/04/2014 at 12:54, Bizibilder said:

I simply drilled and tapped a third thumbscrew hole - Three screws works much better than two ever did!

Since I'm not very competent at doing this kind of work, could you elaborate how you went about doing it, without making a mess of it?

I'm wanting to add an extra thumbscrew on my 130PDS for rigidity

[wookie1965]

I used one of these for 1.25" eyepieces https://www.altairastro.com/altair-2-1.25-self-centering-eyepiece-adapter.html

and one of these to make my focuser dual focus.https://www.365astronomy.com/Lacerta-Dual-Speed-1-10-Microfocus-Upgrade-Kit-for-Skywatcher-Crayford-Focusers.html

The only 2" twist lock I found is one of these whether they work or not I dont know. https://www.omegon.eu/reduction-rings-adaptors/omegon-2-twist-lock-adapter/p,45635