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Skywatcher 200 Dob Focusser


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Hi, I’m looking for some advice with regard to replacing the focusser on my basic Skywatcher 200. I’ve tried renovating the existing one but when I use the very heavy 32mm panavision eyepiece the focus tube just gives way and so it’s impossible to focus. 
I’m thinking of investing in this:

https://www.firstlightoptics.com/skywatcher-focusers/dual-speed-crayford-1252-inch-focuser-for-skywatcher-explorer.html
 

Does anyone know if this will be a straight replacement and if it’s likely to improve my life?

 

Many thanks,

 

Mark

 

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You can normally adjust the resistance of the focus tube movement in most Crayford focusers. This is normally a screw (Allen key). Maybe a member with experience of this will chime in. If you are looking for a replacement, then for large heavy eyepieces you would be much better getting a rack and pinion focuser. They are much more accommodating for weight.

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If you use an Allen key and tighten up this screw just a little it will stop the focuser drawtube from sliding down under weight.

It is a balancing act to get the tightness of that screw just right so that it holds the weight but doesn’t make the focus knobs too stiff. Tiny adjustments are what you want.

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1 hour ago, CraigT82 said:

If you use an Allen key and tighten up this screw just a little it will stop the focuser drawtube from sliding down under weight.

It is a balancing act to get the tightness of that screw just right so that it holds the weight but doesn’t make the focus knobs too stiff. Tiny adjustments are what you want.

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Oh gosh, it seems obvious now you point that out. Thankyou very much. 
 

Thanks also for the other replies. Next up, cleaning the primary…….

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On 01/10/2022 at 12:31, markjord said:

Next up, cleaning the primary…….

I have been known to use a dishwasher with extra quantities of 'Get ya glasses sparking clean' additives 🙂 

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On 01/10/2022 at 21:58, Spile said:

I upgraded mine with a Lacerta dual speed. I am very happy with the result 

+1 for the Lacerta. I did the same on my 250mm Skyliner, and it made the small focus adjustments much easier.

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  • 4 weeks later...
On 05/10/2022 at 04:58, SthBohemia said:

I have been known to use a dishwasher with extra quantities of 'Get ya glasses sparking clean' additives 🙂 

Seriously? And it worked ok?

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4 minutes ago, cajen2 said:

Seriously? And it worked ok?

🙂 Yes.. Seriously! However, I have hand made all the mirrors I have ever subjected to such treatment from fully annealed pyrex with a thickness of 1/5 to 1/6 the major mirror diameter. Not sure how a lump of plate glass would standup to the ol' dishwasher treatment!

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20 minutes ago, SthBohemia said:

🙂 Yes.. Seriously! However, I have hand made all the mirrors I have ever subjected to such treatment from fully annealed pyrex with a thickness of 1/5 to 1/6 the major mirror diameter. Not sure how a lump of plate glass would standup to the ol' dishwasher treatment!

It'll probably depend on dT/dt ... If that is sufficiently low, should be OK.

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On 04/10/2022 at 22:58, SthBohemia said:

I have been known to use a dishwasher with extra quantities of 'Get ya glasses sparking clean' additives 🙂 

Considering how etched my cheap glassware looks after repeated trips through the dishwasher, I think I'll take a hard pass on doing that.

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Before on the left, after on the right.

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21 hours ago, Louis D said:

Considering how etched my cheap glassware looks after repeated trips through the dishwasher, I think I'll take a hard pass on doing that.

Ypu just need a dishwasher without the 'sandblaster' option!

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