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Focuser 'playing'


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I used my SW 150 today after 2-3 months of hibernation and noticed, for the first time, some stiffness when focusing and 'play' in the draw tube.

I haven't been aware of this before but today, rather than looking at a more distant star in the dark, I was looking at sunspots (using my newly received white light filter) - a target which I'm sure would tend to highlight any 'jump' or 'slip' as the focus wheel was turned.

My questions are:

Is this a known feature (failing?) of the focuser in my scope?

Is there any easy remedy, such as a touch of lube or similar, or something being tightened?

Is it worth considering replacing the focuser and, if so, what should I look for?

As ever, hoping to tap into the collective wisdom abounding in the forum (before I go and do something silly!) and grateful for any input/response.

In the interests of 'full disclosure', the scope has been kept comfortable, dust-free, warm and dry and spoken to reassuringly during its recent resting period ...

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Useful indeed! Thanks for that.

I've had a quick glance and it looks to be a comprehensive 'how to' procedure. I'll look more closely and see if my poor DIY abilities are up to the task.

Meantime, while trawling tinterweb for any info, I found an earlier SGL thread on the very subject of replacing the 150 focuser. Perhaps I should have tried a search here before posting my query. Anyhow, it seems I'm not alone in thinking that this focuser can be bettered.

Thanks again, Ronin.

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Thanks for taking the trouble to post, Wookie, but my 150P has a rack and pinion focuser and is not like the one in your clip.

Haven't had time to get into the innards of mine yet but I will try over the weekend (lots of rain forecast!).

Nevertheless, thanks again.

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Got stuck in today and, as I feared, there's not much I can modify to make the problem go away. It's simply that the draw tube is too loosely fitted inside the outer tube so that when the pinion wheel engages with the rack there is a slight back-and-fore slip. I can't think of a way to eliminate or even reduce this.

So it's off to hunt for a suitable replacement ...

Thanks for your responses to my query.

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Interesting thought, Lorne.

Had briefly thought of trying to paste on some thin cellophane round the inner barrel, from and to the rack. But I thought I'd probably end up with crushed and wrinkled cellophane 'gumming up' the works!

We'll see, though ... Never say die is perhaps the best approach.

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