Starwave dew shield screw spinning

[MylesGibson]

I have an Altair Starwave 102ED-R which has been a great scope for me. However, a few weeks ago, I was packing it up and undone the screw that keeps the dew shield in place and now it just spins when I try and screw it back up again. It's not really a huge issue, I can kind of angle it so that it holds in the right place, but it isn't as tight as it used to be, and would be nice if I could remove the dew shield to fix it.

Is there any way of doing this without actually removing the objective lens? As I really don't want to do that and potentially mess up the alignment!

 

Edited November 18, 2020 by MylesGibson

[fifeskies]

I am not sure exactly how this screw fits and where (a photo would help)

If the screw hole is clear of any obstructions (ie lens cell) you can use a "tap" to rethread the hole to the next size up, just make sure the small amount of metal swarf does not fall into the scope.

Hold the OTA tube so the hole is at the bottom and use the "tap" pointing upwards and make several small cuts of thread and remove each time , rather than cutting all at once.

[MylesGibson]

@fifeskies my apologies, I thought the photo had uploaded but apparently not! It's there now.

Yes, I was thinking of using a "tap" to do this, but I'd need to remove the shield in order to do this. I don't particularly want to remove the lens though

[DaveL59]

Depending on the screw size (m3?) then tapping to next size up may involve drilling the hole out to the required size for the next tap up the range and also opening up the hole in the dew shield to accommodate the larger screw. Real risk there of swarf being left inside the OTA which would not be good. A smidge of grease on the drill/tap may catch most if you work slow and careful but no guarantee you'd catch everything.

You might try a nylon screw to replace the metal one, if lucky the manufacturing tolerance might get you a screw that is slightly oversize and would then bind to what thread is left in the OTA body.

Alternatively perhaps a non-metric screw might work if similar thread pitch and a touch oversize?

[MylesGibson]

@DaveL59 Thanks for that, but that would also involve removing the lens, as I don't want to drill into the actual scope body

[DaveL59]

ahh looking at the pic again the threaded hole is in the silver ring?

You could try a couple turns of ptfe tape around the screw, perhaps, to help it bind. Won't last long but might help. Or even something like the sticky-back teflon tape they use on sealing machines, a sliver inserted into the hole for the screw to act against:
https://www.amazon.co.uk/gp/product/B089F77XNJ/ref=ppx_yo_dt_b_asin_title_o07_s01?ie=UTF8&psc=1

or even onto the thread before re-inserting

The above is the ALT SloMo on a cheapo Celestron LT70-AZ and firmed up the slop in the thread giving a nice smooth movement.

I've taken to replacing screws on my gear with nylon thumbscrews these days to preserve the treaded ally. Doesn't look as plush but saves messing about and easier to swap a nylon screw than drill and re-tap etc. I did have to do that with the finder shoe on the TAL100RS as prev owner had already stripped the thread in the integrated bracket.

Edited November 18, 2020 by DaveL59

[fifeskies]

I am assuming the issue is that the dew shield slides back down at higher elevations without the lock screw

Perhaps you could use a releasable nylon cable tie to prevent that (wound round OTA just below the shield), they are available in very long lengths, hardly ideal and a bit of a faff to use , but maybe as a short term solution until you decide something more permanent

I use them for cable management

You can use 2 joined together if need be.

Edited November 18, 2020 by fifeskies

[MylesGibson]

@DaveL59 yeah, it's in the silver ring. And that's a good idea to beef the screw up a little bit! I'll give that a try!

@fifeskies that may work temporarily, but I'd need a new one each night otherwise I wouldn't get it back in its case!

[fifeskies]

1 minute ago, MylesGibson said:

that may work temporarily, but I'd need a new one each night otherwise I wouldn't get it back in its case!

No , the releasable ones simply remove when you press the trigger , so you take it off for re-use.

 

Releasing the trigger is actually easier when 2 are joined together though I don't really see why that is the case.

[MylesGibson]

1 minute ago, fifeskies said:

No , the releasable ones simply remove when you press the trigger , so you take it off for re-use.

 

Releasing the trigger is actually easier when 2 are joined together though I don't really see why that is the case.

Ahh, didn't see the word "releasable" in your original message! If beefing up the screw doesn't work, I'll give this a go!

[fifeskies]

A velcro strap might be easier