Help removing end of refractor tube (Stuffed focuser Pt 2)

[MortonH]

This is a sequel to my "Focuser is stuffed" thread...

So I decided I would get the Stellarvue 2.5" R&P focuser. Before ordering I exchanged a number of emails with Stellarvue as they wanted to make sure it would fit to my scope. Unfortunately I have been having some dramas...

After removing my current Crayford focuser there is a black metal "ring" at the end of the telescope tube. The Crayford focuser attaches to this ring with grub screws, but the R&P focuser needs to thread directly to the tube, meaning that the black ring needs to be removed. However, it won't budge.

Now it's quite possible I'm just not strong enough to remove it, but when I mentioned it to Stellarvue they suspected it may have been glued in place. I can't see obvious signs of glue, but it might be.

I tried removing the lens cell at the other end of the tube but that won't budge either (I thought I could buy a new focuser AND a tube). So currently I have no way to attach the R&P focuser. Luckily I haven't actually ordered it yet.

Any suggestions? Is there something I can spray on the tube to loosen the ring at the focuser end? Or do I need someone like Strongmanmike to twist it apart for me? :lol:

[Larryp]

Could you try immersing the end of the tube in very hot water? May soften the glue if it is glued. Would an oil filter tool allow you to get more leverage on it ?

[MortonH]

Hi Larry,

What's an oil filter tool?

It may be that leverage is part of the problem. I don't have big or strong hands!

[MortonH]

Just Googled it - might be useful. Thanks!

[dannat]

r u screwing it off..i had a dew shield i thought was treaded, tried for 2 days to unthread it only to realise it was a push/pull -had it off in 2 secs

[Kunama]

Just a guess Morton, but look very carefully for a tiny grubscrew on the inside of the tube adapter. Many OTAs have these hidden little gems holding them against unscrewing.
Just looked at the SV site and they show 3 options, screw-in, or 2 adapters depending on what the focuser goes on.

[mithrandir]

There's a thread Tip for stuck/tight threaded items. That mentions a tool called a "boa constrictor". http://boa-uk.com/ and Bunnings stock them.

[MortonH]

Thanks guys. Looks like a trip to Bunnings is in order.

[Steffen]

You have to find something that grips the tube without stressing it. On my AT 80ED I cannot get the focuser off if the tube rings are still on, for example.

Cheers
Steffen.

[MortonH]

I reckon the Boa Constrictor thing is the way to go. Possibly need two - one to grip the tube and one to grip the bit I'm trying to remove. Haven't made it to Bunnings yet unfortunately.

[gbeal]

Try the rubber mat, or in my case the old (or new of course) inner tube.
Place it on a firm bench surface, stand the tube on the rubber, with the offending ring on the rubber. Grip the tube with two hands and push towards the rubber, while turning.
Gary

[MortonH]

I bought two Boa Constrictor things tonight - tried them one at a time and together. Still no movement. Nightmare.