Thread size question

[Shelster1973]

.....bit random and thought this would be the best forum to put thread (mod please move if needs be to more appropriate area).

Have decided to mod my finderscope that came with my Orion OTA so as to be able to use it as a guidescope.

What I am after is does anyone know what size the thread is that screws the objective eyepiece into the body of the finder scope?  Am wanting to make a threaded adaptor so as to be able to screw that into the body and then put my Lifecam VX-3000 onto that and use.  Opening on the cam is 26mm so this will sit proud of the adaptor.

Plan is to make the piece in work...unless there are some machining wizards on SGL who want to make a quick tenner ;-)

[Tinker1947]

The thread diameter on my Sky Watcher and Celetron Finder Scopes is 50mm but they have a diffrent thread pitch, i sourced a Adapter from Modern Astronomy will only screw into the Sky watcher Finder scope, Bernard at Modern Astronomy may be able to help, give him a phone call......

[Shelster1973]

Cheers,

Was confusing myself with the bit I need to mod....is the back eyepiece that has the cross hair in it.  A rough and ready measure puts it as 27mm o/d.  Will measure it properly in work tomorrow what I can lay my hands on some calipers.

Am guessing that as they are an American company will be looking at an imperial style of thread too.

Was wondering if I could make it out of poly plumbing fittings...but that will need some investigation

[Bizibilder]

The trouble is Astro related threads can be metric or imperial.  There are even commercial components that I have that mix both!  You may be lucky and find it is 26tpi which is just about close enough to 1mm (25.4 tpi) metric that the two can be persuaded to go together without too much cross threading.

[Shelster1973]

Just been looking and once I know details may get one 3d printed up depending on the cost.....

[Shelster1973]

Well...thought I would try and get th info from the horses mouth as it where...went and emailed Orion in the US and the following is the reply I got back

Thank you for contacting Orion.

I’m very sorry se don’t have the spec for that screw. It is likely metric. A good hardware store should be able to match the threads.

All the best.

That clears that up then......

Guess I will stick with working it out then.  Also need to find me someone who is good at converting pen 2D drawings into 3D models suitable for creating a 3D print...

[rob0971]

Is your finder a 30mm or 50mm? If its 50mm, why not just buy the adaptor from modern astronomy?

[Shelster1973]

Not sure they have teh specific adaptor in question.  The threaded part they may have but the part that fits into the webcam opening is smooth and does not have a thread on.  Was going to contact adhesive teh smotth parts together so that is a permanent attachemtn and just gets screwed on an d off when I want to change between guidecam and visual finding.