Suggestions on how to mount new finder scope

[iborg (Philip)]

Hi


I have a new finder scope, but, it is longer than the old one. As a result, I will knock it with my head when I look through an eyepiece, if I mount it the same way.


I bought an 8" radius block, with (I believe) a Vixen dovetail from another Icer. In the attached picture of the radius block, there are three holes at each end. I measure the center to center distances as 251mm, 277mm and 25mm.



I intend to use this, but, am not sure what I need to buy to mount the finder.


I think replacing the dovetail with a Losmandy VUP14 will do the job
http://www.losmandy.com/v-series.html


If anybody is able to confirm that this is a good idea, I would appreciate that.


I would also appreciate it if anyone has a better idea!


Thank you for any suggestions.



Philip

[Steffen]

Does your scope already have the holes to accept the radius block? If so, I’d use it, so you don’t have to drill new holes into the OTA.

Unless the Vixen dovetail bar has a pair of tapped holes that fit the finder mounting shoe I’d take it off the radius block. The 25mm spaced holes on the radius block look like they might suit the finder shoe, but they don’t appear to be tapped. If you have enough clearance underneath the radius block you could use short bolts and nuts to attach the finder shoe to the radius block. Otherwise I’d drill and tap a pair of holes into the radius block to suit the finder shoe.

If the OTA doesn’t have holes for the radius block I would drill and tap two holes for the finder shoe to attach directly, rather than four holes for the radius block.

[iborg (Philip)]

Hi Steffan


The radius block will fit, I just have to get the right sized screws to install it.


You are correct that the 25mm holes have no thread, just holes, but, using them would mean that the finder sticks out to far again, or is too far forward to be usable.


As I don't know quite where I want to position the finder, I am reluctant to drill holes in the Vixen block. That is why I think I will buy the Losmandy VUP14. I would then be able to move the finder back and forth easily.



Philip

[Steffen]

Why would you want to use the Vixen or Losmandy bars at all, rather than mounting the finder shoe on the radius block directly? Is it to get additional height?

From my cross-eyed glancing at the Losmandy drawing it seems that no combination of holes would match the holes in the radius block anyway.

I’d drill and tap a pair of holes (or multiple pairs for flexibility) into the radius block and put the finder shoe on that.

[iborg (Philip)]

Hi Steffen


I hadn't thought of mounting the finder shoe to the radius block directly. I'll think about that. Still leaves me issue of how far along to put it. I'll have to set it up and fiddle a bit.



I need to confirm, but, the Losmandy VUP14 should fit on the radius block, using the slots at each end. Before buying, I would ask the supplier to check this.



Philip

[Steffen]

You’re right, it might just fit, at the outer edges of the outer slots, but there wouldn’t be a millimetre in it. Unfortunately, the drawing doesn’t give all necessary measurements to be sure. I’d check with the supplier (or someone here who has that bar), those Losmandy bars ain’t cheap.

It would give you a few options for mounting the finder shoe, and if it saves you having to drill holes then I’d say, go for it.

[iborg (Philip)]

That's the way I am leaning.


Your suggestion of using just the radius block has me wondering. I may ask if someone at work can put in a set of pilot holes, say 3mm. They have the equipment to do an accurate job, and I could then drill out and tap to the size I need. Mind you, I also need to check if there is clearance between the bottom and the optical tube. Or pilot holes in the dovetail I have?

[Steffen]

If you tap holes in the radius block you won’t need clearance underneath. Just use short countersunk M4 bolts (hint: they don’t carry them at Bunnings – M3, M5, M6, M8 but no M4).