Maximum finderscope weight?

[Giles_B]

I've recently refashioned my homemade Starsense explorer mount so I can attach it to the standard finderscope shoe of my telescope. It now weights 480g, including the dovetail. Obviously this takes up the finder shoe, although I could buy one of those splitters that allows two or three other finding devices to share the same shoe.

While I don't doubt that the standard finderscope shoe on my VX10 is up to the current weight, I did wonder how much load you can get away with before you run into problems distorting the tube or otherwise wrecking your equipment. Obviously the answer will be different for different setups - my newtonian tube is aluminium so I'd guess it might be more prone to distortion than a steel tube newt or a closed refractor tube. Has anyone overloaded a finderscope shoe, or alternatively have you had some experience of one taking 'miraculous' loads?

Edited September 11, 2023 by Giles_B
grammar

[Carbon Brush]

I have seen newt tubes suffer cosmetic damage from enthusiastically over tightened finder foot retaining screws.
A great pity that oversize washers, star washers, nyloc nuts and the like have yet to become readily available components🤔
Then of course there are the filed out holes from 'not drilled in quite the right place' attempts.
The damage doesn't affect views though.
In scope balancing, heavy finders located a long way off axis need thinking about.

[bosun21]

I used a generic Synta shoe splitter from EBay on my 12” dobsonian to accommodate my 8x50 RACI and my Starsense unit. I actually bought the triple splitter to enable me to mount the Starsense unit in the centre position keeping the unit level with the azimuth axis and the RACI on the side nearest the focuser. This worked great but It would become loose after a month or two. I resolved this by using a good quality nyloc nut to secure the splitter to the scope. All working great now.

 

[NGC 1502]

If you’re a DIY type it’s simple to reinforce a finder mount with a metal plate inside the tube.

If you add accessories your OOUK tube can be balanced longitudinally within the tube rings. Radial balance can be sorted with counterweights.  Magnetic counterweights won’t work on the OO aluminium tube, but it’s surprising what velcro will hold!
 

[Giles_B]

Balance is not really a problem, sliding the scope forward or backwards in the rings is all it takes.

@NGC 1502 Any tips on where would you get a plate of the correct curvature to use for reinforcement?

[RT65CB-SWL]

Curved, crinkly, wavey washers, or whatever other name you call them, can be obtained  from dedicated fixings suppliers direct or places like Amazon or eBay.

If the curvature is to great an angle, I am sure that squeezing one in a vice until you have something close to the required curvature will suffice.

[NGC 1502]

10 hours ago, Giles_B said:

 

@NGC 1502 Any tips on where would you get a plate of the correct curvature to use for reinforcement?

It would need to be a DIY plate, cut from sheet metal.  I keep offcuts of metal, mostly aluminium as I’m often in my workshop  repairing stuff.  If you have a local metal merchants like I have, they keep offcuts from their work for sale.

Cut with tin snips, file off the sharp edges, drill necessary holes. Using a vice etc, bend to shape.

If you PM me your address, I could send a piece of sheet aluminium 75mm x 75mm, 1mm thick, with my compliments for you to make your own DIY plate.

Alternatively, make a cardboard template of the correct size, mark necessary hole positions, tell me the diameter of the telescope tube. Sent it and I’ll make a metal replica and return it, as a favour.  If it’s for the 10” OO scope in your equipment list, no need to specify tube diameter because I have the same scope as that😊

To all other SGL members, this is a one off job, otherwise I’ll be in full time production!!

[Giles_B]

That is a tremendously kind offer - well, two offers really - (and this sort of kindness is very much an SGL thing!).

I'm not going to waste your time though, because I think I will probably stick with a single finder for the time being - I tend to look for specific things that either need the starsense or a finderscope (depending on how lazy I'm feeling) or the telrad. It was really an idle interest about the reinforcing plate because of other projects (currently I'm planning to attach the old focuser from the OOUK VX10 to a Celestron 130Z and wondering if I'll need to reinforce the tube in some way). So really the info about how you manufactured a plate is all I need.

The offer is very much appreciated though