3D Printed Guider Scope Holder for Staradventurer Counterweight Shaft

[kbrown]

Inspired by an article I saw online a while back I thought I'd design and print a similar guider scope holder for my Skywatcher Staradventurer's counterweight shaft. It'll be RA guiding only but I'm hoping to at least improve the nasty periodic error it seems to suffer from. The holder accepts the standard Skywatcher finder scope shoe. 

I've put helicoil thread inserts in the holes for the locking screws so it should last a bit better. 

Only issue I have is the structural strength of it. I get layer separation if I tighten the butterfly screw too much. I'll print another one in another orientation to see if that's stronger / strong enough. 

Edited December 14, 2018 by kbrown

[vlaiv]

Interesting.

I do have one question - will it work as a guide scope?

Raising this question because I can't get my mind straight right now if there will be impact of it sitting on the opposite side. Both main scope and guider rotate in same direction, but mount moving ahead in RA on scope side will mean lagging behind on guide side (or will it?) - wonder if calibration is going to take care of that.

[kbrown]

1 minute ago, vlaiv said:

Interesting.

I do have one question - will it work as a guide scope?

Raising this question because I can't get my mind straight right now if there will be impact of it sitting on the opposite side. Both main scope and guider rotate in same direction, but mount moving ahead in RA on scope side will mean lagging behind on guide side (or will it?) - wonder if calibration is going to take care of that.

I'm sure it'll work as the calibration figures out which way it should do the corrections...

[vlaiv]

5 minutes ago, kbrown said:

I'm sure it'll work as the calibration figures out which way it should do the corrections...

Yes, you are right - it is rigid connection between the two (there better be ) - and going in circle - catching up is in opposite direction on sensor but in same direction along the circle.

[kbrown]

I'd rather have it at this end of the rod than on top of the scope as I'm already pushing the capabilities of this little tracker with all my gear attached.

[JamesF]

8 minutes ago, kbrown said:

I'd rather have it at this end of the rod than on top of the scope as I'm already pushing the capabilities of this little tracker with all my gear attached.

I think that's an interesting point that has occurred to me before now.  With this mount the possibility exists of putting useful kit on the "bottom" end of the mounting bracket to help balance the weight instead of just using a lump of steel.  All that's required are sufficiently rigid mountings.

James

[kbrown]

1 minute ago, JamesF said:

I think that's an interesting point that has occurred to me before now.  With this mount the possibility exists of putting useful kit on the "bottom" end of the mounting bracket to help balance the weight instead of just using a lump of steel.  All that's required are sufficiently rigid mountings.

James

Exactly. I remember someone here (thinking of) putting the battery there. Perfect counterweight and would serve a purpose.

[kbrown]

Bah. Don't think this design will hold up as is. Not 3D printed at least. No matter which way I print it, it will crack (layer separation) when I tighten the locking screw. 

Might have to thread the end of the rod and fasten it between two nuts or something... 

Edited December 16, 2018 by kbrown

[8472]

I've similarly repositioned my guidescope from a side by side position next to my camera, to the opposite counterweight end.

Difference being, I've done away with the counterweight bar and replaced it with an aluminium plate bolted to the L-bracket one end and guidescope on a custom made bracket the other.

As the guidescope is now at the other end, it doesn't now count towards the mount's payload (it's now the counterweight). As a result, my guided subs length has increased 67%.

If you can make it work, it's the best place to put a full sized finderguider on the Star Adventurer, given it's modest payload

[kbrown]

While I could just use my camera ball head attached on the free bolt on the L-bracket and make an adapter that would allow me to put the finder scope on it, I thought I'd explore my original idea a bit further. Mainly to see if I can overcome the challenges I've faced and learn something but also to keep the overall weight of the kit down. 

Here's a clamp style variation that seems to hold up a lot better than my original design. I printed it in two parts and glued them together. This allowed me to print them in orientation optimal to the structural stresses when in use. I can now tighten the M6 wingbolt quite hard and it's not crackling at all. It's also quite easy to roughly match the DEC angles between the primary and guide scope. 

 

 

[kbrown]

Due to someone requesting the STL files, I decided to attach them here. Happy printing. For maximum strength I recommend to print in this orientation and then superglue the parts together.

 

 

Edit: Oops... Looks like I uploaded an old version of the model so I deleted it. Will upload the correct one as soon as possible. Sorry!

Edited January 14, 2020 by kbrown
Mistake

[kbrown]

Here are the correct files...

SA_CounterWeightShoe.zip

[cbbella]

hi, thanks very much for the files.  could you tell me what your infill and shell count/perimiter settings were please, and also any links you might have for the inserts and nuts/screws you used, and also what method did you use to put the insert in - i.e. did you use a soldering iron to melt it in or another method

once again many thanks

Colin

Edited January 16, 2020 by cbbella

[kbrown]

I can't remember the slicer settings off top of my head for the infill and perimeter. I'll see if I can still find the files on my laptop when I get home. For the thread insert I bought V-Coil 04005 Thread Repair Kit (M3) and used it as instructed.

 

Cheers,

Kari

[cbbella]

ok thanks for that. i'll look that kit up and get it ordered

 

cheers

[knobby]

Great idea, I'd be worried about flexure though ... Could you make an additional clamp to go across the bar and finderscope mount to increase rigidity ?

[wormix]

Hi, interesting design - May look at something like this myself. 
 

Out of curiosity, what scope is that on your setup?

 

cheers

[kbrown]

1 hour ago, wormix said:

Out of curiosity, what scope is that on your setup?

 

cheers

Oh it's a DIY refractor I made some time ago. It's okay but I'm planning to improve it in the near future. More info here:

https://stargazerslounge.com/topic/319373-diy-refractor/