Design of a an adapter to 90 degree polar telescope

[Astrofriend (Lars)]

I already before used a 3D-printed adapter to attache a 90 degree viewer to a Star Adventurer's polar telescope. A big improvement, but still some need to get it better. This time I design my own adapter with the goal to make it much more stable.

Here is my project page with photos and information:

http://www.astrofriend.eu/3d-printin...r-adapter.html

With the indoor test I have done it looks very promising, much more stable now compared to the older one. If the later outdoor tests goes well I will put up STL files for download for you who find it interesting. It fit SkyWatchers EQ6, HEQ5, Star Adventurer polar scopes, maybe others as well.

Lars

[bojan]

Interesting :-)
Looking forward to final results.

[AstroViking (Steve)]

Definitely interested in this one, Lars. Especially if it will fit the Star Adventurer.

[Astrofriend (Lars)]

It should fit the Star Adventurer, I have sold that mount but can't see there is any difference of the polar scopes on my EQ6 and HEQ5. In the end it attache to the polar scope the diameter is 30 mm.

Still no clear night, it's Sweden !

Lars

[AstroViking (Steve)]

I just checked my SA's polar scope dimensions.

The knurled part at the end, which rotates to adjust focus has a diameter of 30mm.

The smooth, non-moving inner part has a diameter of 28.7mm (call it 29 for easier 3D modelling).

Cheers,
V.

[Astrofriend (Lars)]

Maybe only need a distance ring between. I don't think it's possible to 3D-print that thin device, will only be 0.6 mm thick. Maybe better to use some plastic film instead. Or is it just to tight the clamp harder ?

I have put up the STL file for download if you want to try. I can only test it on EQ6 and HEQ5 mounts and I don't had any clear sky yet.

Here you find the STL file:

http://www.astrofriend.eu/3d-printing/3dprinting.html

Let me know if it's possible to solve for the Star Adventurer mount.

Lars

[AstroViking (Steve)]

Hi Lars,

Or the user can put a layer of tape on the thin/inner part of the SA's polar scope.

I'll ask a friend with a 3D printer if he can make one for me and I'll let you know how it goes - and what needs to be done to make it work with the SA.

Cheers,
V.

[Max Vondel (Peter)]

A great idea. A sensible use of camera right angled view finder. I can never use the polar scopes as they are so uncomfortable and at horrible levels.

[AstroViking (Steve)]

Hi Lars,

I finally got my hands on the 3D printed adapter.

The good:
- my 90-degree view finder fits the adapter well. Not quite perfectly centred in the adapter, but close enough
- the design is good, and will make looking through the polar scope a LOT easier

The bad:
- Getting it past the focus knob on the Star Adventurer's polar scope is tricky. I had to pry the clamping ring open to get it on, and it is too loose to clamp onto the body of the polar scope. I trimmed about 0.5mm from one end of the clamping ring but that wasn't enough
- the bolt hole is too small for anything I can easily obtain down here. M3 is about the smallest bolt I can find. M2 is a trip to a dedicated bolt store, and even then it's a gamble.

Viking's suggestions:
- to get the adapter to clamp onto the body of the polar scope I had to fit 2 layers of tape, adding about 0.5mm to the radius
- instead of having the bolt running through the clamping ring, how about making the ends of the ring turn out by 90 degrees for about 5-8mm so that a larger bolt can be fitted

Regards,
V.

[Astrofriend (Lars)]

Hi Steve,
Great that you could print it out. It should fit (with a complemt with tape for the Star Adventurer). What I can see from the photos maybe the printer isn't so exact, maybe need a calibration. I must do the drawings to the actaul dimension, every printer will do it from perfect to far from perfect. There is always something to clean up or adjust after the printing.

The lock screw, drill the hole where the thread is to 2.4 mm, then thread it. Where the screw go through, drill to 3.2 mm.

The focus knob. You maybe have to opening the hole. I usually use a knive or something similar and rotate in the hole to take away material. Be careful to not hurt yourselfe.

It will center better after you clean up the debris after the 3D-printing process. In my case it fitted almost direct. I spent a lot of time to get the 3D-printer to print well. Still it could be better.

If you can calibrate the 3D-printer it will make it easier and you only have to do small adjustments afterwards.

It looks like it's printed with ABS filament, it's much more difficult to get good. PLA filament is much easier and make much better surface quality. But had other problems, sunlight isn't good. Nowadays I only use PLA filament, no sunshine in the night :-)

Maybe you can find something here:

http://www.astrofriend.eu/3d-printin...ter-setup.html


For EQ6 and HEQ5 it clamp around the telescope perfect I will say. But the Star Adventure for some reason the diameter is less than the focus knob. If I do the clamp with less diameter it will not pass over the focus knob at all.

Thank you for testing it out and the photos. A couple of friends (and I) has also tested it and it fit after some small adjustment, not as much as you did.

ps.
Do you use the Metric standard or the Inch in your country ?

Lars

[AstroViking (Steve)]

Hi Lars,

We use metric down here, although I usually find myself using a mixture of Imperial and metric measurements. Old habits die hard, as they say.

Compared to the other eyepiece to SA adapter I have, yours is a huge improvement. I'll clean it up a little bit and then leave it alone - it works well to hold the eyepiece and that's really all I need.

The quality of the printing is a bit disappointing - my friend's printer is usually a lot better than that. I must have the "Monday morning" print...

Cheers,
V.

[Astrofriend (Lars)]

I have fine adjust the dimension of the adapter a bit. The central hole is 2 mm bigger and the optical axis is moved 0.5 mm. There is a new STL file to download, version 1_5. This one I haven't 3D-printed yet. I used the old adapter and carved a bigger hole into it.

http://www.astrofriend.eu/3d-printin...r-adapter.html

Lars