Plastic choice for takumar 200 tube rings?

[Ratlet]

Just got a perusa mini and have had a good time printing some bits and pieces so far.

I would like to print some tube rings for my takumar 200mm lens as I'm moving to a dedicated astro camera.  I've found a reasonable STL to work from but the design mentions that it cracked as he printed it flat rather than vertical (makes sense, you want the layers to be perpendicular to the stress). 

This I can handle, but wanted to check the best choice for filament.  It's never going to get hot enough for pla to melt but perhaps petg might be a better choice.

I do plan to modify the design slightly by including imbeded nuts for clamping and attaching to the vixen dovetail.

STL attached below:

https://www.thingiverse.com/thing:4918789

[Dr_Ju_ju]

Personally, for "finished items", I'd use either ABS or, preferably PETG, both Prusa Prusament filaments.... 

[Elp]

Think abs or nylon are the best mechanically. If an astro cam is attached ask yourself would you trust a 3d print to secure this (I know many do). Personally I don't so I stick to metal rings.

Edited September 29, 2022 by Elp

[Ratlet]

20 minutes ago, Elp said:

Think abs or nylon are the best mechanically. If an astro cam is attached ask yourself would you trust a 3d print to secure this (I know many do). Personally I don't so I stick to metal rings.

Do you use a dedicated astro cam to image with the takumar?  Part of the reason I'm looking at this is because I'm struggling to find proper rings.

[Elp]

Think I tried it, but at the time left the Takumar on the DSLR and a Samyang on the astro cam. What size rings are you after, you have a couple of options:

1. Get the adjustable 3 screw double ring type which typically comes with finder/guide scopes, this is a bit of a fiddly way of doing it but provides you scope for accomodating a variety of diameters. Can hold the lens or the camera.

2. Get rings to clamp onto the OD of the camera. I've got two different diameter ones, one of which I repurposed from my WO scope, in order to use that one with one specific camera I ordered some o rings to fit around the eos lens adaptor thus increasing its diameter and it now clamps tight.

3. I assume it's an m42 takumar. If you were to utilise Eos lens adaptors you could get the filter drawers or lens adaptors and clamp around them. This has the added benefit of keeping any filters enclosed and away from stray light hitting it at angles if they were mounted on the front of the lens.

Edited September 29, 2022 by Elp

[Ratlet]

7 minutes ago, Elp said:

Think I tried it, but at the time left the Takumar on the DSLR and a Samyang on the astro cam. What size rings are you after, you have a couple of options:

1. Get the adjustable 3 screw double ring type which typically comes with finder/guide scopes, this is a bit of a fiddly way of doing it but provides you scope for accomodating a variety of diameters. Can hold the lens or the camera.

2. Get rings to clamp onto the OD of the camera. I've got two different diameter ones, one of which I repurposed from my WO scope, in order to use that one with one specific camera I ordered some o rings to fit around the eos lens adaptor thus increasing its diameter and it now clamps tight.

3. I assume it's an m42 takumar. If you were to utilise Eos lens adaptors you could get the filter drawers or lens adaptors and clamp around them. This has the added benefit of keeping any filters enclosed and away from stray light hitting it at angles if they were mounted on the front of the lens.

I've been using one of the adjustable 3 screw ones with my DSLR, mostly just to keep it lined up correctly.  I'd discounted that for the dedicated camera as I had visions of the whole lot sliding out and landing on the floor, but then I guess you use those rings to mount a guide scope so there isn't much of a difference.

I do have an Eos extension with filter drawer on its way.  I'll see what other opportunities that presents for mounting when it turns up.

 

[Elp]

I think it's wise to devise a way of putting a physical stop behind the camera, maybe one in front too for reassurance. With the Samyang being a heavy beast mine once slipped a little whilst I was configuring it but luckily it moved slightly. So now I tend to use some long screws on the cheese plates I mount them to around any nooks to act as stops.