DIY Cheshire Eyepiece

[kbrown]

Probably done million times before but I thought I'd model and 3D print a cheshire eyepiece for myself. I printed it in three sections: The cap with the peep hole can be pulled out and since it's 1.25" I could pop in my QHY5L-II with a small CCTV lens to inspect the scope on my laptop screen. The reticle at the other end of the tube is also removable. I printed it with a 0.25mm nozzle to make it less obstructive. Seems to work fairly well.

[kbrown]

Wow, what a difference. Just used my scope for the first time after collimating it with this plus a laser collimator. Once I got both agreeing with each other I called it job done. Now I'm getting nice round stars. I'm slightly oversampling (0.40"/px) so I guess my remaining issues are down to good seeing, balance and guiding performance. Still need to properly analyse my flats and investigate if I have unwanted tilt(s) in my imaging train.

Anyway, I've been having collimation problems ever since I took my scope apart for flocking and other improvements. The chesire eyepiece helped a lot to get the secondary mirror in the right place and orientation. Really happy how things have improved. Happy to share the STL if anyone wants to print one of these?

Edited February 21, 2020 by kbrown

[silverdb]

I just bought a 3D printer.  I've been building telescopes for 20 years and am looking for astronomy related projects to print on my new printer.  Are you willing to share the models for your cheshire eyepiece?

[kbrown]

5 hours ago, silverdb said:

I just bought a 3D printer.  I've been building telescopes for 20 years and am looking for astronomy related projects to print on my new printer.  Are you willing to share the models for your cheshire eyepiece?

Of course. I've attached the models here. You shouldn't need to use any supports if you print the "plug" and the "tube" upside down.

ChesireEyepiece.zip

[Chaz2b]

Another candidate for a separate 3D printing board? Nice design.

chaz

[kbrown]

Did some improvements on the main tube as I found it a bit fiddly to use. Now I can pop this into my 2" focuser without any adapters (still works with 1.25" focuser too). It also has flat flanges instead of angled ones so it's easier to secure flush against the focuser tube. The "plug" and the "reticle" are the same as before. STL files attached if you want to print one too...

ChesireEyepiece.zip

Edited August 31, 2020 by kbrown

[kimball wiggins]

i could not print the reticle. am i doing something wrong?

 

[kbrown]

3 hours ago, kimball wiggins said:

i could not print the reticle. am i doing something wrong?

 

Apologies. I should have said the reticle has very very thin walls (0.3mm) and I printed mine with a 0.25mm nozzle. I'll add a thicker version of it which should be printable with bigger nozzles but they'll be more obstructive.

Edited September 2, 2020 by kbrown

[Stub Mandrel]

3 hours ago, kimball wiggins said:

i could not print the reticle. am i doing something wrong?

 

There is a setting for printing walls thinner than the nozzle diameter in Cura, but I find results can be poor.

[kbrown]

18 minutes ago, kbrown said:

Apologies. I should have said the reticle has very very thin walls (0.3mm) and I printed mine with a 0.25mm nozzle. I'll add a thicker version of it which should be printable with bigger nozzles but they'll be more obstructive.

Here's a new zip file. I've added a thicker version of the reticle. Should be printable with a 0.4mm nozzle.

 

ChesireEyepiece.zip