I think I will try to print this for my C11 on first occasion..
The original idea was to print 4 segments, but then I realized 3 or even only 2 will be enough to produce usable diffraction pattern.
The flip segments will be fixed on the steel rope ø1 mm (purple), which will act as a flexible shaft, moved by DC motor.
It is a pity MyFocuserPro currently does not support mask.. Maybe one day it will :-)
EDIT:
It just occurred to me the steel rope could be used as a heater..
Last edited by bojan; 20-12-2023 at 01:22 PM.
Reason: addition
Purely aesthetically, I think the 3 segment design is best - im sure optically 2 would do the job just fine!
What would be cool is an integrated bahtinov mask + flat panel + scope cap.
You could make the 3 circles of the bahtinov mask slightly smaller, and integrate them into one ring, and have the front cap with 3 sub-apertures in it... Rotate the mask rim to the full right limit = sealed cap, rotate to the full left limit = 3 sub-aperture bahtinov mask.
A secondary motor to flip the whole thing out of the way once focus is achieved.
Weight could be a concern, but then on a C11, all your weight is at the rear of the scope anyway, adding a bit to the front wont necessarily hurt...
Thank you for reminding me of this project, I almost forgot about it
Yours is very interesting idea, I will think about it.. it may be doable to integrate diffraction masks into lid as frame, with motor to flip "mask / no-mask".
As to scope cap, I was thinking about larger one to cover this contraption.. but my 3D printer is a bit small for this (175x175mm), so something big like that must be printed in segments and assembled (glued) later.. and this may compromise the accuracy a bit... probably not enough to preventing it working as lid anyway.
Flats I usually take on the sky before sunset.. so flat panel is lower priority for me at the moment :-)
Anyway.. I started printing it right now.. when finished, and if it fits OK, I will put stl files here.
Last edited by bojan; 25-01-2024 at 03:10 PM.
Reason: new pictures
Well, it works OK... especially with brighter stars (I expected that).
Unfortunately, my original measurements were in error, so the ring turned out too small (~6mm..).. so I will have to print the whole thing again.
I also found suitable motors...
Control circuit will be simple DPDT relay with additional diodes and limit switches (like on attached schematic), or USB relay board (application works only with 32-bit windows, which is OK with me).
After some more experimenting, I changed the concept somewhat..
This mask has larger area (so diffraction spikes will be more prominent) and when not in use it fits under the original C11 lid.
During exposure, each half of the mask is folded around shaft inside dew cap.
I plan to add the end parts as well, to make the mask completely cover the aperture when used.. but a trouble adding those additional 8 slits and hinges may not be worth really..
Printing mechanicals.. Bracket for motor (with gearbox), mask hinge will be on the shaft ø2 mm, also visible on image.
I am still not entirely sure what the electricals will be like, motor needs only 1~1.2 V to rotate with acceptable speed, so there will be a need to regulate Supply voltage to that value.
Also, because of gearbox, the moment is pretty high, and I definitely don't want to crash the mask into C11 corrector plate.
So the limit switches will have to be very reliable and precisely adjusted.
I will do it with camshaft and ø1.5 mm pin, which will operate limit switches (hopefully realiably).
That new design is looking really good mate. I love it...
I'm looking at 3d printers to start tackling some small projects I have planned.. similar sort of things to this, and brackets to hold equipment to my scope/mount.
Any recommendations on a decent starter/intermediate 3d printer?
...Any recommendations on a decent starter/intermediate 3d printer?
Alex,
I don't know.. I built my own, more that 10 ago, and I still use it.
Have a look at ebay... Jaycar had a good one couple of years ago.
I think any will do, provided it has heated plate and filament motor next to printing head.. they are going for 400~500 AUD
