Motorised lens cap

[Wyvern]

Not sure if this is a bit of a gimmick project but decided to do it after I found a couple of leaves in the telescope after a night's imaging session which had left marks on the lens. it was a fun build though.

Parts needed:

3D printer or the ability to have parts printed
Nema 11 stepper with 5:1 planetary gearbox
Arduino
8825 Strpper controller.
100uf Capacitor
Cable

Motor Housing

Lens cover

assembled

The code for the arduino lives here https://github.com/wyvernp/Auto_lens_cover/tree/main

Wiring diagram

 

(credit https://www.instructables.com/Controll-a-Stepper-Motor-With-the-DRV8825/ )

To connect to the stepper from a windows PC launch powershell and use the following commands (substituting the correct com port)

$port= new-Object System.IO.Ports.SerialPort COM6,9600,None,8,one
$port.open()
$port.Write("c")
$port.Close()

I have created a basic VB.net app for opening and closing the lens cap

https://od.lk/d/NjJfMTk0NTg1MTdf/AstroUI.zip

Send o to open the cap and c to close.

And the finished result.

Wyvern

[Gina]

Nice one Wyvern ? 

[Wyvern]

Thanks Gina!

[Feock]

That is really very clever. In Cornwall with our maritime climate, our better seeing often does not start until after midnight, and imaging sessions go very late.. This looks like a useful project to pursue.

Would you be happy to share any of the 3d print related files?

 

Many Thanks

 

Ross

ps just built 3 Myfocuser2 units this weekend and now printing off boxes and brackets for these.

 

[Wyvern]

@feock

First of all thank you!

I absolutely can but they are specifically made for my William Optics GT81. Attached below.

https://od.lk/d/NjJfMTk0NDUwNDFf/Lens%20Cover%20v6.f3d

https://od.lk/d/NjJfMTk0NDUwNDBf/Lens%20motor%20housing%20v6.f3d

[Feock]

Thank you .. will convert them to stl in the morning and have a look..with a little shim they should fit my ED72...  with all this rain I have time to build stuff.   Ross

[MarkAR]

Nice work mate, glad it all came together in the end. ? 

[Wyvern]

Edit--

Added a downloadable vb.net app for controlling lens cap

[Gina]

I would like to do something like that for my lenses but I want to swap dew shield for a light tight lens cap and that isn't easy.  3D filaments are not opaque.  The idea would be to be able to switch to doing darks without going out to the observatory.  OTOH it isn't that much problem to walk the 20 yards to the obsy!! And the exercise is good for me.

[Wyvern]

Posted by: @Gina

I would like to do something like that for my lenses but I want to swap dew shield for a light tight lens cap and that isn't easy.  3D filaments are not opaque.  The idea would be to be able to switch to doing darks without going out to the observatory.  OTOH it isn't that much problem to walk the 20 yards to the obsy!! And the exercise is good for me.

It may be worth waiting for John to test the black3.0 paint, if that blocks the light then it may be the way to go. I also put a layer of self adhesive black felt on the underneath of the lens cap which helps. I tend to do my darks by taking the camera off and put it in the fridge with a cap on so haven't tried with the lens cap setup.

[Gina]

Posted by: @Wyvern

Posted by: @Gina

I would like to do something like that for my lenses but I want to swap dew shield for a light tight lens cap and that isn't easy.  3D filaments are not opaque.  The idea would be to be able to switch to doing darks without going out to the observatory.  OTOH it isn't that much problem to walk the 20 yards to the obsy!! And the exercise is good for me.

It may be worth waiting for John to test the black3.0 paint, if that blocks the light then it may be the way to go. I also put a layer of self adhesive black felt on the underneath of the lens cap which helps. I tend to do my darks by taking the camera off and put it in the fridge with a cap on so haven't tried with the lens cap setup.

Good idea Wyvern.  With opaque plastic I could leave the dew shields on and cap the open end like you have done.

 

[Feock]

@wyvern

Hi  I am printing your files up after having converted them to .stl from the fusion 360 format. Would you mind if I posted them up here on your thread?

 

Hope to get the lens cap built this weekend.

 

Thanks

Ross

[Wyvern]

@feock

No problem at all, feel free :)

[Feock]

STL files for 3d printing ... oops they are not an allowed file type... I can't upload them.. happy to email them to any one who wants them. Sorry Ross

[Feock]

Wyvern I have printed your design off, rather nice. Awaiting the geared NEMA11 motor but that should be here soon. I have fitted a small EL panel (12volts) inside the lenscap and that seems to have the benefit of making a better cap for darks and also the capacity to take lights.

I am flashing up an uno R3 for the code but I am having trouble reading your photo/schematic. I can see from the code that pins 2 is direction, pin 3 step there is a 3rd wire... is that the ground? or what pin on the UNO should it go to..

 

Thanks

Ross

 

ps seems to go to the enable pin on the stepper controller?

[Wyvern]

Ahh yes the schematic doesn't look so good. If you click on the credited link below it there's a great instructional site on how to wire up.