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  #21  
Old 28-08-2021, 11:12 PM
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Astrofriend (Lars)
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Today I did some more work on my implemention of a rack & pionen gear into the friction type focuser. I took apart the focuser and did some measurement how much space I have and what parts I can reuse. It's very limited space and will be difficult, but not impossible.

Here is what I did:

http://www.astrofriend.eu/astronomy/...-friction.html

/Lars
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  #22  
Old 06-09-2021, 08:01 PM
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Astrofriend (Lars)
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I continue with my attempt to build a 3D-printed 3" focuser. I have now made the CADs for the rack & pinion gears, started with the worm gear, make the focus shaft holder and the focus chassi. Lot of details left to solve.

Here is my document, see page 7 to 9:
http://www.astrofriend.eu/astronomy/...-friction.html

Maybe it will not work with enough precision, but it's exiting to do at least a prototype. I can always hand over the CADs to someone who has a metal 3D-printer.

/Lars
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  #23  
Old 07-09-2021, 02:08 PM
Pepper (Steve)
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Lars, have you looked at 3D resin printers? My brother just bought one and the detail is excellent. Seems alot more robust than a typical 3D printed part.
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  #24  
Old 07-09-2021, 09:11 PM
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Astrofriend (Lars)
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Hi Pepper,
I have watch them on YouTube and looks to very good. But in my case, if I need higher precision I think I do the prototypes with my printer and then hand it over to someone who has a deicated 3D-printer with high precision or even a metal printer.

What is the maximum size your brother can print with his resin printer ?

/Lars
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  #25  
Old 19-09-2021, 09:44 PM
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A second version of the design of the focus chassi, now with a flex joint to act as a hinge instead of the earlier sliding roller bearings.

http://www.astrofriend.eu/astronomy/...-friction.html

/Lars
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  #26  
Old 20-09-2021, 03:17 AM
Pepper (Steve)
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His current printer doesn’t have a huge print size. Can’t remember exactly but I know it was smaller than I required.
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  #27  
Old 20-09-2021, 03:34 AM
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Hi Pepper,
No problem, my 3D-printer can take 230 mm diameter and 280 mm high at center, almost twice the size that is needed.

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

/Lars
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  #28  
Old 30-04-2022, 02:16 AM
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I realized that I put too high demand on the 3D-printed plastic parts. Now I have changed the construction and use three push pull screws to move the focuser draw tube. At the same time I now don't need the extra gearbox. The screws itself is the drawbox. If I direct connect it to a 200 step stepper motor each step move the focuser 3.5 my (M4 screw). With the timing belt gears I can extend or reduce it. Less backlash with this construction.

Here is my drawings over the design:
http://www.astrofriend.eu/astronomy/...-friction.html

Lot of small details still to solve, but much easier now compare to the earlier design.

/Lars
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  #29  
Old 05-05-2022, 10:28 PM
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Today the roller bearings I orderad arrived. The are of a thin design, 6x12x4 mm. The diameter can't exceed 12 mm because of the narrow space inside the focuser.

http://www.astrofriend.eu/astronomy/...-friction.html

It's relly exiting when you can start assembling the parts, so far I'm really satisfaid over how good this part of the focuser work. Now I can proceed with the push pull rods, I have changed it from M4 to M3 to have a better resolution, about 2.5 my per step (without micro stepping).

/Lars
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  #30  
Old 16-05-2022, 10:08 PM
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Now I have 3D-printed more devices to my motor focus. I can start to assembling the different parts and see if they fit together. Looks very promissing to me.

Here are the last details:

http://www.astrofriend.eu/astronomy/...-friction.html

I must decide if I will use half step or full step mode drivers. Both have pros and cons.

/Lars
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  #31  
Old 22-05-2022, 08:50 PM
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Today I installed the puch pull screws for the focuser drawer tube. As always when going from theory to practise there will be some complications. I had to do the holder of the screws adjustable to have it center the nuts in the timing gears. But that was an easy task.

Have a look at the bottom of the page to see the progress:

http://www.astrofriend.eu/astronomy/...-friction.html

/Lars
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  #32  
Old 23-05-2022, 10:24 PM
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Nice work, Lars. I can see you have put a lot of thought into it and the stepper motor side of things to.
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  #33  
Old 17-09-2022, 06:12 PM
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Thanks Joshua,

During the summer I spend my time on the car and not very much progress on my astronomy projects.

Most of the nechanical on the foucser is today ready for a test. But the stepper motor isn't finished yet.

Latest progress:
http://www.astrofriend.eu/astronomy/...-friction.html

At the botton a link to the stepper motor driver project. A lot of new things to learn until I can manage this.

/Lars
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