# Crayford focusser for finder scope



## savarin (Aug 13, 2018)

Started with a bunch of these





to make a bunch of these




One of which was faced on both ends then squared on two sides then drilled for a 4mm shaft.
Then mounted off set in the 4 jaw but only using 3 of the jaws and bored out to just enter the side of the 4 mm hole.




It was then mounted between a pair of mandrels to turn off the surplus.




leaving this small curved part.
The 6mm angle has 4 x 10mm bearings that the focusser tube slides against.




These are then bolted to a small plate








A tube to hold the eyepiece is added




Then mounted to the finder scope tube




The 4mm stainless shaft moves the tube in and out by friction alone.


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## BaronJ (Aug 18, 2018)

Hi,

Nicely done.  Could do with some blacking to cut down reflections.


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## savarin (Aug 18, 2018)

The inside is fully blackened. I use artists Atelier carbon black, its the blackest black I've found to date.


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## rwm (Aug 18, 2018)

Very slick. Is there a way to adjust the fit of the tube or do you just have to get the diameter right?
Robert


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## dtsh (Aug 18, 2018)

Nice, now you have to make a dual speed crayford.


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## savarin (Aug 19, 2018)

I made this one to the exact size but did place a screw and pusher to press the shaft against the tube but in practice it hasnt been required.
I may make a dual speed for my bino when I get that far and will use three balls pressing on the main shaft held with a cone.
Turning the main shaft is the coarse feed and turning the cone is the fine feed utilising the three balls as a planetary gearbox/drive.
I made a simple test and it worked pretty well.


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## BaronJ (Aug 19, 2018)

> The inside is fully blackened. I use artists Atelier carbon black, its the blackest black I've found to date.



Thank you, I did wonder what you used.


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## savarin (Aug 19, 2018)

some results here
https://www.hobby-machinist.com/threads/80mm-long-focal-length-refractor.26212/page-3
post 77


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