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Homage to Homemade Crayford Focusers

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55 replies to this topic

#51 Stub Mandrel

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Posted 20 September 2018 - 05:16 PM

I was inspired to see all this great work, so I thought I'd share a couple of my own Crayford focusers:

 

3D printed in PLA with aluminium running strips:

 
DSCN1118
 
Aluminium focuser for custom scope built around Skywatcher ED 66 lens cell:
 
DSCN0256
 
66ED (2)

 


Edited by Stub Mandrel, 20 September 2018 - 05:17 PM.

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#52 miak

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Posted 21 September 2018 - 01:45 PM

That aluminum one is quite nice! Don't see a lot of dual-speeds ATM focusers, how hard was it to get the balls in and aligned, and to get enough pressure (assuming you used ball bearings for it)?



#53 Stub Mandrel

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Posted 26 September 2018 - 04:02 PM

That aluminum one is quite nice! Don't see a lot of dual-speeds ATM focusers, how hard was it to get the balls in and aligned, and to get enough pressure (assuming you used ball bearings for it)?

Thanks!

 

The dual speed took a 3D-printed mock up and then a couple of cages and cups. The real problem was the secondary shaft, I tried turning a groove, that was too uneven. I ground a groove and that worked well, but kept loosing its tension - the balls were hammering the sharp corner of the groove.

 

In the end I found a conical stone and ground a round profile groove to match the balls and that worked much better (and keeps its setting). I used a very small roller thrust bearing to allow me to use plenty of tension.



#54 mikelab

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Posted 31 July 2019 - 11:49 AM

Here is a Crayford focuser that I 3D printed 3 years ago. First I designed it in SolidWorks and then printed it.

I also attached a pic of some of the other parts I printed and the finished

scope. The fork mount was laser cut out of Aluminum.

(and yes, the scale and numbers are also printed - raised up about .030")

 

The focuser is smooth as silk. it rides on a stainless steel shaft with internal Teflon tension adjusters.

IMG_0443.JPG IMG_0461.JPG IMG_0494.JPG


Edited by mikelab, 31 July 2019 - 04:49 PM.

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#55 brave_ulysses

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Posted 31 July 2019 - 08:45 PM

welcome, mikelab; great first post! looking forward to seeing your other projects



#56 brebisson

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Posted 08 October 2019 - 01:03 PM

Hello,

Just finished 2 small crayford focusser for some of my single pole scopes…
Used a 12mm thick cherry board and a cnc to machine the parts…
The bearings are 8mm outside diameter with 4mm inside diameter…
The drawtube is 34mm outside and had to use a lathe to grind the inside to the proper size ☹
I used a 5mm push screw with a spring loaded ball at the top. I brazed a bronze thumb nut on it to look nice and buried a nut in the “center part” of the focusser…
After gluing, I “shaped” the focusser (slightly visible in the last picture) as wedges (mostly to look nicer and to shed weight).
I used a 3mm knitting needle as a rod and used one of the little round cut by the CNC as the turn button.
Final product is 46g!

 

IMG_1616-copie.jpg

Cheers,
Cyrille


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