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Homage to Homemade Crayford Focusers

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#1 opticsguy

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Posted 16 December 2016 - 02:23 PM

OK, no, I do not have a homemade Crayford focuser but am planning to build a 3 incher for next years 17" reflector telescope project and to hold my new 30mm ES 100 degree EP. So, am curious to see what others have designed and built and proud to show off here on the homage to Crayford thread.


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#2 dave brock

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Posted 16 December 2016 - 04:43 PM

I've made a number of these. There is Teflon under the grub screws pushing on 3 sides of the drive rod. Made without a lathe.

 

new pics 61.jpg

new pics 62.jpg

 

Dave


Edited by dave brock, 16 December 2016 - 04:44 PM.

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#3 coinboy1

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Posted 16 December 2016 - 05:42 PM

Dave, looks really sharp!! Great job!

#4 PaulEK

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Posted 16 December 2016 - 05:44 PM

Here's my very amateur 3-inch, motorized Crayford (actually the inner diameter is 2.7 inches). Made mostly from spare parts. The only thing I ordered were the four bearings. It actually works quite well.

 

post-46087-0-58907600-1416891935.jpg


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#5 mdsohio

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Posted 16 December 2016 - 07:46 PM

Can you snap a pic of the underside and directly from above Dave?
Mike

Edited by mdsohio, 16 December 2016 - 07:47 PM.


#6 Chucke

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Posted 16 December 2016 - 07:56 PM

Here is a motorized 3 1/4".  I have machine tools though.

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  • IMG_0938.jpg

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#7 Bob4BVM

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Posted 16 December 2016 - 08:26 PM

More on this in my reply to the "Long focus eyepiece" thread above, but here is my attempt at 3":

 

3" bore, ~8" travel, DT positioning measurably repeatable to a resolution of 1/10,000", ...

 

No real machine tools, just a wood lathe with x/y table & a drill press.

 

CS

Bob

 

IMG_4312s.jpg IMG_4313s.jpg


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#8 dave brock

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Posted 17 December 2016 - 01:07 AM

Can you snap a pic of the underside and directly from above Dave?
Mike

Sorry Mike I don't have the camera here at the moment and the focuser is on a scope so can't easily take those photos but the curved piece is hacksawed from an aluminium tube and the U shaped piece is from a box section and both are bolted to the base with countersunk machine screws. A bit of care is needed to position the curved piece but the bottom on the box piece can be sanded on a very slight angle to counteract a slight position error. The rest of the tension is adjusted with the horizontal grub screws.

 

Dave


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#9 Chriske

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Posted 17 December 2016 - 05:35 AM

folding-focuser-21.JPG


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#10 Chriske

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Posted 17 December 2016 - 05:35 AM

printsonian-tube-assembling33.JPG


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#11 Chriske

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Posted 17 December 2016 - 05:42 AM

One of our oldest concepts, resin casted.

 

Focuser30.jpg


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#12 opticsguy

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Posted 17 December 2016 - 10:10 AM

OP here.  Seeing some very nice equipment here and already thinking about my 3" build.  The 3d printer sure offers up some nice options.



#13 Pinbout

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Posted 17 December 2016 - 12:01 PM

folding-focuser-21.JPG

its not a crayford.... :p

 

but it is ****'ing awesome.


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#14 daviddecristoforo

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Posted 17 December 2016 - 12:24 PM

This is my one and only Crayford focuser made mostly of exotic woods.

 

IMG_3290.JPG


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#15 nebulasaurus

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Posted 17 December 2016 - 12:35 PM

This is my one and only Crayford focuser made mostly of exotic woods.

 

attachicon.gifIMG_3290.JPG

That is not a focuser - it is a work of art!

 

J.


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#16 mdsohio

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Posted 17 December 2016 - 12:54 PM

 

Can you snap a pic of the underside and directly from above Dave?
Mike

Sorry Mike I don't have the camera here at the moment and the focuser is on a scope so can't easily take those photos but the curved piece is hacksawed from an aluminium tube and the U shaped piece is from a box section and both are bolted to the base with countersunk machine screws. A bit of care is needed to position the curved piece but the bottom on the box piece can be sanded on a very slight angle to counteract a slight position error. The rest of the tension is adjusted with the horizontal grub screws.

 

Dave

 

Thanks Dave...that helps. Great focuser!

MIke



#17 Rusted

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Posted 17 December 2016 - 01:22 PM

At the completely opposite [barrel bottom] end of the quality scale: :lol:

Scrap bin sourced materials, 2" EP, long travel, all brass, refractor Crayford.

 

IMG_1883 rsz brass focuser.JPG

IMG_1880 rsz brass focuser.JPG

IMG_1875 rsz brass focuser.JPG

IMG_1878 rsz brass focuser.JPG

 

The pressure springs are inside the main tube and used threaded, bell-shaped, spring retaining nuts.

These automatically grip the inside of the spring without any slip.

The whole thing was very crudely made but an interesting exercise on my lathe.

I wanted something heavy to better balance my home made, all brass refractor.

Made for my home made 5" f/15 BK7/F2 achromat lens from the early 1980s.


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#18 Chucke

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Posted 17 December 2016 - 01:30 PM

Chriske,

 

Nice work on the hinged focuser.  I thought about making one once but decided it would be more work than I was interested in doing.  Is it 3D printed?


Edited by Chucke, 17 December 2016 - 01:30 PM.


#19 Chriske

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Posted 17 December 2016 - 01:55 PM

 

This is my one and only Crayford focuser made mostly of exotic woods.

 

attachicon.gifIMG_3290.JPG

That is not a focuser - it is a work of art!

 

J.

 

indeed...!!



#20 brebisson

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Posted 18 December 2016 - 03:38 AM

Hello,

 

Hopping that helicoidal Crayford do qualify as home made Crayford, here are 2 other entries. Contrary to most of the other posts here, they are for 1.25" focusers.

 

The focus of the construction were low profile, weight, cost and simplicity.

Althrough they ar enot able to carry heavy eyepeice, they do work very well, and at around $8 a pop, they are cheap. They are also very easy and fast to build (less than 1/2 hour a pop). At less than 1" height (actually, 2cm + whatever travel you want), they are also low profile (the pictures there are using a "test tube" which is 5cm total, longer than the 3.5 cm that I use once things are calibrated).

 

the 5° angle on the bearings give a 10 mm course on a full circle, which gives quite a lot of precision.

 

The first one is at the top of a single pole scope.

DSC_6373.JPG

 

The 2nd one is on a small 114, FL 500 scope.

DSC_6376.JPG

 

 

The hardest part of course is to get the aluminum tube correclty made (ie, concentric enough).

Cyrille


Edited by brebisson, 18 December 2016 - 04:55 AM.

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#21 Chriske

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Posted 18 December 2016 - 05:05 AM

Yep printed, the yellow one is not, that one is resin casted.

 

Chriske,

 

Nice work on the hinged focuser.  I thought about making one once but decided it would be more work than I was interested in doing.  Is it 3D printed?



#22 polaraligned

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Posted 19 December 2016 - 06:42 AM

The business end of my 6", f/15 refractor. 

 

DSCN5410.jpg


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#23 Chriske

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Posted 19 December 2016 - 06:47 AM

Anodizing...?



#24 polaraligned

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Posted 19 December 2016 - 03:08 PM

Not anodized.  I was going to have it brass plated, and my local guy quoted me a reasonable price, but then went out of business shortly thereafter.  I probably will send it out to get anodized when I get a chance.  I don't like leaving aluminum unprotected. 


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#25 Bob4BVM

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Posted 19 December 2016 - 04:33 PM

The business end of my 6", f/15 refractor. 

 

DSCN5410.jpg

Anodized or not, THAT is a work of art.  Touches the heart of this ATM like no plastic ever could.

 

Most of my DIY aluminum stuff is still bare, no real problems after many many years of use.  If I lived in a salt-air environment, that might be different. All of my fasteners and other non-aluminum parts are SS, so that helps avoid corrosion issues one might see with plated or (especially ! ) brass fasteners.

 

BTW I also see this focuser as a great design for an Astronomer's Beer Stein ! :)


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