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Author Topic: My scope focuser upgrade  (Read 428 times)

jscottb

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My scope focuser upgrade
« on: October 05, 2017, 06:53:55 PM »
I know a few here like visual astronomy as well as bots and 3d printing so here is my latest scope project.

It's the beginnings of a simple 2"/1.25" crayford style focuser. I also wanted a very low profile focuser that I could add or take rack length away at night during use. This is very useful with many larger mm ep's, 20mm and above.

It will be in four parts; The tube mount, the base, 2" focus rack and 1.25" ep adapter.

There will be one bearing on the base and one roller on the knob assembly with rubber o-rings to move the rack up and down and keep presser on it. I may opt to use some teflon in the tube and rack for smoother movement. I may just smooth sand the tube and rack and test the movement first.  Still a lot of holes and work to add :)

Here are a few images and a test print of the base.

Screen Shot 2017-10-05 at 6.21.03 PM.png
*Screen Shot 2017-10-05 at 6.21.03 PM.png (122.09 kB . 454x396 - viewed 61 times)
Screen Shot 2017-10-05 at 6.25.40 PM.png
*Screen Shot 2017-10-05 at 6.25.40 PM.png (96 kB . 402x390 - viewed 58 times)
20171005_182728.jpg
*20171005_182728.jpg (362.99 kB . 481x411 - viewed 58 times)
« Last Edit: October 05, 2017, 08:01:58 PM by jscottb »

jscottb

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Re: My scope focuser upgrade
« Reply #1 on: October 05, 2017, 10:37:05 PM »
I have mad it a bit more organic.



Looking next into tensioning points for the shafts and may use two bearings for more points of contact, but will try with one first. 
« Last Edit: October 05, 2017, 10:47:32 PM by jscottb »

jinx

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Re: My scope focuser upgrade
« Reply #2 on: October 06, 2017, 05:00:15 AM »
fine looking start Js, you using a roller for adjustment rather than a rack and pinion? just wondering where you lock it in place.
I build bots

jscottb

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Re: My scope focuser upgrade
« Reply #3 on: October 06, 2017, 07:47:22 AM »
Thanks Jinx.

Usually you have some sort of tensioner on the knob assembly and roller. That;s what I am sorting out now.
 

jscottb

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Re: My scope focuser upgrade
« Reply #4 on: October 07, 2017, 07:57:43 PM »
Well, my plans have changed... The "person" I won the 6" scope from was a twerp and wanted 140$US more for shipping after waiting four full days with no communication  >:(

I found  a dealer with new 130mm Orion optics in a bad shipped scope. Says the optics are unharmed and are under warrantee for 60days. This is what I wanted to do kind of anyway, but new good optics where more costly than the other scope. It will come with other parts as well.

I plan to print a mirror cell (if needed) a box and a focuser/secondary mount and truss the two together with aluminum L beams or square tubing.

Here is a first draft of the focuser and spider asm. It will probably change after I get the optics in. I am thinking about splitting the part in half with the focuser mount on one side and the non-focuser side on the other. Have screw joint to put them together. Unsure for now.

 

jscottb

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Re: My scope focuser upgrade
« Reply #5 on: October 22, 2017, 03:13:23 PM »
Well have made a few changes. I decided to make the focuser a Crayford/Rack&Pinon hybrid.

2017-10-22 14.47.42.jpg
*2017-10-22 14.47.42.jpg (722.03 kB . 577x630 - viewed 22 times)
2017-10-22 14.46.26.jpg
*2017-10-22 14.46.26.jpg (553.96 kB . 438x613 - viewed 21 times)

Will sand and put together soon.

I have the front and rear of the scope done now and will print soon. Working one a truss adjustment mechanism so I can change the focal length on the fly.
 

 

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