Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Sourcing a focuser for small refractor build

  • Please log in to reply
10 replies to this topic

#1 Usernamealreadytaken

Usernamealreadytaken

    Lift Off

  • -----
  • topic starter
  • Posts: 9
  • Joined: 25 Jan 2022

Posted 26 January 2022 - 03:17 PM

I'm currently trying to build a 60mm f11 achromatic refractor and I can seem to find any 1.25 inch focuser replacements/upgrades that are meant for refractors. Plenty of focusers meant for newts though. I want to stick to 1.25 inch parts to keep down weight and save money since even the most inexpensive 2 inch focuser would raise the budget of this little project about 300 percent and everything I currently have is 1.25 compatible. Right now, it seems like my best option is to just tweak my design a little to fit one of the newtonian-specific focusers I can get within budget but I'm worried it won't be as simple as I'm thinking. Can anyone here see a potential issue with that plan? Or alternatively do you have other ways of obtaining telescope parts? I'm also considering finding an old junk scope on the used market and cannibalizing the focuser, and cannbibalizing any suitable rack and pinion assembly and trying to fashion my own focuser. Has anyone here tried anything similar? Grateful for any insight, knowledge, or experience!

Also I'm a beginner but this seemed too specific for the beginner forum. Mods: please move this if it doesn't belong here.

#2 zakry3323

zakry3323

    Mercury-Atlas

  • *****
  • Posts: 2,812
  • Joined: 11 Apr 2016
  • Loc: Fairfield, Westmoreland County, PA

Posted 26 January 2022 - 03:36 PM

No you're right- focusers that fit 60mm tubes are oddly a little difficult to find. This thread talks about one all-metal model that you can get off the boat if you don't mind waiting for shipping. 


  • Usernamealreadytaken likes this

#3 plyscope

plyscope

    Surveyor 1

  • -----
  • Posts: 1,964
  • Joined: 23 Nov 2006
  • Loc: Perth, West Australia

Posted 26 January 2022 - 04:12 PM

There is this one available from TS in Europe however shipping may make it too expensive.

 

https://www.teleskop...-connector.html

 

A complete scope for a little bit more money.

 

https://www.teleskop...tical-tube.html


Edited by plyscope, 26 January 2022 - 04:15 PM.

  • Usernamealreadytaken likes this

#4 MitchAlsup

MitchAlsup

    Fly Me to the Moon

  • -----
  • Posts: 6,367
  • Joined: 31 Aug 2009

Posted 26 January 2022 - 05:01 PM

What you need is to remove a base plate from a reflector focuser, and to machine up a tube-end that fits (moderately tight) the refractor tube (with 3+ screws) and has mounting holes in its center for the focuser of choice.

 

For a 60mm refractor tube you could get away with ½" 6061 T6 plate 2½"×2½", and 20 minutes of work on the lathe. Turing a shoulder of tube ID on the edge, turning the edge to fit tube OD, and drilling then boring out a hole in the center for the focuser draw tube.

 

Then you just need to drill and tap some holes.


  • Usernamealreadytaken likes this

#5 Usernamealreadytaken

Usernamealreadytaken

    Lift Off

  • -----
  • topic starter
  • Posts: 9
  • Joined: 25 Jan 2022

Posted 26 January 2022 - 06:11 PM

No you're right- focusers that fit 60mm tubes are oddly a little difficult to find. This thread talks about one all-metal model that you can get off the boat if you don't mind waiting for shipping. 

Thank you this was the discussion I was looking for!


  • zakry3323 likes this

#6 Usernamealreadytaken

Usernamealreadytaken

    Lift Off

  • -----
  • topic starter
  • Posts: 9
  • Joined: 25 Jan 2022

Posted 26 January 2022 - 06:33 PM

There is this one available from TS in Europe however shipping may make it too expensive.

 

https://www.teleskop...-connector.html

 

A complete scope for a little bit more money.

 

https://www.teleskop...tical-tube.html

Thanks! Just can't afford the shipping to Canada but it's good to know these things exist. And I do already have a decent scope this is just a fun project for me. Fully aware I'll likely spend more than  would have on a budget scope to build something of lesser quality, but I'm having a good time.



#7 zakry3323

zakry3323

    Mercury-Atlas

  • *****
  • Posts: 2,812
  • Joined: 11 Apr 2016
  • Loc: Fairfield, Westmoreland County, PA

Posted 26 January 2022 - 06:37 PM

Thank you this was the discussion I was looking for!

Great! It's been a helpful thread for me as well :)



#8 Usernamealreadytaken

Usernamealreadytaken

    Lift Off

  • -----
  • topic starter
  • Posts: 9
  • Joined: 25 Jan 2022

Posted 26 January 2022 - 06:37 PM

What you need is to remove a base plate from a reflector focuser, and to machine up a tube-end that fits (moderately tight) the refractor tube (with 3+ screws) and has mounting holes in its center for the focuser of choice.

 

For a 60mm refractor tube you could get away with ½" 6061 T6 plate 2½"×2½", and 20 minutes of work on the lathe. Turing a shoulder of tube ID on the edge, turning the edge to fit tube OD, and drilling then boring out a hole in the center for the focuser draw tube.

 

Then you just need to drill and tap some holes.

Thanks so much! I'm gonna try to find a deal on purpose built one, but I have a feeling I'll probably end up going this route.



#9 MitchAlsup

MitchAlsup

    Fly Me to the Moon

  • -----
  • Posts: 6,367
  • Joined: 31 Aug 2009

Posted 26 January 2022 - 08:15 PM

Thanks so much! I'm gonna try to find a deal on purpose built one, but I have a feeling I'll probably end up going this route.

Also note: Baltic Birch plywood might also suit your needs, and is a bit easier to work then metal.



#10 Usernamealreadytaken

Usernamealreadytaken

    Lift Off

  • -----
  • topic starter
  • Posts: 9
  • Joined: 25 Jan 2022

Posted 27 January 2022 - 03:21 PM

Also note: Baltic Birch plywood might also suit your needs, and is a bit easier to work then metal.


Thanks! Cheaper too. Just a random question about using wood for otas: does it ever cause collimation issues when the wood contracts and expands due to temp and humidity? I assume this is beyond the accuracy requirements for my project but just curious.

#11 Mph100

Mph100

    Sputnik

  • -----
  • Posts: 36
  • Joined: 14 Jan 2021

Posted 31 January 2022 - 05:00 PM

AliExpress had cheap focusers.the ones you order off ebay all come from there anyway might as well save a few quid yourself aslong as your not in a hurry as shipping can take some time, most items I've ordered have usually turned up within three weeks


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics