Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> ATM, Optics and DIY Forum

Pages: 1 | 2 | 3 | 4 | 5 | 6 | (show all)
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: nevy]
      #5774274 - 04/02/13 10:02 PM

Marc Cowen 45.7LBS
kfrederick 51.0LBS
ausastronomer 47.4LBS
Tezster 48.5
Nevy 51.25

I am going to need a very accurate scale when this is done.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dave O
sage
*****

Reged: 12/21/11

Loc: Sri Lanka
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5775133 - 04/03/13 10:09 AM

I'll give you the benefit of doubt ... 39.9 lbs.

Post Extras: Print Post   Remind Me!   Notify Moderator  
VectorRoll
super member


Reged: 11/27/12

Re: The Making of my 20" telescope for a Carl Z mirror new [Re: nevy]
      #5775574 - 04/03/13 01:28 PM

Nice design. I really like the idea of Carbon Fiber Balsa Wood. I'll have to remember about that for some projects that I may do in the future.

I can't wait to see what it turns out like when you are finish.

On your contest.
I was going over your design to try and figure out the weight. I see you are hoping it would be under Forty Pounds. i think you can do it. If I had to guess, I would estimate it to be about 38.5 pounds. So that is my guess for your contest.

38.5 lb



Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: VectorRoll]
      #5777292 - 04/04/13 10:16 AM

ok so need some more feedback? SIPS Paracorr which is better and with F4.5 is it going to make a noted change in the view? Spend 90% of time with 26mm to 3mm but who knows with this new mirror. Also I have moved the center of the secondary mirror 4" from the bottom of the cage, my thinking is I will get much less light behind the secondary but is this to low. My cage is 15" top to bottom and I do not want to add extenshions to block light but am happy to put a black wrap around the struts. Let me know what you think.

Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5780350 - 04/05/13 07:04 PM

working on the balance problem trying to find out the right COG, any help with the difference between the paracore and the sips system would be great thanks.

Post Extras: Print Post   Remind Me!   Notify Moderator  
TxStars
Pooh-Bah
*****

Reged: 10/01/05

Loc: Lost In Space
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5781011 - 04/06/13 01:28 AM

How about 46.7lbs

Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: TxStars]
      #5781141 - 04/06/13 04:29 AM

Hay Marc Cowen is this how you wired your spider, I just have it mounted temperly not center or anything but it feels solid.



Hiden hardware


Going to do some sanding to clean the mount up more and might paint the ss bolts black.




going to replace lock nut with banjo tenshiner, will look better and be much easer to set tenshion in wires with little added weight.


weight of secondary is 5lbs + focuser at .8lbs + secondary mirror at 1Lbs and ? 2lbs for sipps. total for secondary with sipps would be 8.8 lbs or 6.8 with out sips.
Anyway more updates latter.



Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5781143 - 04/06/13 04:31 AM

Marc Cowen 45.7LBS
kfrederick 51.0LBS
ausastronomer 47.4LBS
Tezster 48.5
Nevy 51.25
Gatorengineer 70

Dave O 39.9
Vector Roll 38.5
TxStars 46.7
Nightstarker 44

Edited by ctcables (04/06/13 06:21 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
nightstalker
sage


Reged: 03/30/07

Loc: Great South Land
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5781170 - 04/06/13 05:58 AM

44 pounds with a tak 6x30

Edited by nightstalker (04/06/13 06:02 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
gatorengineer
Carpal Tunnel
*****

Reged: 02/28/05

Loc: Hellertown, PA
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: nightstalker]
      #5782159 - 04/06/13 04:38 PM

you forget my 70 lbs... Which would still be amazing for a 20"...

The lightest usable large aperature scope I know of is here from a master builder who frequents this site at 63 lbs for an 18"..... one of the prettiest scopes I have ever seen as well...

http://www.stardazed.com/MoonsilverIV.html

Not trying to be a troll, just a realist....


Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: gatorengineer]
      #5782359 - 04/06/13 06:26 PM

Gator that indeed is one very nice looking telescope I am counting on the lightness of my mirror to make up for the extra weight anof my components. 40lbs is going to be very hard and that is not including the base.

Post Extras: Print Post   Remind Me!   Notify Moderator  
mark cowan
Vendor (Veritas Optics)
*****

Reged: 06/03/05

Loc: salem, OR
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5782887 - 04/06/13 11:26 PM

Chris,

That looks OK to me. Just be careful not to crimp the wires with the through-holes on the secondary holder, you might want to radius those corners and only tighten it up once on any given set of strings - another reason to follow the design and use the flex plate and collimation screws for tweaks rather than messing with wire tension. I recommend using a jig to fix the secondary assembly in space before tightening down the wires (I updated my web site to say this a while ago) and also note the tension is not high at all - the spider gets its stability from the geometry, not from tension.

.008" might be on the light side for a 3.5" secondary but of course you can always change it as needed.

Best,
Mark


Post Extras: Print Post   Remind Me!   Notify Moderator  
gatorengineer
Carpal Tunnel
*****

Reged: 02/28/05

Loc: Hellertown, PA
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5784538 - 04/07/13 07:00 PM

Chris, You have a great project going... The mirror will cool superbly no question, and optically your rig will be amongst the best 20"ers in existance. No question.

Quartz mirrors actually increase the need for counterbalance. I have well over 40's of lead shot in the tail of my obsession (with its massive rocker rocker box) 2" plus thick mirror, steel mirror cell, etc). Its all about the balance, and moment arms a 31 nagler is a bugger to balance.....

Great project and cant wait to see the end product.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: gatorengineer]
      #5784879 - 04/07/13 10:00 PM

Yep COG is a bugger for sure gator; because of my very large bearing (effective 36" R) my COG is out there around 18 inches from face of mirror. Also I am working on making the bearing into what some might call a 2 strut system but the cage of the mirror replaces the lower struts and the bearings form the mid box making my top struts around 40". May not be a small system but because most of it is hollow it is much stronger and lighter. Will post some new photos along with my less than 1lbs upper strut.

This strut folds into a triangle that is 2.5" OD by 47" long and is less than one pound. Will cut down to size when complete, this is also going to get covered in carbon fiber.



Revised plans.


Looks like the added sips and extra epoxy to make it look nice is going to push me over the 40lb mark and then some, High hopes for supper light are not gone just revised in that I do want it to look nice as well. Anyway if you want to change your guess on the weight you can. After this I will not be posting any more updates on the weight so from this point everyone has = information. I think with the info I have posted we should get very close to a finished tube weight.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5797523 - 04/13/13 09:40 PM

Well made some head way on the alt bearings, need to work on the carbon fiber lay up next.





Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5801867 - 04/16/13 01:20 AM

Got started on the carbon fiber lay up. Lots of work left to do but it is going well.



Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5814431 - 04/21/13 11:50 PM

Another week and a big part almost complete, this took lots and lots of time and checking but it looks to be turning out very well. So here are the photos.


This is how it will sit, cross bracing not showing in this photo as I still need to make them which is next.

inside of alt bearings showing the 4 cross bracing supports.




Post Extras: Print Post   Remind Me!   Notify Moderator  
mark cowan
Vendor (Veritas Optics)
*****

Reged: 06/03/05

Loc: salem, OR
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5815479 - 04/22/13 02:52 PM

Looking great Chris!

Best,
Mark


Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: mark cowan]
      #5816770 - 04/23/13 02:34 AM

Thanks Mark, Getting things ready for it. Just put an order in for a ES 20mm 100 and found a great deal on an Ethos 13mm. Not sure if I should sell the 10mm and 4mm radian because I am not sure how they will work out with the SIPS system. Anyway going to make the COG bottom heavy. I have lots of room with the alt bearing location to shift the weight up top or to the bottom. I am thinking it is better to be bottom heavy so when the big eyepiece goes in it is just right.

Post Extras: Print Post   Remind Me!   Notify Moderator  
ctcables
professor emeritus


Reged: 11/14/06

Loc: Oregon
Re: The Making of my 20" telescope for a Carl Z mirror new [Re: ctcables]
      #5833761 - 05/01/13 07:29 AM

getting things done but it seems like it is taking way longer than I expected. The bearings were not easy but they are turning out well.





Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | (show all)


Extra information
5 registered and 22 anonymous users are browsing this forum.

Moderator:  ausastronomer, richard7, Starman81 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 7589

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics