The Making of my 20" telescope for a Carl Z mirror
Posted 06 April 2013 - 05:26 PM
Posted 06 April 2013 - 10:26 PM
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.
Posted 07 April 2013 - 06:00 PM
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.
Posted 07 April 2013 - 09:00 PM
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.
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.
Posted 13 April 2013 - 08:40 PM
Posted 16 April 2013 - 12:20 AM
Posted 21 April 2013 - 10:50 PM
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.
Posted 23 April 2013 - 01:34 AM
Posted 01 May 2013 - 06:29 AM
Posted 01 May 2013 - 02:01 PM
Posted 01 May 2013 - 09:06 PM
Posted 03 May 2013 - 03:15 PM
Posted 03 May 2013 - 04:17 PM
Posted 21 May 2013 - 10:21 PM
Posted 25 May 2013 - 08:52 PM
Posted 28 May 2013 - 04:05 AM
Posted 29 May 2013 - 08:00 AM
Posted 29 May 2013 - 10:34 AM
Posted 29 May 2013 - 02:42 PM
Ok let’s do something more simple, dose the SIPS change the focus point? Will I need to add or minus distance from secondary by adding the SIPS? Or am I correct in assuming the SIPS just moves it out so everything will come to focus as if the SIPS was not installed. Never had a paricor before or SIPS so I just do not know. Hope fethertouch sends info on this part if I get no answers here.
Yes, it changes it. Study that photo, it explains the geometry, it shows the original focal plane and the new one as well.
In any case I wouldn't cut those struts shorter until you've installed the mirror and confirmed the focal plane of the entire OTA. You know, just to be sure.
Posted 29 May 2013 - 09:01 PM
Posted 09 June 2013 - 08:49 PM
Posted 18 June 2013 - 06:46 AM
Posted 19 June 2013 - 08:36 PM