LewisM
06-02-2018, 12:05 PM
I find it amusing when I see so many people ditching the Tak clamshell in favour of hinging rings, and since Tak uses some odd OTA sizes, this can be difficult, with many reverting to Parallax, K-Astec (myself included), Prima Luce or the old SoCal if you can find them.
I have added accessory plates to clamshells before, but there is always the issue of orthogonality, unless you drill an additional inline with the long axis hole in the clamshell. Most Tak owners don't like modifying anything OEM :)
So, finding the price of rings ridiculous ($200 UP), even the lower end Parallax ones, I drew up some specs for an accessory plate system to use the original clamshell without any modification whatsoever. Below is what I ended up creating.
The "cradle" end plates make sure the plate won't rotate on the clamshell "nub" - I will add Tak green felt to the radii of these after finishing the painting. I drilled the plate itself to accept 3 x 1/4 UNC's (the middle one secures the plate to the clamshell via the original hole), and 3 rows of M5 screws so I can fit Baader Vixen-style finder bases (I currently use 2 securing my guidescope, which has a Vixen-style finder-dovetail rail with small rings on top).
Of course, this idea is up-scale-able to other clamshell sizes - this one fits the Baby Q/Sky 90 clamshell (outer diameter of the clamshell being 111mm). Easy to do it for the 114mm OTA's and 125mm OTA's too, or down if you really wanted to.
Total cost of materials and labour for my mate to mill the aluminium was $100, which is quite a lot cheaper than ANY rings available for the Tak sizes (to which you then need to add another accessory plate anyway). I am sure if you have the machinery and materials it'd be essentially free.
I have since made a flush cap bolt for the securing screw rather than the exposed phillips head 1/4 UNC, and polished the stainless end plate securing cap bolts :)
I have added accessory plates to clamshells before, but there is always the issue of orthogonality, unless you drill an additional inline with the long axis hole in the clamshell. Most Tak owners don't like modifying anything OEM :)
So, finding the price of rings ridiculous ($200 UP), even the lower end Parallax ones, I drew up some specs for an accessory plate system to use the original clamshell without any modification whatsoever. Below is what I ended up creating.
The "cradle" end plates make sure the plate won't rotate on the clamshell "nub" - I will add Tak green felt to the radii of these after finishing the painting. I drilled the plate itself to accept 3 x 1/4 UNC's (the middle one secures the plate to the clamshell via the original hole), and 3 rows of M5 screws so I can fit Baader Vixen-style finder bases (I currently use 2 securing my guidescope, which has a Vixen-style finder-dovetail rail with small rings on top).
Of course, this idea is up-scale-able to other clamshell sizes - this one fits the Baby Q/Sky 90 clamshell (outer diameter of the clamshell being 111mm). Easy to do it for the 114mm OTA's and 125mm OTA's too, or down if you really wanted to.
Total cost of materials and labour for my mate to mill the aluminium was $100, which is quite a lot cheaper than ANY rings available for the Tak sizes (to which you then need to add another accessory plate anyway). I am sure if you have the machinery and materials it'd be essentially free.
I have since made a flush cap bolt for the securing screw rather than the exposed phillips head 1/4 UNC, and polished the stainless end plate securing cap bolts :)