Taking on a long term project such as this does have a couple of "gotchas", some small but often some are quite large.
Stuff made at the beginning may not be acceptable near the end as skill levels and knowledge accumulate, either that or I'm just too damn fussy.
The tertiary mirror holders and focusers that were made from plastic plumbing parts that I was so proud of are just not good enough.
If I was only using them individually I believe I could have got away with them but as a pair no way.
There are too many "freedom of movement" parts for adjustments that will cause too many problems later on.
SO, another design change.
I will use a couple of standard commercial (cheap) 90' diagonals something like these
Ideal for both Astronomical and Terrestrial Use Mirror Diagonal Fully Coated Optics 5 Years SkyWatcher Warranty
www.ozscopes.com.au
and cast a totally new fitting from aluminium for them.
75mm dia cone tapering to the 1.25" diagonal.
I'm awaiting a reply to check if the two tubes can be unscrewed from the triangular base as I want to replace the eyepiece tube with one a lot longer threaded at the top for another tube to thread over it giving a helical focuser for the eyepiece.
I'm in a hurry for this so no pattern, I've just loaded up two tin cans with aluminium ingots and will heat them just enough to puddle then set in the cans.
I expect they will tear in the centre as they cool and shrink but as that will be machined out I hope to get away with it. I will find out by the end of today.
If this works then I will change out the cheap diagonals for superior ones once everything works optically to my satisfaction.
I better get the furnace fired up now.