[Ian Robinson]

I've finished my Astrograph , used an offcut of 300mm NB UPVC stormwater pipe (price was right-ie free).

The resulting OTA (10" f4.66) in astrograph configuration = OAG + SSAG + 40D comes in at 21.5kg , of which 11.6kg is the tube .

I've done my RA torque balance calcs and these indicate I need another 10.5kg (=7kg + 3.5kg) of counterweights + a small adjustment weight about 13oz to move about for perfect balance about the RA pivot point.

I'd rather make the OTA loose some weight , ie scrap the UPVC and get a CCF tube to reduce the load on the gem.

My calcs indicate I can reduce my OTA mass by 6kg if I change to a CCF tube same external size and only 3mm thick , which will mean I only need an extra 7kg counterweight.

Those who did their own CCF tubes for newtonians or other fat OTAs ,

1) what were your final tube specs (OD, wall thickness, length, weight (tube alone)) ?
2) how much did it cost ?
3) where did you source the materials if you made it yourself ?
or
4) where did you buy the ready to use tube ?

Tbanks in advance.
3)