[Ian Robinson]

Been sourcing materials to produce a DIYS carbon fibre tube for V3 of my 10" astrograph.

0.8mm x 1.2m x 2.4m Al sheet from Capral (Cardiff) is $69 and to get a 1.5m long x 0.306m OD tube rolled from an offcut from the sheet will cost $60 (labour only) by Harveys Sheetmetal (Carrington).

Harveys estimator reckons the tube will hold the shape OK once rolled , but I'll probably get a couple of spot welds to make sure.

Set me to thinking , since it's going to cost me the better part of $400 to make my carbon fibre tube , I may settle for an aluminium tube for V3 of my 10" OTA.

Wwill give a tube 1.27m x 0.31m OD of 0.9kg.
I'm pretty sure with a few reinforcing disks it'll do for mandrel , but as a stand alone unreinforced OTA tube , I'm not so sure.

Aiming at an OD of 308mm to fit my spider and cell.
2mm thick sheet will make a tube of 2.1kg.
3mm thick sheet will make a tube of 3.2kg.
4mm thick sheet will make a tube of 4.3kg.

All of these are considerably lighter than my V2 tube , the PVC tube weighs 11kg.

Must be some aluminium tubed OTAs out there ( as 10" or 12" or 12.5" newtonians ).

What's the wall thickness of the tube ?

How does it perform as far as stiffness and strength is concerned ?

Is 0.8mm thick aluminium too thin ?