25 years ago I made a roller blind for our conservatory roof 14ftX9ft. It has worked well with the odd repair but it has now gone for a burton on one side.
A friend has suggested that I make a new axle of aluminium tube and I find that it is readily available in 4" or 4 1/2" diameter in the correct length in 10 or 16 swg.
My question is - will it be rigid enough and can I use the thinner material to reduce weight and cost ?
As Noldi says, the strength is in the tubular shape, so there wouldn't be a problem with deflection, provided the weight of material isn't that great. The problems with tubes of this size tend to come at the end bearings, so make sure you get that part right.