I use flanges as much as possible. It makes things a lot simpler later
when you remodel, rework or swap parts. I always use the same template
so they always match. This template is generated with a drawing program
so it is perectly accurate.
I use 1.2 mm brass sheet. You could go up to 1.5mm without too much difficulty. I reckon any more and it would get too hard for the tools I use.
My flanges are always 75mm square.
Here's how I do it......
The tools I use.
Template cut out
Template stuck down with glue stick.
Brass sheet cut to size.
Careful centre punching. Punch the centre as well.
Use a compass and centre to scribe the tubes diameter so you can file to the mark.
Slow and careful drilling (4mm). Spray some oil on it to make it easier.
Nip out the centre Ninja star.
I use my aviation snips to take off the shape points.
File to the scribed mark. It won't take as long as you think if you use a vise and a good file.
Drill the screw holes (6mm). I make these holes oversize for the screws I use so that if you're slightly out it won't matter.
Flanges at work.
If you want to see how I make my gaskets GO HERE