HELP!!!! Rectangle to circle

[kriso]

Hi there all you skilled folks

I have been trying to make a rectangle to square formwork so that I can build my transition from chimney to flue. I have an opening 155mm x 330mm and need to go to a 200mm circle flue. I was planing on pouring refractory cement to make this as was not keen on this type of cutting brick work. I have been online to get a free converter / pattern but no one that I could find has it. I think CAD does it for sheet metal but don't have that.

Can anyone help in this area?

Cheers

Kris

[david s]

It would be easier to just form it in sand, right where you want it. Cast over the sand mould, then remove the sand when the casting has set. This way you won't need any fancy plans.

[kriso]

Thanks for that David, back to the basic's. Back to when I helped Dad build a mud oven in the 80's. So simple and effective.