Making tee joints in pipe

Originally Posted by Blackjack

I was dredging my memory trying to remember how you developed a conic section a while back.

Very similar but I'm sure I'll be awake trying to recall it ..seem to think that the opened cylinder of the cone has to have the top & bottom reference lines and that you span off from two circles ... Now seeing as Paul is good with CAD perhaps we can con him into shoving up a piccy for us mental geriatrics to drool over

Originally Posted by pidgeon chit welder

Very similar but I'm sure I'll be awake trying to recall it ..seem to think that the opened cylinder of the cone has to have the top & bottom reference lines and that you span off from two circles ... Now seeing as Paul is good with CAD perhaps we can con him into shoving up a piccy for us mental geriatrics to drool over

Don't lay awake its bad for you!

Draw out the cone, extend the sides untill they intersect to find point "D"
Strike an arc AG with the rad the length of DA.
Strike arc A to F using E as centre
divide arc AF into 6, (More divisions = more accuracy)
use dividers to find AB
Strike AB 12 times round Arc to find point G
join G to D to complete frustum of cone
If its a truncated cone strike arc using length DC

This is a workshop method,and needs nothing more than a rule and dividers or compasses, the dimension of AB is a chord length and not a section of the true circumference of the base, the more divisions you use the more accurate the development, I usually use maths to calculate the angle.

As an aside, a BA is an art degree, my wallet is still recovering from my eldest son achieving a 1st class, BA (Hons), in graphic communication,

Originally Posted by TIG Paul

I usually use maths to calculate the angle.

That's what I ended up doing. Used some maths.