Yeah it was mine...lol But that was to produce a 90 degree elbow. I borrowed a large bandsaw for that task in the end and god was it so much easier than a grinder and disc.Once you make a template to mark the material from it won't take long to make. Was there not a thread about this a wile back that had a link to a program that created a printable profile for cones?
Possibly if I had a fly press.. ...I sold mine as it took up too much space in my unit, let alone when I was forced to downsize to my garage.It may be 2015 but there's no need to be so modern, I'll stick with Radial line development thank you
To make the part in the first post, could you make a former for a fly press and flare it out from a piece of thin tubing, the same diameter as the smaller half.
Well the gauge I am using is way OTT but I am trying a theory on quality over quantity. I think the wall of the pipe is approx 4mm and the OD is 75mm. heavy duty for a flue pipe. BUT a number of people are asking for it to fit commercial flue pipe dual wall/thin wall etc etc. So I was looking at creating my own reducer.What gage the flare?
And what size the pipe?
You might get away with a forming tool which is pressed in a vice?
<edit> Oh, noticed you said 3 to 4 inch! probably not in a vice then...
If you had a lathe you could make a mandrel the shape you want to fit the large id of the pipe, place the pipe in the chuck with the mandrel inside, fabricate a rounded outer dia bearing ( like a self aligning plumber block) to be held by the inner race, in the tool post, warm the pipe and reduce it down by pushing the bearing against pipe whilst spinning it, it will stretch the pipe out longitudinally whilst reducing the diameter down to the dia and shape of the mandrel.
A mate uses this method for forming the end of 3-4" ish long stainless top cups for springs, for morgan 3wheelers out of straight stainless pipe, he forms it down through 90* and is left with a small hole in the base of the cup, that is drilled out to suit the king pin.
the spring then fits inside the cup, when polished you could not tell they are formed out of straight pipe it takes seconds to form and a couple of minutes to polish to mirror finish he make one to slide inside the other with clearance then the springs cannot be seen.
It is called metal or pipe spinning forming i think
NOW...to try and understand your message.