Old School - How to layout a cone

Here are the basics for laying out a cone when you don't have access to the wonderful online tools that have been presented elsewhere on the forum (or don't have access to a printer capable of handling the output thereof!) You'll need a compass and a ruler (or, if you have drafting tools, a straight edge and a scale):

Draw a centering line and mark the length of the transition. (No, you don't have to use the ISO centerline format)


Draw a line to represent the diameter of each tube, centered on your centerline. (I use 4" Blue Tube and 38mm LOC mmt here)


Connect the endpoints...


...and find their intersection


Draw a circles from the intersection point to the endpoint of each tube


Cut at least 180° (if the overall transition angle is more than 60°, you'll want more), roll it up, fit on your tubes and mark. Cut at the mark and use the scrap as your tab to glue the edges together.

Here's an example


If you want to break out the calculators, you can multiply the SIN of the angle from line to centerline (in the 3rd figure, it's 16.56°) by 360 to get the actual cutlines for the cone (102.6° in this example)

Good Post. Should be a Sticky in the Techniques Section.
That's helpful stuff to know. Thanks for that.

Thanx!

Heres how we "Old School" Draftsmen Lay out any size Cone or transtition for the sheet metal mechanics.
Step by Step, bottom to top of sheet. All thats needed is a rule, compass and pair of dividers.

Wow this is super cool! Thanks for sharing