Frustum of a cone

[skow69]

There have been several requests recently for a way to lay out a template for a cone. Here is the old school, low tech method. All you need is a measuring stick and compass. If it is not clear, please ask.

conicalfrustum.gif (1.81 KiB) Viewed 23224 times

1) Draw the vertical origin line.
2) Draw r2 and r1.
3) Draw the diagonal to locate point F.
4) Draw the arcs extended from r2 and r1.
5) Calculate the circumference of the base c2. Divide by 20.
6) Set your compass to the distance c2/20.
7) Walk your compass 20 steps along the arc of r2. This will be the distance c2.
Draw a line from that point through F.
9) The purple area is your template.

[Kareltje]

Nice! I like the clean, simple way to make an important and difficult to handle part!

[shadylane]

Thanks for posting the info
Since I'm almost mathematically illiterate
I've been using paper, tape and scissors to make Frustum templates

[der wo]

I once used this method to make a BIAB. It worked good. The method better than the bag...

[Stinkehinke]

Love it. I learnt this in trade school and have used it many times. Circles are difficult, cones are more so. One of the best bits of maths that I know.

[grousehunter]

Thanks skow69. Very useful.

[still_stirrin]

...Circles are difficult, cones are more so...

The "cone of frustration".

[skow69]

Finally! A use for that geometry crap they made you take in high school.

[rad14701]

Nice write-up... I prefer the method Dan P. described in his Frustum/cone development for lyne arm etc. topic... Virtually no math required... That was the method I learned to make frustum patterns by years ago... Been using the method recently in preparation for making a dust separator... Software works great but if you don't have a plotter it's easier to do hand drawn layout instead of piecing standard printer paper sheets together, IMHO... Just wanted to offer up another option for those who haven't stumbled across this alternate method...

[SpiritOf76]

this website uses only imperial measurements, but it will create a template you can print and layout on your copper.

https://www.blocklayer.com/cone-patternseng.aspx

[corene1]

Easiest layout I have found is ConeCalc. Plug the large diameter , the small diameter and the height needed into the program and it will give you the layout for that cone. Just make sure you put the diameters in the proper slot. https://i-logic.com/conecalc/

[Eire Whiskey]

this website uses only imperial measurements, but it will create a template you can print and layout on your copper.

https://www.blocklayer.com/cone-patternseng.aspx

Easiest layout I have found is ConeCalc. Plug the large diameter , the small diameter and the height needed into the program and it will give you the layout for that cone. Just make sure you put the diameters in the proper slot. https://i-logic.com/conecalc/

Both these are good. The plus side of the one is it's on your computer in case the internet fails, kinda common around here. Thanks

[Bushman]

I have a program called Rhinoceros that I use it allows me to make a 3D model which I can calculate the volume. From here I can do a roll-out that will lay it out in 2D with both the top and bottom. What it doesn’t do is add the tabs. I have done several layouts for other members along with my own build. It’s not a really high end software but is a bit expensive for just our use. I was given the software from the company as I used to do training for teachers in our state. I also used it for my dephlagmater and converted to CNC code to cut the parts.

[BlueSasquatch]

I have a program called Rhinoceros that I use it allows me to make a 3D model which I can calculate the volume. From here I can do a roll-out that will lay it out in 2D with both the top and bottom. What it doesn’t do is add the tabs. I have done several layouts for other members along with my own build. It’s not a really high end software but is a bit expensive for just our use. I was given the software from the company as I used to do training for teachers in our state. I also used it for my dephlagmater and converted to CNC code to cut the parts.

I've been trying to get Autocad to lay flat a model, but its not a good software for that, seen Rhino mentioned, but also costly.

I found this website useful to do the hard work that skow69 shares. https://craig-russell.co.uk/cone-calculator/

Then some quick 2D autocad work and I've got a flat cone. For curved surfaces like a whiskey ball, or dome-top, I just find the length of the Arc, which autocad nicely tells you, and use that for the height, should account for the excess material needed, so you can "squash" the cone down, and make it bulge out (with some copper-working) and have your curved surface. Works in theory anyways.

Trying to figure out how to best flatten, a reducing swan-neck. 4" to 2" and something like a 135 degree angle.

[tjsc5f]

Trying to figure out how to best flatten, a reducing swan-neck. 4" to 2" and something like a 135 degree angle.

I use the sheet metal feature in Solidworks for stuff like this. If you can provide a sketch or pic of what you're looking for, I can draw it up for you next week.

[Chronical]

Two questions

For first question here is current situation:

So I’m gonna clean the edges up and possibly add a collar of 3-4” to braze a 6” tc flange but do I need to flare the edge some or can I just smooth out and braze directly to collar

and

same thing for lyne arm I have 2” l type copper pipe do I need to drill directly 2” and solder or drill 1 7/8” and flare the extra before putting 2” pipe with 2” tc for lyne arm