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Old 05-14-2023, 10:04 AM
Abdullahsamir Abdullahsamir is offline
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Cool I finaly found a truncated cone plugin for inkscape!!!

GitHub - quirxi/SheetMetalCone: This is an inkscape extension to unfold a frustum (=truncated cone) or a cone (if cut diameter=0) and generate a sheet cutting layout or flat pattern projection that can be rolled or bend up into a (truncated) cone shape.

For making a mig-15, mig-21, or any other round tapering shape!!!
Thank me later!!!
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Old 05-14-2023, 03:48 PM
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MacSongLi MacSongLi is offline
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Thank you for posting this. I didn't even know that this add on was available.

Have you tried it yet?

Gary
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Old 05-14-2023, 07:36 PM
Abdullahsamir Abdullahsamir is offline
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Your welcome!!!
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Old 05-14-2023, 07:36 PM
Abdullahsamir Abdullahsamir is offline
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and yes, I have tried it it has great UI and is blazing fast on my 2018 laptop!!!
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Old 05-15-2023, 04:04 AM
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Quote:
Originally Posted by Abdullahsamir View Post
and yes, I have tried it it has great UI and is blazing fast on my 2018 laptop!!!
Excellent. I'm going to give it a try. Once again, thank you for the post.

Gary
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Old 05-15-2023, 09:07 AM
Siwi Siwi is offline
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Great news. Will it create parts where the segment is a different gradiant (side 's' on the diagram) on opposite sides or would the designer need to generate two half-frustums and combine them? I've been thinking recently about how to adapt Bruno's basic method to work in Inkscape. One of the major advantages of this would be that the same program would be used for both the design and the painting.
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Old 05-15-2023, 11:08 AM
Laurence Finston Laurence Finston is offline
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I'm not trying to criticize this package in any way and maybe I'm missing something, but there is no particular difficulty in finding the development of a cone. To find the development of a truncated cone, all you have to do is find the developments of two cones. I've attached a couple of figures in PNG format to show what I mean. The file "cone.mp.txt" contains the source code for the "throwaway" program I wrote for these figures in MetaPost. I added the ".txt" extension so I could upload it. Assuming the name is changed back to "cone.mp" (which only affects the names of the PNG files) this would be how to run it:

mpost -numbersystem="double" cone.mp

MetaPost can generate SVG and that's what I wanted to do, because to the best of my knowledge, that's what cutting plotters use. However, the forum software doesn't allow you upload SVGs, so I had MetaPost generate PNG instead.

The triangle p0p1p2 is the projection of the cone onto the two-dimensional plane. I've divided the development into 12 panels. I could have used 6 or 24 or 1000 or any other number within reason. The distance from any point on the circumference to the fulcrum will be the same, i.e., the magnitude of p0 - p2 == the magnitude of p1 - p2.

All I had to do was rotate p0 around p2 by multiples of 360/12 to find the points p9, p10, p11 ... and p3, p4, p5 ... The circumference can easily be calculated and divided by 12 but there was no need, because MetaPost automatically generated a smooth curve through the points. The curved parts of the red and blue paths are just circles with radii equal to the distance m0 = the magnitude p0 - p2 and m1 = the magnitude of p15 - p2, respectively.

I hope someone will correct me if I'm wrong, but I've looked at these figures and can't see any mistake.

Edit: The thumbnails didn't look too good so I put both images into a PDF and uploaded it.
Attached Thumbnails
I finaly found a truncated cone plugin for inkscape!!!-cone_1_001.jpg   I finaly found a truncated cone plugin for inkscape!!!-cone_1_002.jpg  
Attached Files
File Type: txt cone.mp.txt (3.2 KB, 6 views)
File Type: pdf cone.pdf (6.7 KB, 6 views)
File Type: txt cone.txt (712 Bytes, 4 views)

Last edited by Laurence Finston; 05-15-2023 at 11:20 AM.
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Old 05-15-2023, 12:24 PM
Siwi Siwi is offline
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I just had a play around with a simple cone and it's possible to do this in Inkscape with a few calculations. But could someone check this process to see if I've made any stupid brain farts?



You need some obvious measurements: D, the diameter of the base of the cone; d, the diameter of the top of the truncated cone, and S, the length of the side of the cone (we're assuming here that we are calculating for a regular truncated cone)


Find the circumference of the values D and d with maths that most 12-year-olds should know, pi x diameter. We will call these values Dc and dc

Then draw a complete circle whose radius is 2xS, we will call this C.

You then need to calculate how much to reduce the circumference by to get the correct length that matches the value of Dc and dc. Unfortunately I cannot find a way for Inkscape to show the length in mm of a circumference, but it will allow input in degrees, so we need to convert. Calculate the circumference of the circle C, then divide by 360. Then divide the value Dc by this number to find the degrees the development will have, and input this to generate the correct slice. This should then be done again for the value dc to find the truncation at the top, and by the use of the Difference or Cut Path tools a single 'model piece' can be created.
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Old 05-15-2023, 01:02 PM
Laurence Finston Laurence Finston is offline
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Quote:
Originally Posted by Siwi View Post
Then divide the value Dc by this number to find the degrees the development will have, and input this to generate the correct slice. This should then be done again for the value dc to find the truncation at the top, and by the use of the Difference or Cut Path tools a single 'model piece' can be created.
I don't think you need to calculate the number of degrees of the development. I think it's always possible to use 180 (the angle at p2 in my example), because using a different angle is equivalent to to using 180% with a different cone. For example, if you cut off one of the twelve sections in my example and join the remaining 11 at the edges, you still get a cone with the same length from the points on the circumference on the base to the fulcrum but with a steeper angle. You can continue removing sections until you only have three. This is equivalent to using 12 (or any other number of) sections for the corresponding new cones.

The same applies to any other angle within reason. You could use 120 or 150, for example.
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Old 05-15-2023, 06:37 PM
Abdullahsamir Abdullahsamir is offline
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Quote:
Originally Posted by Siwi View Post
Great news. Will it create parts where the segment is a different gradiant (side 's' on the diagram) on opposite sides or would the designer need to generate two half-frustums and combine them? I've been thinking recently about how to adapt Bruno's basic method to work in Inkscape. One of the major advantages of this would be that the same program would be used for both the design and the painting.
Yeah, I think so I haven't gotten to play with it THAT much so I don't know ALL the ins and outs, I just wanted to share it in case ppl haven't heard of it before.

I see what you are saying though.
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