ConeT200> first created 29/07/07 - last modified 18/01/12 Page Author: Ty Harness
Version ConeT2.00 is available to download from the members area.

Version 2 now has the flat shading options that STOR2 first introduced.

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Figure 1a,b - Flat Shading with the show normals

Also the normals can be flipped so that they point internally or externally which was a request by a registered member.

Flat Shading Print example

Please keep reading below for the existing feature set.
Version CONET132 features:

There are several improvements to the Cone Transformer (ConeT) software.

Version 132 fixes a few bugs and includes a y axis off set for oblique cones. If you are designing oval to oval transformers derived from oblique cones and there's an offset in one axis then 2 of the oblique cones require an offset in 2 orthogonal axes.

Circle to Oval Transformer
You could have made this one with the earlier version as it does not require to 2 orthogonal offsets.

Circle to offset Oval Transformer
When you introduce an offset the 2 orhtoganal offsets OX and OY within ConeT make the job vastly easier to extract dims from your plan and elevation.

Oval to Oval Transformer{I'll write more on this later}

Oval to offset Oval Transformer{I'll write more on this later}

Oval to offset inclined Oval Transformer{I'll write more on this later}

If you need to draw ovals then please download the Tygraphs software:

TyGraphs 2.x

Previous updates:

Version 131 incorporated a pattern dims layer and a pattern coords layer. In terms of the pattern coordinates the datum PPX,PPY can be reset. The PPA angle rotates the development starting line.

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Figure x a, b - Turn On either the Coords or Dims layer.

The text on screen is always displayed at the same height. Use the zoom (middle mouse wheel) and pan (left button down and drag) to examine the pattern. You can use Print Complex which also has a fixed text height it's a little easier to see more of dims than you can see on the screen.

testdims.pdf, testverts.pdf

The interface has been updated with the same features as STOR12 which include a 3D isometric display with (or without) face normals of a cone as shown in figure 1. In reality a cone would only have the one face and one normal but the triangulating method of sheet metal work truncates a surface into n faces and a normal is found for every face.

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Figure 1 - Isometric display showing the face normals

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Figure 2 - Angle between Normal Vectors for a Right Cone.

The face normals for a right circular cone are straight forward enough as the surface curvature is constant (i.e. the angle between the normal vectors does not vary as shown by figure 2) and hence it's fairly straight forward to roll a right cone.

The normals of an oblique cone (see figure 3) show just how hard it is to 'knock-up' an oblique cone in sheet metal with a rolling process. Sometimes it's possible to split the cone into sectors and roll or press the sectors. For thin sheet it is relatively easy to form the change in curvature by hand but for thick plate you are going to struggle but knowing how the curvature (angles between the faces) changes will help you press out more accurate oblique cones.

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Figure 3 - Normal vectors of and oblique cone (yellow indicates a -ve z component)

More on Face Normals

Also a key feature of the 1.2 interface is the ability to put the weld line at any position which greatly aids the manufacture of the cone either for making a 1/2 or 1/4 pattern. From figure 4 you can see I started the triangulation (or put the weld line) at position 24 out of 48 faces.

The most requested feature by users of ConeT is for oblique cuts of a right circular cone. One reason I did not include oblique cuts in the first version was I did not want users to be confused between oblique cuts of a right cone and an oblique cone. If you apply an offset to the apex or the top opening then the oblique angles will be set to zero because only parallel cuts (with the exception of a subcontrary cut) will produce a true oblique cone with a circular entry and exit.

Version 1.2 allows you to specify a top angle and a base angle for right cones where east is zero degrees looking at the front elevation (XZ plane). Oblique slicing in this form I feel is the most useful for the sheet metal worker but you could slice at any plane and each slice could be on different planes. Mathematically it would be easy to make the application slice anywhere but from a user interface and user understanding the orientation of the plane would be difficult. Figure 4 shows a right cone with 2 oblique cuts- remember the entry and exit are not circular but elliptical so you'll need to mitre any joining pipes.

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Figure 4 - Oblique cuts of a right cone

Right Cone Oblique Cuts

Oblique cuts come into their own when you need to make conical ventilators or offset swan neck funnels or tapered bends.

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Figure 5 - Swan Neck and Conical to cylindrical elbow

To feed in the parameters needed to create oblique cuts take a look at two following PDFs which by common central sphere will help you deduce the mitre angles.

Conical to Cylindrical Elbow
Offset Swan Neck

Oblique cuts of a right cone can form a tapered segmental bend as shown in figure 6.

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Figure 6a - Tapered segmental bend from a right cone.
Figure 6b - Tapered segmental bend by common central spheres.

Take a look at the following PDFs to work out the parameters needed to for CONET to produce a tapered lobster back bend.

Tapered Bend from a Right Cone 90 deg 1 full a 2 half segments
Tapered Bend from a Right Cone 90 deg 5 full a 2 half segments
Tapered Bend from common central spheres

Version 13 features

  • Oblique cuts for oblique cones; please see below.
  • Multiple page printing. Click here for more information
    Oblique Cone Oblique Cuts

    Cutting an oblique cone at any angle other than parallel to the base or the subcontrary angle will not produce a circular entry or exit. This is of very limited use to the sheet metal worker other than a complicated mitring problem. One application that utilizes the mitring aspects of an oblique cone is the tapered lobster back bend from an oblique cone. Much more information on producing a tapered lobster back from an oblique cone can be found in 'The Geometry of Sheet Metal' by Dickason [1]. CONETv12 does not allow the user to use oblique cuts. CONET v13 will allow you to override the slice angles.

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    Figure 7 a,b - Slicing an Oblique cone obliquely. The first 2 segments of a 6 segment 90 degree tapered bend.

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    Figure 8 - Using the 3D DXF export from CONET13 to make each of the 6 segments

    Take a look at the following PDF to work out the parameters needed to enter into CONET13 to produce a tapered lobster back bend from an oblique cone. The major benefit of making tapered bends from an oblique cone is the pattern nesting i.e. it's the same pattern as the frustum oblique cone. [write some more on this]

    Tapered Bend from a Oblique Cone 90 deg 6 segments

    There's more information on tapered lobster back bends on the following web page: taperedbend.htm

    [1] Dickason A,., The Geometry of Sheet Metal Work, Longman Scientific & Technical(1987, pxx)

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