Accurate method to wrap a sketch to a cylinder

[PEC]

Hi,
I think this has not been posted before, here is an accurate method to wrap a sketch onto a cylinder.

Orthogonal projection of a plane onto a cylinder creates distorsion. One solution is obviously to slice the cylinder to reduce error. The following table gives an estimation of the maximum error of the projection for a given number of slices.

2 slices means projection of a plane on half the cylinder, which leads to infinite distorsion at the limit of the projection.
With 16 slices, worse case error is less than 2%, which is not noticeable.
With 64 slices, worse case error is about 0.1%.

The idea is to create a flatten version of the cylinder, project the sketch on the flatten version, extrude it if needed, and then wrap the cylinder to create the final shape in a systematic way, using mirror and align tools.
It’s a five minutes process for 16 slices, as in the video, but it just requires 1 additional minute to go to 32 slices and do not require any computation at all.

There is only one limitation: ensure there are no spline control point too close (less than 0.01mm) to any slice’s edge or extrude may fail.

This method can be extended to project a sketch onto a cone
Accurate method to wrap a sketch around a cone

[TigerMike]

Excellent demonstration. Bravo!

[Hammerhand]

Super helpful right now. Thank you.

[welshsteve]

Great work ‘around’ (pun intended) and exactly the way that I’ve been doing it both here in Shapr3d and in SketchUp.

[PEC]

Hi Macher, welcome to this forum.

@Macher

My boss would now say:
A typical example of how to replace a standard CAD function with as much effort as possible.

I think your boss should not say that as he would be mixing to separate topics.

If the question is “do we miss a wrapping or emboss function”, the answer is yes, no debate on that. The minute it will be available, we will all use it.

But at present, we don’t have wrap or emboss tool, leaving only two things we can do:

• ask for it : it has been requested several time so I’m 100% sure the Shapr3D’s team is aware of this;
• find the best solution to replace this CAD function with as little effort as possible for those who don’t have access to Solidworks, Fusion360, Inventor, Rhino, etc on their tablets, which was my two cents’ contribution.

So now I’m afraid that you put your boss intro troubles as he will have to prove he is the boss
Can he beat 1 minute with no visible distorsion, using only Shapr3D and a better method? Lets call it the One minute challenge !

• The first step of the method, you have to do it only once in a lifetime, as you can save the flatten shape and scale it to the desired diameter when you re-use it, as in the video;
• The second step = the sketch, you have do do it anyhow, so it is not taken into account for the time.