How to get the extrusion taper with an offset to make a pointed shape?

[sinuzz]

Hi there,

I would like to find out how to use the extrude taper functionality with an offset to make a pointed extrusion. It seems like after using an offset, the taper angle is still against the "to" object selected.

How do I fix this while still being parametric?

[laughingcreek]

by what means are you figuring the angle needed to make it "come to a point," and still be parametric?  even if this approach worked they way your expecting it to, you would have to manually fix the angle if you where to change the wall thickness of the body.

[TheCADWhisperer]

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@sinuzz wrote:

How do I fix this while still being parametric?

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File>Export and then Attach your *.f3d file here.

[sinuzz]

I will definitely need to add some maths to find the angle which will change depending on the height of the "flat" side. 

I can definitely accomplish this by other means, but I would like to see if I can contain this operation within an extrude, and whether this is a bug that the angle doesn't take into account the offset when calculating if it's valid

Adding f3d here: 

[TheCADWhisperer]

Sketch1 doesn't have any dimensions?

Never a good sign...

I will continue examining...

Plane2 is a duplication of the XZ plane?

Extrude4 in Body2 - no clearance with Body1 - we cannot manufacture perfect parts in the real world?

Plane3 is a duplication of Plane2 and of the XZ plane.

Very very thin corner in Body2...

[sinuzz]

I am sorry but this is just me practicing with a simple model. I am pretty sure that it's imperfect. I would only like to find out how to do the pointed extrude so that I can use it in a different, more structured project. 

Thanks for your understanding. 

[TheCADWhisperer]

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@sinuzz wrote:

I am sorry but this is just me practicing ...

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If I give you step-by-step instructions - are you willing to follow my instructions?

[sinuzz]

Yes, for sure. 🙂

[TheCADWhisperer]

Start a new file.

Right click at the top node of the browser and select New Component.

Make the new component active.

Start a new sketch on the top plane and create a rectangle and dimension it.

[sinuzz]

Sure. I have it. 

[laughingcreek]

pretty sure he wants you to post your file with the one sketch so you can discuss.

[chrisplyler]

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@sinuzz wrote:

How do I fix this while still being parametric?

By putting a point where you want it to be, parametrically controlled as you desire, and then just LOFTING your rectangle to that point instead of trying to get the extrude tool to do it.

[TheCADWhisperer]

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@chrisplyler wrote:

..and then just LOFTING your rectangle to that point instead of trying to get the extrude tool to do it.

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Better take a look at the geometry...

[sinuzz]

I clarified many times now that the only thing I am looking for clarification about is why the taper angle isn't "coming to a point" with the offset set. I am a beginner wanting to learn the program for hobby 3D printing, and I understand your points about structuring the project better. 

What I am trying to understand is why is the program not behaving like I expect it to, which is to taper the extrusion into a point with an offset value. The main learning I expected out of my original question was to see if I found a bug there, or do I have a fundamental misunderstanding of how extrusion with taper angle works with an offset value. 

[chrisplyler]

Because the angle value entered has no inherent relationship with the distance of the extrusion.

You'd have to set up a parameter with a trig formula, and drive the taper angle with it. And since you're using To Object, you'd also have to have a parameter with the wall thickness to get the distance used in that formula, and since you want a non-zero offset, you'd also need a parameter to subtract from the wall thickness so you have the actual distance for the formula.

You use those parameters to drive the extrusion settings, and bingo, you've got a pointed extrusion that properly adjusts its depth to the wall thickness.

[laughingcreek]

I wouldn't have considered what you presented a bug.  On the surface it is behaving the way I would expect.

Most of us here are unlikely to ever notice because we wouldn't consider it a good way of achieving the end goal. 

After playing with it there does seem to be some unexpected behavior when going the other direction with the offset-

@jeff_strater -what do you think of the results in the attached file.

[dankG2KYJ]

@laughingcreek Gets strange when you make a simple sketch on the faces as well (black sketch lines are mine). 

[laughingcreek]

can't really tell what'g going on with out the model

[dankG2KYJ]

@laughingcreek  If you'd like I can re-create it. Something went wrong with my fusion and my projects yesterday, some files seem to be missing. I don't want to hijack the thread. If it is a bug, I was just seeing what else it was possibly effecting. If you want the file can I send it in a PM?