Hollow helical gear

3D Design Volume Model
1

Hello
I'm looking to make a hollow helical gear (for a straight worm and wheel assembly). I'm having a problem in the Solid design.
Having talked to someone who knows quite a bit about gearing, the trajectory of the tooth profile is a spiral which itself is wound around a circular trajectory (1st drawing attached). If we take the wheel itself as a reference, of course.

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The models I find on the net simply rotate the sketch of the tooth profile around an axis. Which for me does not take up the rotation of the wheel during its " machining " and creates a gap on the bottom of the net at the level of the wheel cheeks.

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Is it possible to push a propeller to follow a curve rather than a straight line, as a guiding axis? If not, what solution would you have?
Thank you and have a good day

2

Hello

Yes, it is possible to do what you need.
I invite you to check out this fantastic tutorial:
Using propeller and deform functions - myCAD by visiativ.

I think you will find the solution there.

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3

Hello

I'm not sure I understood your request, but if it's something like this that you need, I'll explain it to you.
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4

Yes, it's a bit hot to explain. It's that kind of thing, yes

5

To sum up: you have to scan the profile according to the circular trajectory with the " Specify a twist " option.
Personally I will try with an arc of a circle of length corresponding to 720° (2 turns) then a circular repetition with the geometry repetition option.

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6

What I don't understand well is this part:

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I explain how to do it in this little tutorial. See if it corresponds to what you want:

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8

Hello.

If you want to be realistic, you must:
1 Drawing the shape of your machining tool in 3D (your milling cutter): a revolution
2 Sweep this shape to do the machining of a tooth (with the options that work well for your scanning: it depends on the way of machining)
3 Repeat this scan to get the right number of teeth

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9

That's what I would have done intuitively, but I have the impression that he's looking for more " complicated ".

Because for the time being, my tutorial is only realistic if it's machined by an endless tap with a linear rotation of the wheel and the tap during machining. This creates deformities on the edges of the teeth, and my tutorial reproduces this effect, at least I think.
It deserves a little movement study to check that.

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10

Sylk
That's exactly what I wanted. I didn't know that sweeping allowed for this kind of thing. A huge thank you!
After that, I'm not a gear expert, I do a retro on a material that we were given and I'll see if the scanned model will match with the solid 3D.
For me, intuitively, we would have a discrepancy between a material removal (having the profile of the tool) with a revolution around an axis (straight axis), and a material removal with your technique with a material removal (still with the tool profile) but with a revolution along a curve, as you did. It's quibble or not, I wanted to get as close as possible to the existing one.

Closed subject for me. Thank you again :smiley: and have a great day to everyone who took the time to respond.