# Helix cut out in a tube

**URL:** <https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918>\
**Category:** Modeling Questions\
**Created:** [January 18, 2024, 7:05pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918 "2024-01-18T19:05:47Z")\
**Posts on this page:** 13\
**Page:** 1

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**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 18, 2024, 7:05pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/1 "2024-01-18T19:05:47Z")

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Hello friends,

I am suffering with this problem for a while. As I am not an industrial engineer - designer but a hobby designer I am not sure if this is even correct thinking.  
I am trying to creat a “ Helix cut out” in the tube, where the cut walls are “PERPENDICULAR “ to the tube’s centre axis. So if I would drill a hole 90 degree to the axis and would move up a notch -turn the pipe few degree and keep drilling that way I should always have a wall perpendicular to the centre. When I design a helix shape to “subtract “ from the tube, the walls are “twisting” According to the helix concave walls.  
The “PIN” which needs to be riding in this opening is touching ONLY THE INNER OR OUTHER EDGES of the walls.  
I understand the reason for this, but is there a method in the industry - (designing) like as per CNC machining where the cutting bit would be stationary and the tube would move and rotate around the axis? That would make the walls aligned ? Thank you all for the input, if any 🙂 Ed.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/d/9/d9b0a58af7556c27494098bce653388d70afc1fd.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/a/d/ad041ae1b7bdccfe4c9a8dc26cc2430d77366211.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/f/6/f6248d8e5211d9bc26be4ce2a666284a9e11f663.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/e/7/e70206ab4e0e931fd8d03126943b7664f88c10b3.jpeg)

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**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [January 18, 2024, 7:25pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/2 "2024-01-18T19:25:22Z")

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**Project** a sketch on the surface of the cylinder which creates an edge. **Extrude** inward and the walls are perpendicular to the tube axis.

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<div class="post-metadata">

**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 18, 2024, 7:48pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/3 "2024-01-18T19:48:31Z")

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Many thanks. I was trying to do this too. But had problem with aligning the shape if I needed to go 90 degree from start to finish. The opening was tapering on me? But I will try again to see if I am wrong somewhere. Will report soon. Once more thank you and have a great week. Ed

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/e/f/eff0fb4fe80d609f02ef0bd79ea47603ca11dceb.jpeg)

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**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 18, 2024, 8:35pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/4 "2024-01-18T20:35:51Z")

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Hello Mike,  
Just a correction here - I am trying to have the cut 180 degree not 90!

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**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 18, 2024, 9:00pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/5 "2024-01-18T21:00:02Z")

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Here is my problem when trying to project the lines onto the cylinder. The ends spread out. ☹ ?! I need 8 mm from one side to the other side. Thanks

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/d/f/df3ab7c07dfb16ad803f977af40088fdea41a8fc.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/7/5/75631104d48f0d7162f2e5da7479cbac355ee7c4.jpeg)

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**Author:** ![Bob3DPO](https://avatars.discourse-cdn.com/v4/letter/b/7993a0/32.png) [@Bob3DPO](https://discourse.shapr3d.com/u/Bob3DPO)\
**Post date:** [January 18, 2024, 10:19pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/6 "2024-01-18T22:19:24Z")

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Hi Edward,  
Here I made a helix by revolving a square about an axis 180 degrees and giving it some height. Then I subtracted it from a cylinder tube. I don’t think it is “twisty”… The video is a series of undos as I needed to keep the file size down.

  
 ![IMG_0490](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/e/1/e1ccdded882e9ae983f1ea27f56a3db2855d92d5.jpeg)

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**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [January 18, 2024, 10:20pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/7 "2024-01-18T22:20:13Z")

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Here’s a 180° cut. The width of the **parallelogram** sketch = the diameter of the cylinder.

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<div class="post-metadata">

**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [January 18, 2024, 11:15pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/8 "2024-01-18T23:15:10Z")

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@Bob3DPO, really nice approach!

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<div class="post-metadata">

**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 19, 2024, 12:41am UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/9 "2024-01-19T00:41:17Z")

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Thank you both for spending time on this. Appreciate it.will update with result.

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<div class="post-metadata">

**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 19, 2024, 3:22am UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/10 "2024-01-19T03:22:12Z")

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Back again.  
So once more here is the issue I can’t resolve and probably it’s just not possible due to the geometry.  
You can see the differences in the shape of the helix body. It does not stay with the same dimensions . Also the top / bottom of the helix is offset to the axis.  
It’s a hard project to solve.  
But thank you all for you input and support.  
Ed.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/4/0/40feab5cf0bcaea15c92b262a3c6b7ac1640dde3.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/f/6/f6d6e48eb37039aa4eb448ba814a10b9993cff52.jpeg)

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<div class="post-metadata">

**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [January 19, 2024, 4:03am UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/11 "2024-01-19T04:03:53Z")

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Here’s a better approximation. Angle the sketch before doing the **Revolve**. Adjust the height of the helix so that it is normal to the angled sketch (as best you can). Still not perfect.

Or, if the height is a given, adjust the angle of the sketch accordingly.  
In the end, maybe the height of the sketch needs to be 8mm+.

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<div class="post-metadata">

**Author:** ![Bob3DPO](https://avatars.discourse-cdn.com/v4/letter/b/7993a0/32.png) [@Bob3DPO](https://discourse.shapr3d.com/u/Bob3DPO)\
**Post date:** [January 19, 2024, 4:56am UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/12 "2024-01-19T04:56:34Z")

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I think @TigerMike is right, the sketch needs to be bigger than 8mm, Maybe try this: use Shapr3d to help you figure out the height of the sketch. Draw a line that is the slope of your helix. Make a parallel line 8mm from that. Draw a vertical line with endpoints on each of the parallel lines, and use that measurement as the height of the face you revolve. Here is an example with 55 degree slope showing you would need a square 14 mm (giving a small clearance, you may want more…)

 ![IMG_0493](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/e/8/e89f22da83b137bfd664488d4b4b6ef3b2b81ae0.png)

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<div class="post-metadata">

**Author:** ![Prototyping](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/prototyping/32/14094_2.png) [@Prototyping](https://discourse.shapr3d.com/u/Prototyping)\
**Post date:** [January 19, 2024, 10:16pm UTC](https://discourse.shapr3d.com/t/helix-cut-out-in-a-tube/29918/13 "2024-01-19T22:16:01Z")

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Thank you again! Will be experimenting.