Thread extension to blend with the OD

[kamil.malec94]

Hello,

Is there a way to extend the Coil by 180° in a way that the thread blends with the OD surface? I was thinking that I could use the LOFT feature, but I cannot seem to be able to execute it. Any feedback appreciated.  

Please see attached my F3D file. 

[etfrench]

It isn't clear what you want to blend to what.  If you want to extend the threads to the right end of the cylinder, edit the thread feature by adding more revolutions.  If you want to extend to the left end, edit the Plane 1 feature.  If you want to change the major and/or minor diameter of the thread, edit the thread feature.  If you want a non (Fusion 360) standard profile:

Create the coil with a square profile.

Create a Plane on Path at one start corner of the coil.

Create a sketch on the plane.

Draw your custom profile.

Use a sweep to complete the custom thread.

[mavigogun]

It's all about locating the rail, right?   First you'll need to create a spiral Face that matches the progression of your coil- then intersect the spiral with a silhouette (Profile) of the path as viewed from the end of the cylinder; luckily, that path is a simple 2 Point Circle plotted from the thread bottom on one side to the cylinder outside surface opposite.   I think the spiral Face might be made with just 2 lines and a Sweep twist.    This will be fun- I'll get to work.

[mavigogun]

...and a screencast.   It's late, I'm tired, so excuse the stammering.   Here's a picture of the solution.    Oh- and do your civic duty: the polls are open- vote.

[mavigogun]

Double Post

[etfrench]

As a thread, tapering to the OD won't work.  Perhaps this is for a bellows?

[mavigogun]

Duh!   True, that- unless the nut is made of silicon.    I have no clue what it is then.    No more Fusion after midnight.

[HughesTooling]

Here's another way using a solid sweep and a couple of parameters. One thing to note about coil is the section is not perpendicular with the helix so the section is slightly squashed. 

In my example I've rotated the end faces to make them perpendicular with the coil using the HelixAngle parameter then used a sketch to construct a centre line for the sweep. This got a bit complicated because the coil centre line and the cylinder had different diameters, see LeadOutDiameter parameter. See attached file.

Mark

[mroek]

@HughesToolingOut of curiosity, I looked at the document you provided. Interesting technique to achieve this, thanks for showcasing it. However, there is something odd when I look at the two face move operations in the timeline. The value you used (which I know is a calculated parameter) to rotate the faces doesn't show up, all boxes are populated with zero. That might be a bug, I think. Maybe @jeff_strater could take a look at that and see if he observes the same? Just open the document and double-click one of the Move operations in the timeline to edit it. Press CTRL to disable the preview, and when releasing it, you can see the face move. Yet, the value is still zero.

This is also rather slow on my machine, so it feels like this move operation is computationally intensive.

[HughesTooling]

@mroek That is the way Move works, really I should have use the Rotate option then the move is parametric but you need an axis to rotate around.

Attached is another version using draft to align the end faces so they're perpendicular with the helix.

Mark

[mavigogun]

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@HughesTooling wrote:

Here's another way using a solid sweep and a couple of parameters. One thing to note about coil is the section is not perpendicular with the helix so the section is slightly squashed.

Great learning tool- thanks, Mark.

Can you demonstrate/quantify the squash? I suppose I could run the Sweep without offsetting the Circle for the Intersection Curve Projection on the helix, Split the Body where it passes a half rotation, and compare the profiles. If very, very similar, it may be difficult to distinguish between deviation introduced from Sweep Profile orientation and Projection guestimates. It's a mystery to me how Fusion handles the Surface Guide aspect of the Sweep. I assumed with a regular Path and Surface the results would be absent all but fine numerical distortion- but that's just because I view all such things as magic. I don't really understand the process, only confront the results.

[mroek]

Ah, you're right. A translate/rotate move is parametric, while a "Free" move is not. That really is a weakness, I think.

Using a draft like you did is also of course possible, but you can even avoid the whole calculated parameter if you create a plane along path (coil is the path) and then use "Replace face" with this plane and the face.

[HughesTooling]

@mavigogun The squash is caused by the coil, you can see it if you create a very coarse pitch.

It probably doesn't matter with a thread but good to be aware of the problem. See attached file for a coil generated using a sweep with the profile alined with the helix, how it should be done.

Mark

[HughesTooling]

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@mroek wrote:

Using a draft like you did is also of course possible, but you can even avoid the whole calculated parameter if you create a plane along path (coil is the path) and then use "Replace face" with this plane and the face.

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@mroek Thanks for the tip but when I tried it didn't work, am I doing something wrong? Create a plane along path at the start or the coil then when I replaced the face most of the coil disappeared!

Mark

[HughesTooling]

@mroek OK, figured it out. If I select the helix made at the bottom of the cut it fails but if I select either helix at the cylinder diameter it works.

This path fails????

Mark

[mroek]

I'm observing the same thing. That's most definitely a bug. I also tried the following:

1) Create the plane along path and choosing the helix at the bottom of the coil as the path

2) Extrude the face a small distance (cutting a bit more into the solid)

3) Then replace the face of the extrusion with the construction plane created

This works, because the face after extruding isn't the same as the one created by the coil cut operation, even if it is parallell to it. But again, it should have been possible to replace the orginal face as well, without most of the coil disappearing. @jeff_strater, take a look at that if you can.

[mavigogun]

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@mroek wrote:

This works, because the face after extruding isn't the same as the one created by the coil cut operation, even if it is parallell to it. But again, it should have been possible to replace the orginal face as well, without most of the coil disappearing. 

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Hummmm.  UnStitch,  zero Offset Face, Delete the original- might preserve the original geometry... wonder if it would have the same outcome.

[jeff_strater]

@mroek, regarding editing the face moves.  This operation was done with "free move", and this type of move does not retain any values.  Had this Move use either Translate or Rotate, the values would be remembered.

[jeff_strater]

@mroek,

I'm not following the workflow/problem here.  Can you illustrate with a screencast?

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@mroek wrote:

I'm observing the same thing. That's most definitely a bug. I also tried the following:

1) Create the plane along path and choosing the helix at the bottom of the coil as the path

2) Extrude the face a small distance (cutting a bit more into the solid)

3) Then replace the face of the extrusion with the construction plane created

This works, because the face after extruding isn't the same as the one created by the coil cut operation, even if it is parallell to it. But again, it should have been possible to replace the orginal face as well, without most of the coil disappearing. @jeff_strater, take a look at that if you can.

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[mroek]

@jeff_strater

I haven't installed the screencast software (I'm extremely wary of installing any such software), but attached is a document (based on the one @HughesTooling made), where I did the steps I outlined (replaceface_workaround.f3d).

But again, that's not a proper method to do the replace face, it should most definitely have been possible to do it on the original face. I also attached a document where I did just that (replaceface_fail.f3d), and where most of the coil cut then disappears. That is a bug I think, since the face being replaced should not affect any other faces in the model. If you use a different path for the "Plane Along Path" (as @HughesTooling also mentioned), then the issue disappears, even if the plane created is exactly coplanar with the first one (and thus should do the same thing when used in the "Replace Face" command).