Helical Protrusion Parallel to the Axis of Revolution 2

[random_guy]

Hi All,

I am trying to create a helical protrusion along the inner diameter of a cylinder. The problem with using the helical protrusion tool is that the cross section needs to be sketched perpendicular to the axis of revolution. I need to sketch parallel to the axis of revolution.

I thought I could generate a datum curve and then create a sweep, but that isn't working out well. Here is the datum curve and the datums I am referring to:

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/DatumCurve.jpg

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/DatumCurvewithDatums.jpg

The helical sweep creates "kinks" in it, and it also only allows me to sketch perpendicular to the end of the spline, instead of on the front plane. The sketch comes out wrong due to this issue.

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/HelicalKinks.jpg

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/HelicalKinksFront.jpg

I'm hoping someone has dealt with this problem before and knows an easy solution to the problem.

Thank you in advance for any advice you can give.

-Nick

 

[dgallup]

Do you mean like this? I have no idea what sort of shape you want to sweep so I just made a circle.

 

[random_guy]

Mr. Gallup,

Thank you for taking the time to generate that model. Unfortunately, the model seems to have the same issue I was having - the circle is drawn on the correct plane but since it follows the trajectory of the curve, it is completely distorted. What I would like is for that circle to keep it's shape throughout the entire length of the curve. The circle would remain perpendicular to the axis of the cylinder.

I attached a few screenshots showing the distortion.

This is the correct way I would like the sketch oriented:

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/protrusionfront.jpg

But notice the circle follows the path of the curve:

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/protrusionside.jpg

A side view with hidden lines demonstrates this even further:

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/protrusionsidecrosssection.jpg

Once again, thank you for your help. I hope with this bit of information you will understand what I'm shooting for.

Thank you,

Nick

 

[dgallup]

What you are saying is contradictory. In the model I sent the circle is perpendicular to the axis of the cylinder. This will NOT create a round sectioned sweep. I've attached another file with the circle section normal to the sweep.

 

[RBobroski]

Wouldn't a VSS work, setting the section to be constantly normal to the surface of the cylinder?

 

[random_guy]

Mr. Gallup,

Thank you for your help. The previous part file is exactly what I'm looking for. However, I cannot re-create your method. I am on Wildfire 5 and I believe you are on an earlier version or pre-wildfire version (due to the "protrusion id" label). Can you please explain how you achieved this result?

I tried numerous methods to no avail. I would still like to be able to use the datum curve I generated, but when I try to select the curve using the sweep tool I get the message:

"Specified trajectory is not valid. Please reselect."

Thanks again,

Nick

 

[aafuni]

Use a VSS. I'll post a model in a jiff.

 

[aafuni]

Here it is. VSS work great even when the sections aren't variable. They give you a lot more options as far as sketch orientation and trajectory.

 

[random_guy]

I tried using a VSS, but as soon as the curve reaches the middle of the pipe (180° revolution), the section flips and moves to the outside of the inner diameter, eventually extruding though the pipe and popping outside of the outer diameter.

Here is an image of what I am talking about:

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/VSSOutsideofpipe.jpg

 

[random_guy]

Thanks aafuni,

I checked out your model and I see that it has the same problem I experienced earlier, where the circular cross section is not maintained. See the image below:

http://i941.photobucket.com/albums/ad260/nsgoldberg/Pro-E/protrusionsidecrosssection.jpg

I would like the cross-section to remain perpendicular to the path of the trajectory (I incorrectly phrased this earlier, which led to some confusion).

I appreciate the help,

Nick

 

[RBobroski]

Are you using the centerpoint of the circular section as the trajectory start point, or are you picking a tangent edge? I can't really tell from the given images.

 

[aafuni]

Isn't that the easy way to do it? Why wouldn't you just draw the sketch on a plane normal to the trajectory then (the default sweep, not vss)? You can either use sweep, and define your section within the sweep command (super simple) or you can use VSS and select constant section normal to trajectory (also super simple but with an extra step).

 

[aafuni]

And in regards to the VSS, look at my settings, your image shows a VSS with different tangency control than what I sent you.

 

[aafuni]

RB, it doesn't really matter which you use, it works with either, just define your sketch within the sweep menu and create the circle perpendicular to one of the reference axis created in the sweep sketcher interface.

 

[dgallup]

You could just make this shape with a standard helical sweep normal to trajectory.

 

[random_guy]

Got it working.

I followed the steps in aafuni's VSS file. Turns out Pro/E will not use a datum curve, it must be a sketch. A little trig and I got that working. Also, the sketch had to be inside the cylinder by a distance equal to double the thickness of the cylinder. I sketched the shape of the helical feature and it looks beautiful.

Thanks for all the great help. It's greatly appreciated!