Sweep Unexpected Twist

[kojiai]

I'm trying to create a basic 'rib' along the top surface of a part. However, Solidworks can't seem to correctly resolve the path and I get "Sweep resulted in topologically invalid body" error.

I have the path as a 3D sketch along the surface of the part, and the profile, a simple square, perpendicular to the path. When the sweep is created, it begins to unexpectedly twist as it moves along the path around a corner and over a curve, as shown in the pictures. I'm not sure why this is occurring, but I suspect this is causing the error, and even if it's not, it's not what I intend.

For 'options' I have Orientation set as "Follow Path", and Path Alignment type as "Minimum Twist". I have tried just about every other combination of setting without any improvement.

Any ideas on how I can resolve this?

 

[MartinShane]

I was working along a similar path using surfaces before seeing CBL reposted a solution. Here is how I was going about it, late to the party though it may be.

 

[CorBlimeyLimey]

Here's a much simpler method.

 

[CorBlimeyLimey]

... and even simpler.

 

[MartinShane]

Interesting CBL. I play in surfaces a fair bit, and never used the intersect feature before. I'll have to look at that closer as it seems like at the very least it can eliminate a step in the model tree compared to my standard routine of knit + combine.
In the interest of seeing how few steps this could be done in I modded your Sketch 1 and took out the surface extend to simplify a bit further. As a thought exercise I'd be interested if anyone gets it down simpler than this. With CBL's method its down to 5 items in the model tree, including the new reference plane.

 

[CorBlimeyLimey]

How about 4 steps.

 

[CorBlimeyLimey]

... or 3 steps

 

[MartinShane]

And the added plane I guess doesn't have to be there, so 3.

I Have a hunch that it could be done with 2 features, using just a boundary surface and the intersect, Possibly 1 with a boundary boss/Base feature. Both of those would require additional sketches though, so there'd be more work involved than this method.

 

[MartinShane]

OK... so what, I have to refresh every time right before I post to make sure CBL hasn't already reposted what I was doing???

 

[kojiai]

You've blown my mind. Surface extrudes, offsets and intersect?! Never would have crossed my mind.

Thanks for all help and effort from everyone. This has been a really interesting lesson.

 

[kojiai]

Okay, I have yet another question.

Clearly this 'ridge' needs to interface with another piece. So now I'm looking at doing the inverse, rather than an extruded shape, it's a cut shape into the part. I've been playing around with it, but putting surfaces inside another part is somewhat pointless. What's the best way to proceed with this? Thanks!

 

[CorBlimeyLimey]

putting surfaces inside another part is somewhat pointless

Not so! Use those surfaces to create a non-merged solid body, and then use the Combine function with the Subtract option.

Or you could use the Insert > Part function to insert the part with the rib, into the part needing the recess (multi-body part), and then use the Combine > Subtract method.

Or you could use the Insert > Part function to create a multi-body part (of the parts without any rib or recess) and then use the Rib tool twice (once on the inside edges & once on the outside edges) to create the rib and recess ... maybe.

 

[kojiai]

Thanks for the tips. I'm trying a combination of them, but the Combine option is always greyed out. I was playing around witht he subtract option earlier, but it always removed something that I didn't want it to, so I'm likely setting it up improperly. I'll keep playing around with it, but any other tips are appreciated. Thanks!

 

[CorBlimeyLimey]

kojiai,

Find a local SWUG (SolidWorks User Group) in your area. Your VAR should be able to help locate one for you. If one exists there will be other SW users there who should be able to help you. Your VAR should also be able to offer some training.

The Combine tool is only available in multibody parts ... not assemblies.