Sweep face along curve but ...

Shoecorp · 28 Aug 2012, 13:46

Hello,
My clumsy searches in SketchUcation forums brought nothing, so I decided to post my question. Sorry if the answer is obvious ...

Here it is :

While trying to design a curved leg for a small table (Frank Lloyd Wright Coonley table which I uploaded to Sketchup's 3D Warehouse) I had to sweep a square face along a curve in order to generate the four resulting faces of the leg whose section is the original square.

Of course I tried the 'Follow Me' tool. Unfortunately the results were bad; the reason for this is because it seems that 'Follow Me' extrudes the face along the curve by keeping the original face orthogonal on each point of the curve.

My question : how do I extrude a face along a curve, while keeping it parallel to itself (normal to z-axis for example) while gliding along the curve ?

Thanks in advance for any help, and sorry again if the answer is obvious for anyone but me (I hope being smarter at woodworking than at Sketchup's usage !)

Olivier

TIG · 28 Aug 2012, 15:17

Look in the Plugins Index for FAK - Followme And Keep - this should do what you want...

Dave R · 28 Aug 2012, 15:56

The Coonley leg can be done with the native Follow Me tool. You need to do it in two Follow Me stages, though. One for the convex curves and another for the concave curves. I've got an example somewhere. I'll try to find it.

Dave R · 28 Aug 2012, 16:10

Here we go.

Working from the origin:

Leg blank. I'm working on the front left leg.
Draw cut profile for outer faces on inside face of leg.
Copy the first cut profile and use it to construct the profile for the two inside faces of the leg.
Run Follow Me on the first cut around the two outside faces of the leg. I preselected the outside edges on the top of the leg and then got Follow Me and clicked on the profile.
Repeat Follow Me operation for insides of leg with second cut profile.
Select all of the geometry, right click on it and use Intersect Faces>With Selection. Then delete all the unneeded geometry.

Coonley.skp

Shoecorp · 28 Aug 2012, 16:38

@dave r said:

Here we go.

Working from the origin:

Leg blank. I'm working on the front left leg.

Draw cut profile for outer faces on inside face of leg.

Copy the first cut profile and use it to construct the profile for the two inside faces of the leg.

Run Follow Me on the first cut around the two outside faces of the leg. I preselected the outside edges on the top of the leg and then got Follow Me and clicked on the profile.

Repeat Follow Me operation for insides of leg with second cut profile.

Select all of the geometry, right click on it and use Intersect Faces>With Selection. Then delete all the unneeded geometry.

Waoh !
Precise, quick and accurate answer. I'm quite impressed ! Thanks a lot for your kindness and dedication !
Olivier

Dave R · 28 Aug 2012, 16:49

Thank you!

FWIW, if you are a woodworker, you will probably appreciate thinking about the Follow Me tool for many operations in much the same way as a router. In the case of the Coonley leg that second cut needs to start before the "cutter" hits the leg. If you were using a router or shaper to make a cut, you would turn the machine on before the cutter contacts the work. The same idea could be used for drawing details such as stopped chamfers and moldings among other things.

Dave R · 29 Aug 2012, 11:37

Olivier, is it your version of the Coonley tables I found on the 3D Warehouse? It looks pretty nice. I found a couple of things that could be fixed but the bottoms of the legs look alright. It appears you made them differently than I did.

Shoecorp · 29 Aug 2012, 14:45

@dave r said:

Olivier, is it your version of the Coonley tables I found on the 3D Warehouse? It looks pretty nice. I found a couple of things that could be fixed but the bottoms of the legs look alright. It appears you made them differently than I did.

Yes it is. If you look closely at the very bottom of the outer table legs you'll find that the surface lying on the ground is not a square one which is not the desired shape. This happens simply because I extruded the upper square along the long 'vertical' curve of the inner edge of the leg, thus generating a surface with a square that was kept normal to the curve. So when you intersect the ground with the generated shapes you obtain a quadrilateral shape but NOT a square.

This is the reason why you method is far better, simply because, as you mentioned, you are thinking 'machining' with a router. I am currently working to reproduce your advices. Amazingly simple indeed !

I'm just struggling to keep an arc being an arc (!) and not a simple chain of edges (the lower part of the section cut) in order to generate 'sound' surfaces after the Follow-me operation around the corners. (Yours appear to be unique and plain, mine are a collection of connected shapes, making me suspect that my initial curve geometry was not so clean). But this is another issue ...

I'll upload a new version when satisfied with it. I'll add the url of the model in the warehouse if it is possible.

Thanks a lot again !

Olivier

Dave R · 29 Aug 2012, 15:18

Olivier, the curves get broken or exploded into the segments durning the Follow Me operation. In a case like this leg, that's not really a problem. Just make sure you copy the original arc before you run the Follow Me operation.