Joining polysurfaces issue

I’ve a couple of surfaces with edges created from the same curves and yet when I try to join them I get nada. The file is attached. Try to make a union of the two vertical (front/back) surfaces. I suspect it may have something to do with the tolerance settings used to make the surfaces. Both were made with the network of curves tool.

My setup:
Model Name: Mac Pro
Model Identifier: MacPro5,1
Processor Name: 6-Core Intel Xeon
Processor Speed: 3.33 GHz
ATI Radeon HD (177.7 KB)
Memory: 32 GB

Hi James - use MatchSrf, for Position, with Refine checked. Match the ‘front’ surface edge(s) to the two neighboring surface edges on each side.

Did that do it?


I found the MatchSrf tool but I don’t see the Postion or refine options you mentioned.

Here’s what I’m seeing -

That looks like you are still in the edge selection - get past that to the actual MatchSrf options. Any luck?


No luck. When I select an edge it’s all that will be selected. Here’s two more ss

To select the segment to match, you’d click in the same location along the edge , since there are two edges in basically the same place.

(Windows, but you’ll get the idea…)


You make it look so easy. I don’t have snagit installed yet so here’s a series of ss.

I clicked a second time on the edge and the result is bizarre

Yup- nearly there - there are two edges you need to match to, not just one - if you only pick one, the entire first edge gets sucked over to that one edge - so pick the one you did pick, plus the edge of the neighboring surface that is ‘in line’ with the first picked edge -Then let it do its thing.


I’ve been trying to set up a snag on the mac, but it’s a nuisance. I am clicking twice on the edge. The first highlights it and the second gives a direction arrow. It’s after that I click, get the dialogue box and finish.

Here we go

Try this:


Hope you haven’t given up on me. I sent you a vid of the issue.

Yeah- did you see my reply above? When you pick the edge again, it actually selects a target edge to match to - that is fine, but the edge being changed is much longer than the target edge, so don’t stop when you’ve selected that edge - select the next edge, above, that belongs to the adjacent surface.


DONE! I was just one click away from madness. Thanks Pascal.

I bought a copy of snag for Mac and I’m thinking it will be well worth it.

Well, I’m having more trouble. I rebuilt the model from the the beginning because it’s good practice, but again, I’ve come to the point of trying to fillet the edges and it’s very confusing. I’ve attached a screencast. Could you please educate on this?

here’s the modelDeoderant2.3dm (340.1 KB)

Hi James - if you cannot click on the edges to select them with FilletEdge, then the edges are not joined there.

You can get around that if the edges are too far apart to Join with MatchSrf as before, or, just ignore it and use FilletSrf. You may need to do some manual trimming afterwards to fit the surfaces in and clean up.

Note, for the bottom plane, if it is indeed planar, you might want to use PlanarSrf or Cap on the finished object rather than EdgeSrf or Loft as you have there. It does two things - makes a truly planar surface, and a simple one, and it allows you to verify that the area is planar - it is not, quite in your file, but it looks like it ought to be.


Thanks Pascal.

Regarding your points - I did try to do the match surface process on this model but it proceed the same way as before. I found I was able to join the surfaces anyway and assumed they’d be sound. I’m dismayed by the gap I left.

On the bottom, I had always used the planar from curves tool, but it wouldn’t work this time. Does having the Planar tab activated in the top menu bar have any effect on this?

Is there a ‘best practices’ document on modeling with R?

No… that is, if you are concerned about ‘naked edges’ then simply Joining will not be any guarantee - as you can see some edges can be joined, making a perfectly valid polysurface, but that’s it, it does not mean all edges are necessarily joined - for example, Explode a Box, delete two opposite faces and Join the rest - the Join is succesful, but there are, of course, unjoined edges. Use ShowEdges > Naked Edges to see where there are nakeds.


I’ve attempted to make a precise shape several ways now and each time I encounter an obstacle.

First, in an earlier iteration where in order to insure that the bottom edges were planar, I thought to use the extend surface tool on the objects and set up a split with a straight curve.

In that instance I could extend one but now the other!

Next, after re creating a surface from a network of curves, and a second opposing surface using the same curves to make the edges that are to be joined, when I attempt to join them, one of the surfaces cannot be selected.

It happens with both objects depending on which is selected first - the other cannot be selected.

All objects are selectable in the views mode and all appear to be correctly constructed, but again when trying to perform operations I’m stopped.

Even the match surface process is giving me unwanted results now.

I was able to make some planar curves on the bottom after rebuilding the surfaces, extending them and splitting them with a straight curve. But still everything else is failing.

I’ve sent you the current model and made a duplicate of the object I think is the problem.

I’ve little doubt the ultimate problem is with me, but logically I’m having a rather frustrating time of it.

Any feedback on the last?