How to Extract Srf & MatchSrf - Demo by Brian James modeling a sink


My question is regarding a YouTube demo by Brian James modeling a sink.

He demos the use of gumball and shows how to create the water tap.
He starts with a simple sketch and in the process shows the use of ExtractSrf and MatchSrf.

My problem is that I can’t figure out how he created the first profile sketch and and how he ended up with an untrimmed surface. MatchSrf only works with untrimmed surfaces and I can’t figure out how he did that.
Maybe someone in this forum can explain it to me.

I appreciate any help.



Do you mean the Cntrl and drag to make the solid?
Not sure if current one can make a solid in one go from a closed curve…

@BrianJ did usage change along the way maybe? or some setting somewhere?

Hi Toshiaki,

If you look at the iso curves you can see that it is a single span surface not a polysurface.
MatchSrf requires a untrimmed base surface. I need to know how he modeled the very first sketch & surface before the initial base extrusion. Since this surface needs to be an untrimmed Surface or else you can’t use the Matchsrf command later on.

So in other words, how did he manage to get a single span suface (not a trimmed surface!) from the sketch in the first image. And what curve type was used to sketch the base contour.

Hope that explains it better



I wasn’t able to see the whole webinar as it got stuck, but I see…

Not sure how he got a untrimmed surface then…

I guess you can try like railrevolve to get a planar untrimmed surface. Not sure if this helps…
Other I guess a loft to a point would also do.
railrevolve.3dm (32.0 KB)

Not sure this helps with your question.

MatchSrf can use trimmed surfaces. The edge to be matched of the surface to be changed has to be untrimmed. Other parts of the surface to be changed can be trimmed. The surface to be matched can be trimmed.

Hi Toshiaki,

The loft to the Point was the ticket.

Thanks for the help.


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The planar surfaces in the video are trimmed surfaces. They are not changed using MatchSrf so do not have to be untrimmed. The surfaces which are changed using MatchSrf are untrimmed.

Hi Elmar,

It’s been a long time but I bet I drew the initial curve as one continuous profile using Grid snaps. Hope that helps.

Thanks…It seems that you need to use loft or the like to make it a single span surface.