When do you weld?

Do you weld all edges all the time? Do you wait until a model is complete and then weld everything, or do you weld all edges in individual components as you progress through a model?

I generally only use weld when I’m going to push/pull something so I don’t end up with a bunch of lines from edge joins, but it would be interesting to know of other reasons to weld.

I rarely weld. Weld arrived late in my use of SU, and I was used to smoothen stuff afterward anyway, either globally (with the soften / smoothen panel) or with the eraser.

I know I should try eneroth’s auto weld, that can weld stuff pretty much automatically. But even when I weld and smoothen stuff, I often end up turning hidden geometry on during the modelling phase. Plus sometimes the lines created by not welding are actually useful to model further :slight_smile:

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I weld edges when I’m modeling pipes. I make them with profile builder and I like pipes to be split by zones but not in curves

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I almost never weld anything. My model components are intended to show the item’s construction, rather than to yield a photorealistic appearance. Thus, I usually show the joints between curved and straight rigid tubing, the borders of fillets and outside-edge radii, etc. Electrical cables are an exception that get a smooth exterior without visible joints between arc or spline and straight segments (because the original cables that I am modeling were somewhat free-form in their final shapes, so I am not trying to match the originals perfectly). Thus, I will weld the edges forming the cable’s centerline path prior to Push Pull.

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Different strokes. I weld edges frequently for a variety of reasons. Before extruding is just one. Welding edges for paths is especially useful because it makes it easier to select the entire path.

Boolean operations will explode circles and arcs into their individual edge segments so after running a Boolean operation I run Auto Weld which converts circles and arcs back to their original state which is important to me for inferencing.

When troubleshooting models of complex patterns for others as when they can’t get faces to form, welding edges makes it easy to find gaps and forks in the loops of edges.

And I weld edges before output when using sketchy styles. That has a huge impact on the appearrance of parts with curves. I exploded the curves on a bunch of the parts in the right hand copy of this steam engine.

FWIW, Weld has been around in plugin form since at least 2004.


I weld only when curves get exploded, for circles and arcs that have also been exploded by any reason I use curvizard to reconvert them to arcs and circles so I can be able to change the segments. I have assigned a keyboard shortcut to a clean up feature that fixes edges if they’re split instead of welding them.

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Do you ever get anxiety right before enabling hidden geometry? That terror of seeing a whole bunch of new cobwebs…

The model I’m working on has few pipes (actually tubing, I guess) but it was some of the first stuff I modeled and much of it is, frankly, kind of a disaster. Mostly that’s due to making the circles from a ludicrous number of segments. Live and learn, huh? At some point it’ll get completely replaced now that I almost have half a clue how to do it right.

Are these original designs, or replicas/reconstructions of pre-existing things?

Welding edges for paths is especially useful because it makes it easier to select the entire path.

Yes, it took me a while to learn (stumble upon) this and it made life so much easier than “shift click click click click click click click click click click click…”

One time I took a look at the work on your personal site. After a few minutes I had to go lie down for a while. Rarely have I felt so inadequate. :neutral_face: :grin:

Can you explain for me the difference between fixing split edges and welding edges? My knowledge is laughably limited.


Please don’t look at my models that way. Consider that if I can do it, anyone can do it. Even you. :wink:

Thank you for the compliment, though.

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Digital reconstructions of actual hardware, for example:



Sometimes straight lines can be split by different reasons, if you weld them you’ll have a curve, if you fix it you’ll have just an edge, there are different ways to fix them, you can draw a line from an end point on the edge and then erase it, that will also delete the end point and you’ll have just a straight edge, but it’s easier just to use the fix edges feature in Thom Thom cleanup3, it will automatically fix all the straight lines that are split.

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It took a while to figure out why I had edges/lines disappearing after using cleanup! It was pretty annoying if I didn’t notice at the time and later saved several iterations of the model, only to have to go back and find the last one that still included the now deleted edges. It taught me to not leave edges lying around by themselves. :grin:

I weld when appropriate.
This is a little vid I made recently to explain one of the uses for weld.


But there’s an option to just fix the edges without clearing up the rest of the model. I’ve created shortcuts for both fixing edges and cleaning up using last configuration, it saves me a lot of time.

If a model has an edge that is just that – a bare edge – doesn’t cleanup usually delete them? Or is that only if Erase Stray Edges is enabled? That option has saved me a huge amount of time I used to waste doing it manually.

Yes, only if that option is enabled, but cleanup has another feature that doesn’t run the entire cleanup on the model just fix the edges and nothing else, you can check this going to extensions/Thim Thom’s extensions/cleanup3/Repair edges. It’s the last option on that menu.

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