Is it considered correct to not demarcate internal joins with a line? To illustrate, here’s a screen grab I stole from one of DaveR’s videos:
At these “crease” points, I’m never sure whether to display a line or if I should hide/soften/smooth them.
I think its just personal preference, I would normally have a edge visible on any creases but this will also be impacted by the rendering (presentation) style you decide to use. I just find having the visible crease gives you more presentation options… eg no shadows, linework only still have 3d clarity.
PS… of course it also give you an edge and vertexes to snap dimensions to (which is always a dilemma when you want a chamfered edge for rendering but need a hard edge for nominal dimensioning)
If the join is not filleted I would show a line, just like in any corner.
I think it’s personal preferences. There’s a radius there and I prefer to soften those edges. You can see at the other end where the handle would attach that there is no fillet so I left the edges exposed.
It may be worth noting the difference between ctrl eraser and shift eraser, ctrl smooths the edge so it fakes the two faces into a pseudo curve whereas shift hides the edge without doing any smoothing, so you get a hard transition.
For me, it would be something to get picky about when you’re exporting an actual drawing set from the model. In the model, do whatever works best to present the idea without confusing the viewer. In the drawing sets, be as absolutely clear as possible with plenty of notes on radius, chamfers, etc. I haven’t had to model many parts where this would make a big difference in the end because I’m also the one machining them, so I could be wildly out of touch with the standard.
I do what box shows quite often. I’ll leave the line, but then when zooming out, or when preparing the export, I’ll come back and either hide the line or soften it, so it’s one fewer line.
That way the geometry is true but from a distance, it’s not overcrowded.
Dang, I didn’t know about that eraser functionality. Pro!
There’s a radius there and I prefer to soften those edges.
Right. (Old eyes didn’t spot that radius.)
i guess it wasn’t really presented clearly in the gif.
OK, kind of like blueprints vs display pictures.
Yeah, this forum is a great learning tool!
One kinda related point, how do you handle edges that are so close beneath a surface (but not on or part of it) they show through when zooming out? Hide them? That’s been my method, but again no idea if that’s the right way to do it.
Thanks for trying to making me feel better about my garbage eyesight. It’s really thoughtful. 
bleeding edges ? well before hiding them out, I check if they also bleed in the export. they often don’t (in my case at least), so it’s only an inconvenience when working.
if needed yeah, I can hide them with the eraser. or even hide the whole group if it’s not supposed to be seen.
I’ve had more cases of bleeding selections. I don’t actually see the edges under the surfaces, but when I’m far and I click on, let’s say a roof, it’ll select the piece just underneath.
Appart from zooming, no magic solution here. I’m just too far for SU to make a proper selection.
edit :
no line bleed, but as I’m far, I get selection bleed. a random click didn’t select the thin roof group (it’s slate, so actually thin layer) but the insulation underneath. no big deal, zoom in a bit, it’s all good.
Meanwhile @TheOnlyAaron dropping a video about hiding edges 30 min ago 
I taught him everything he knows.
I knew him when he was nothing and he hasn’t changed a bit…
(Tom Waits)
He used to be cool before anybody knew him but then he sold out. I don’t even wear the t-shirt anymore.
i always use a hairline to denote creases such as this. To render it as if it were a flush surface is deceiving and incorrect.
