Can't even make half a dang dome

hellnbak

Something as basic as it gets, just trying to make half a dome. Should have taken maybe a minute. Yeah, right.

Everything is symmetrical, colored edges by axis and there's nothing weird about it.

Until I click follow-me --

When I make it a full circle, everything's fine

Yeah, I know, I could just delete half of it and move on, but I would like to know why it's doing what it's doing.

The SKP is attached.

Untitled.skp

TIG

When using FollowMe around a partially circular path you need to ensure that the profile face is perpendicular to the first edge [segment] in the path.
If you start at a 'node' it won't be.
If you start at the midpoint of a segment it will be.
So draw your full circle path and then add a line to half it...
BUT not from node to node but rather drawn from the mid-point of the segments.
Erase the unwanted parts and perhaps rotate the remaining semi-circle so it is orthogonal again
Then arrange for the profile to be perpendicular to the end [half] segment.
The FollowMe surface generated should now be correct.

Alternatively [as you discovered] make a whole sphere and with hidden geometry on erase half of it to leave a hemisphere.

OR make the profile from a half-circle and then make a quarter face.
FollowMe that around a circle - you'll get a proper 'dome' that way.

OR use EEbyLathe [or a similar tool] to make a true swept extrusion through any angle [it'd be 90 degrees for a half-sphere] - from any profile around a picked axis... The 'end-facets' are auto-corrected to suit...

cotty

Ok, too slow for TIG and Dave, but here is an image ...

hellnbak

Crap, I knew all this. It was explained to me years ago, right here on the forums when I was just starting out. Have used it many many times.

My apologies. I think my brain is getting too old and tired for this stuff.

I'll just go back to bed.

TIG

I didn't bother with an illustration - a thousand words paint a picture

hellnbak

Just another old fart's brain fart. Anybody know of a cure for cerebral flatulence?

Rich O Brien

@tig said:

I didn't bother with an illustration - a thousand words paint a picture

@unknownuser said:

Just another old fart's brain fart. Anybody know of a cure for cerebral flatulence?

Marriage?

hellnbak

@rich o brien said:

@unknownuser said:

Just another old fart's brain fart. Anybody know of a cure for cerebral flatulence?

Marriage?

if that's the cure I'll just put up with the flatulence

Mike Lucey

@hellnbak said:

Just another old fart's brain fart. Anybody know of a cure for cerebral flatulence?

I know the feeling. As for a cure ..... there is none ...... its a case of just plodding along.

cotty

@tig said:

I didn't bother with an illustration - a thousand words paint a picture

hellnbak

@mike lucey said:

@hellnbak said:

Just another old fart's brain fart. Anybody know of a cure for cerebral flatulence?

I know the feeling. As for a cure ..... there is none ...... its a case of just plodding along.

Yeah, I suppose. Plodding gets real tiresome after a while, though.