Everyone went to sleep ... had some time to spare....
A: Ellipse are no simple entities. Darwing them is one, doing math on them is harder as you might think.
B: Offset is not always flawless in Qcad. -> Countless reports and discussions.
C: Offset of a multi selection sometimes end premature -> bugreport.
D: The Booleans you mention are no easy task to code.
They may look simple in one case but universally it is something else.
That is what we have to work with untill things get better.
Every bugreport can be a step forward.
As in your former design I see some symmetry what also means that we don't have to stretch it to the limits.
So I divided your problem up in pieces.
Pitty I did not have the ellipses. They were exploded in 32 arcs.
The accuracy here is size relative and in this size the 32 is rather coarse.
Second problem is that some of them aren't closed forms.
Qcad will try to offset closed forms with a closed form, it will not necessarily do that for an open form.
So I copied the entities of your second challenge and put them in a new document (Layer _Org)
There is no reason why or why not dead center.
I defined a cropper as guideline (Layer Cropper)
Duplicated Layer '_Org' (YY) to a new layer 'b Restant ...'
Hint: Always try to keep your original entities aside... there is no way back from exploding splines or ellipses.
Selected all on layer 'b Restant...' (Y+)
Activated Crop To Rectangle (CLR + clip to Area) and pointed at the corners of the 'Cropper'.
Aside from cropping them the polys get exploded too.
Recombined with Polyline from selection (OC).
Added an offset layer 'c Offsets' (YA) what becomes active on creation.
Tried some offsets (OQ + Whole, Round
, Clip) followed by undo just to see what was comming....
Hint: The larger te offset value, the less details that will remain, 5 is huge.
Rule off thumb is at least 3 times smaller then the smallest detail needed.
You can find the two indication points that worked best in a sublayer.
Left one first and then its obvious to select a bulge that wasn't offsetted.
Isolated the bad offsets in an other sublayer.
Seeing it is believing it: Bad offsets.
Selected the outer strings, duplicate (DP), added layer 'd Isolate...' and changed the 'General propeties' of the selection to that.
(That's just my way to do this in one go)
Recombined the outer offset strings with Polyline from selection (OC).
Mirroring this and I am halfway in creating the offset outward.
The bottom half can be done in the same way.
After some trimming and recombining to one outer offset the last instruction will be a single offest inwards.
(OQ + Whole, Miter
Like I said:
CVH wrote: ↑
Sun Dec 22, 2019 11:19 am
It's a long way around.
And because of the poor approximation:
CVH wrote: ↑
Sun Dec 22, 2019 6:34 pm
Very bad result too
But in the end I will get there.
And if all fails there is still 'Break out segment' (D2) and lots and lots of clicking.
Use it near the outer boundary and In a 100 clicks or so ...
QCADpro 188.8.131.52 / win7pro 32 bit / 4GB / 1e generation i7 2.6Ghz / HDD GeForce GT 520