3D solids melting together

weedywhizz

Hi,

I'm trying to align a 3D solid next to another solid while extruding but once I do that, they melt together into 1 piece.
How can I stop this behaviour ? I don't want to leave room between those soldids like 0.001mm. I want a snug fit.

Any ideas ?
Thanks
Steffen

Louis_Verdonck

The DMEXTRUDEMODE system variable controls whether a new solid is created or unified.
DMEXTRUDEMODE = 0: solids created when extruding a contour lying on the face of the solid are united.
DMEXTRUDEMODE = 1: create separate solids

weedywhizz

Thank you Louis,
that also means that a new solid is being created. I want the extruded piece to stay a single solid though.
Any other options ?

Cheers
Steffen

Louis_Verdonck

Please have a look at the dmExtrude command in the BricsCAD Help under Command Reference / Direct Modeling / dmExtrude, more specifically 'Command Options / Auto'. The DMEXTRUDEMODE system variable determines the behavior of the Auto option, repeatedly hitting the Ctrl-key allows to choose another option.

weedywhizz

Unfortunately none of these modes work the way I want it.
"create" is the only mode that works but does what it says - it creates a new solid but thats not what I want.
I I unite the created solid with its parent solid it again - melts the solid next to it as before.

Louis_Verdonck

Not each and every scenario a user wants can be achieved using settings. It is either unite or create. If you want a different behavior, choose the create option, then unite the solids that need to be melted together.

Roy Klein Gebbinck

@weedywhizz:
If may help if you post a dwg. But AFAIK a single solid cannot have faces that touch (reading 'between the lines' I think that is what you want to achieve).

Joe Dunfee

I think there is a bit of a bias against dis-jointed solids in the modeling world, because they cannot exist in the real world. Solids are always connected in the real world. So, even if a program permits dis-jointed solids, it is reasonable for them to always assume touching parts of a single solid should be melted together.

I suspect that a very slight offset is the only way to get what you want. But, you can make the offset even smaller, since geometry is stored in more decimal places than the 0.001 mm you specified.

If you specify for it to be offset by 0.000001 mm, you will probably not notice it because you will normally set your units to only display a few decimal places. So, any distance commands, or dimensions will not display that 0,000001 difference. Even if you don't see the value showing up on screen, BricsCAD will know they are not touching. This may have impact on other things that should touch or be parallel after snapping to one of those lines that are 0,000001 away from each other. So, there are liabilities with this approach that can be hard to predict, and will show themselves a year from now.

Perhaps if you are only wanting the visible line where your two solids are melting, you might simply draw a line there.

-Joe

weedywhizz

Thank you for explaining. Makes sense. Just recorgnized that when I create a junction in Sheetmetal it automatically adds a gap of 0.0011mm.
Lesson learned, thank you