Layers & 2d

[oldnewt]

Hi all- In trying to work from a 2d file - I have tried to use layers to trace over the 2d image - but I still get error messages that "operation has caused drawing to merge with existing graphic? Any ideas? Thank You. oldnewt

[TIG]

Layers do NOT separate geometry [unlike in CAD], all that SUp layers do is control objects' visibility.
All of you 'raw' geometry should be made on Layer0.
By making/moving geometry inside groups or component-instances you separate the geometry from other geometry that might otherwise stick to it.
You then control visibility of the groups/instances using layers of those.
You cannot separate some geometry by simply moving it onto an invisible layer as any new geometry you add within the same context will still merge with it.
You are best advised to always have LAyer0 set as your current-layer.
For example draw a rectangular face on the current-layer [Layer0].
Select the face [not its edges] and change it to be on another layer [say Layer1] that's switched off.
You can no longer see it.
Now erase one of the rectangle's edges.
Switch the Layer1 and the face has gone too, that's because although you had [inadvisably] moved the face onto a hidden layer it was still connected to its edges on Layer0 and therefore was erased when an edge went.
No try this...
Draw another rectangular face on the current-layer [Layer0].
Select the face and Group it.
Draw another rectangular face on the current-layer [Layer0] exactly over the group.
Erase the face but leave the edges.
Now select the group and move it onto Layer1 and switch that layer off.
You are left with the unfaced edges.
Erase and edge.
Switch Layer1 back on and the face reappears.
This is because you have separated some of you geometry using groups and changed visibility of the group's layer.

So if you want to trace over something make sure you are working over a group/instance and then only the geometry in the current working context will interact