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Alibre Design and DXF Blocks

Many DXF files use blocks.  A blocks defines an object, which then be placed in many locations, and each location can be scaled and rotated individually.   For example, the standard Eagle PCB DXF export ULP uses one block for each different style of pad (circular, square, etc), and then scales, rotates, and places these blocks for each individual pad.

But blocks aren’t so great when you’re importing them into Alibre Design (AD).  I’ll look at a few issues by trying to extrude the Phoenix ZFK3DS 1,5-5,08 (1704415) terminal block outline; for example, I might want to model a cover for the end block (1704554).  The files are available in a ZIP archive here Alibre and DXF Blocks.zip.

The DXF file provided by Phoenix uses blocks for all the views.  I removed the views I didn’t want; the resulting file is Phoenix 1704415 Profile – block.DXF, shown below in DoubleCAD XT.  You can see the blocks on the right.

Phoenx 1704415 Profile using blocks

Phoenix 1704415 Profile using blocks

I can’t extrude that profile; I need to remove the pins and the pegs.  But I can’t edit the block in the drawing (left side of screen).  In the Alibre sketch mode, I can only move it, delete it, or copy it.   In the DoubleCAD drawing I can only scale, rotate, move, copy, or delete the block.

But I can edit the block in DoubleCAD by selecting the block in the block tab (shown on the right), and pressing the EC (Edit Content) button.  The block is now displayed in the drawing area, and I can edit it, then press the check mark (next to EC) when I am done.  The final result is shown below and in the Phoenix 1704415 Profile – block for Extrude.dxf file.  Note that when you edit a block, all objects based on that block will update when you finish editing.

Phoenix 1704415 Profile - using blocks, edited

Phoenix 1704415 Profile - using blocks, edited

Another approach is to change to a no-block approach by editing the block you want, selecting everything, copying it, closing the block editor, pasting the copied part into the main drawing, and finally deleting all the blocks in the block tab (when you delete a block, all the objects based on that block are deleted).  The result is in the Phoenix 1704415 Profile – No Block.dxf file.

With the no-block file, you can delete the stuff you don’t want in either DoubleCAD or import it into Alibre Design and delete it in AD’s sketch editor.  The no-block approach isn’t good for a circuit board full of blocks, but it works great for a single profile.

There are some other differences between the block and no-block approaches in Alibre Design.  Alibre has a non-obvious approach to pasting in sketches: “normal” pasting (Ctrl-V) always pastes the clipboard content in the same position relative to the origin; paste stamping (Ctrl-T) lets you place it where you want (press ESC when you’re done pasting).

The approach is always the same for getting a DXF file into a sketch: import (which opens an Alibre drawing), open sketch mode, select everything, and then paste it (Ctrl-T or Ctrl-V) into the desired sketch.

So far I’ve found that blocks don’t paste correctly; they get pasted with some sort of an offset, whether using paste or the paste stamper.  Non-block DXF drawings paste correctly.   But it’s easier to move blocks in Alibre sketches: just select them and drag.  To move a non-block figure, you have to select all of it, cut it (Ctrl-X), paste stamp it (Ctrl-T), move it where you want, and then quit stamping (Esc).

Here’s a picture of the finished profile extruded in Alibre:

Extruded DXF profile

Extruded DXF profile

I’ve used DoubleCAD XT for all my DXF manipulations because it’s free and it works for me.  You should be able to do the same things with any other high quality AutoCAD clone.  DraftSight is another free AutoCAD clone worth checking out; it’s available on Windows, Mac, and (real soon now) Linux.

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