working with imported DXF/DWG

[moyesboy]

I am often working with an imported DXF/DWG which tends to be a fairly complex representation of a PCB.
I import the DXF/DWG as a 2D sketch into my new part, and then create new sketches on the same plane is the imported sketch to represent the stuff I need for the mechanical design.

Unfortunately I often find the imported info is not scaled correctly (inches-mm) or is displaced from the origin (cheap an nasty PCB software elsewhere in the company).
Its a lot of work to reduce the complexity of the dxf in dwg editor to include only what I need, as I don't always know for sure what I need or what I don't need. I prefer to have the full dxf data in my imported sketch. However even the slightest manipulation of the imported dxf is impossible - its just too complex for SW to do anything with. I just tried to scale the sketch I just imported and its still not done it after 20 mins (and my machine is no slouch, XP64, i5750, 8Gb of ram etc).
Am I doing this in the wrong way somehow? Why is solidworks so incapable of handling the imported dxf data? you are supposed to be able to work with quite complex imported sketches for 2d-3dtranslation. If its like this that must be another solidworks "pretend function"!

 

[macduff]

Oh.............my friend..........I deal this constant battle almost everyday. SW sucks for handling dxf files for PCB's boards, and the drawing files are enormous in file size.

Some things that might help:
1) try cleaning (dxf) as much as you can in DWGeditor
2) make a block in DWGeditor and then insert in a SW drawing

That's as much as I can help for now.

Hope this helps,

Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2009 SP 4.1
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer

 

[moyesboy]

I really really wish I could directly import gerbers, as its because the data is exported to dxf that I end up with suxch a dirty dxf - the gerbers must be relatively clean becuase the tracks and board outlines work well enough in production.

Is it not possible to end up with a separate 2D sketch on the same plane for each dxf layer? (and thus several simpler sketches) I actually thought it did that but it doesn't seem to be possible, at least not in one operation.

I was wondering if there was some trick by importing it into a drawing rather than a part and then generating the part from the drawing or something?

 

[macduff]

I do not import exported dxf's into SW parts or assemblies. I take the top and bottom views of the dxf's and use them in a SW drawing only. That's why I recommended in my above statement.

Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2009 SP 4.1
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer

 

[ctopher]

IMO, it's worth taking the time to create the models from scratch than to deal with 'junk' from imported DXF/DWG files.

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[MadMango]

I use DWGeditor and turn off most of the layers in the DXF. I leave the board outline and drill holes active and cut & paste that as my first sketch, and extrude that to get a basic PCB.

Then I go back to DWGeditor and turn off the drill holes, and turn on the pad or mask layer, again cut & pasting and inserting into my basic PCB and extrude them .001" to have the pads in the model.

Silkscreams... I mean silkscreens are the worst. I turn off all layers except for the silkscreen layer (for that side of the board) and cut & paste that for reference into my model. A lot of times I have to manually sketch all the areas that need to printed since the import is nothing buch a bunch of lines that never converge at the corners, and radii or circles are a bunch of faceted segments. These I extrude .001" so they show up in the model.

For silkscreened text I use Tools>Sketch Entities>Text to create my text, then Tools>Sketch Tools>Modify if I need to rotate text 90degs or just position them. This is also extruded .001".

The fun starts when you have to do the other side of the board, as the DXFs I get are useless, and I have to flip them around and mirror.

THEN I get to start on populating the PCB with components. Luckily I'll get a complete BOM from the EEs and they haven't specified any new or custom components and I can simply pull in components from the library I already have. After placing them, I have to rename them since the EEs never seems to try to use standarized values, which requires creating new P/Ns in our system. I then search Digikey and 3D ContentCentral looking for things I need to add to my library, or I download datasheets so I can model something new.

After both sides of teh PCB are modeled, I'll create 2 folders in the FM, one for Front Components and one for Back Components. It just helps to get rid of some of the clutter in the FM.

I love modeling PCBs.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[moyesboy]

I prefer to take the original data and work with that, as then there will be no accidental error.
I just need to manipulate the dxf a bit so I get it coming in at the origin and at the correct size, accepting that the sketch cannot be manipulated in solidworks.

There doesn't seem to be a problem having the complex sketch dormant in the resulting 3D part, as long as it is used only to size the sketches I extrude - or to locate componets in a PCB assembly.

 

[moyesboy]

Madmongo, if you import the whole DXF as a single sketch, its not too bad provided you do not manipulate it in any way. It doesn't seem to eat the system resouce unless the sketch is opened for edit.
I open the dxf in autocad/dwg editor, scale it if necessary, move it to the origin.
Then import or copy paste that whole dxf into a single 2D sketch in my model.
Then I can add the geometry as a separate sketch to extrude, and mate componments to the dxf sketch lines. I only place the relevant components, large ones for space envelope, connectors etc.
On the finished part the dxf can be switched on or off - and you can extrude any pads needed quickly by sketching or converting the dxf geometry onto a new sketch.

Seeems, unfortunately, I might already be close to the most time efficiant way of getting what I want
I must just guard against being tempted to edit the complex dxf sketch as that just locks up the machine and I have to crash out of SW losing anything I haven't saved! I wonder if its possible to lock a sketch an make it so it can't be opened...

My PCB guys can produce idf files, but unfortunately they don't model the pcb outline correctly (unless its a simple rectangle) or generate the components consistently. So its no use at all - though it did get me excited at first!

 

[FreddyB]

This is ridiculous. Your problem is not unique to you as I have in fact suffered it before myself, and I am sure many others do or have too. The difference is that having decided what a complete waste of time it all is and further that potential remains for errors to impact the overall design, I did something more basic about it. You have admitted that the PCB software is cheap and nasty. That is where the problem lies. I don't know what sort of company you work for and who deals with providing engineers with the tools with which they do their job, but you need to put forward a case for change. There are some quite inexpensive PCB software tools out there that provide better export facilities i.e. IDF. If you have Circuit works you can import a nice 3D model of the board. In the work I do I would find it very difficult to work without.

Have you tried getting someone to reassess the company needs in this area to ultimately save money?

 

[moyesboy]

Well Freddy, it must be great to have an influential position and work in an ideal world!

When it says on the box with the PCB software in it that it produces a 3D IDF export, but it doesn't produce one thats valid...then I know I'm not in your ideal world but my real world

Fortunately, provided I don't make the mistake of trying to edit the complex 2D sketch itself, the way I'm working is accurate and not too time consuming.