A novice at work is a dangerous thing! But still I try to progress my model and then run up against a problem

In the attached SW2013 file is a part I am trying to recreate from a 2D dxf import. I have attached the dxf file as well.

When I imported the dxf it became Sketch 1 and then when I tried to extrude it to 0.33mm thick it complained about open contours.

Unable to find the contour it was moaining about I moved on to Plan B

Plan B, in half remembered thing I was told by someone a few days ago was to start a new sketch and trace over the original and then extrude the new sketch.

This appeared to work but you could see the first sketch as a sort greyed outline behind the body of the extrusion

Simple I think. Delete Sketch 1, after all i did was trace over it.

But no, there is some sort of link and SW has another, rolls back the feature tree and produces this error message

You'd think with an error message like that I'd soon have it fixed and be on my way, but no, I am stuck, the above doesnt't mean enough to me to be of any use. I can't see any dangling bits or fancy colours or any missing geometry.

Could one or more of you kind people out there help me : -

• Understand the problem with the original sketch 1 and explain how I find and deal with the problem so that I can sort myself out in future and don't need to go on to the sketch 2 version and
• Explain to me what the problem is with the sketch 2 approach, what I have done wrong and how I avoid it in the future

If yo explain it to me like you are talking to a complete dimwit you'll be aiming at about the right level!

Just in case you are wondering why I have ended up where I am here's the story. The parts are for the cab of a scale model train and are to be laser cut from wood. They were created by scanning an image in a book and then importing this scan onto a layer in CorelDraw. Having messed with the image to get the right scale the parts to be cut were traced in another layer and the file prepared for cutting. The laser is hooked on the end of CorelDraw - it sees it like a print driver - and ordinarily that would be it, job done no proper CAD, 2D or 3D involved. Then I decided to see if it would assemble so saved the parts from CorelDraw as dxf files to import them in to SW, make them into 3D parts (the 3rd D is the material thickness 0.33mm) and then try to put the cab together. The ends and floor all imported without problem. The sides with the fancy curves on the back edge are having this problem.

I will be eternally grateful for any help

Paul Martin