Problems with lasercutting

[whistler]

Hi guys!

New to this forum.

I´m having some trouble when getting some parts lasercut.

The company says that the machine stutters and makes a mess when it tries to cut my parts. They say that the holes in my parts are made up of many small lines and that he has tried to make them in to one line but have failed.

Any ideas?

I export in dxf when sending him the drawings, if it matters.

Cheers
Daniel

[Mike 1948]

Hi guys!

New to this forum.

I´m having some trouble when getting some parts lasercut.

The company says that the machine stutters and makes a mess when it tries to cut my parts. They say that the holes in my parts are made up of many small lines and that he has tried to make them in to one line but have failed.

Any ideas?

I export in dxf when sending him the drawings, if it matters.

Cheers
Daniel

In tools, options, Performance, make sure your resolution is set to the max. Also when doing Save as, look at bottom right corner, options, set to arcs or spines, I believe. One of those options will get rid of the individual straight line segments. I'm not at the office but will verify in the AM. I have no problems with plasma cutting dxf files.

Mike

[fatal-exception]

The only place I've seen this to be a problem is when flattening plates made with sheet metal lofted bends. If you cut holes in the un-flattened loft, then flatten the plate, the holes do not come out as circles.

Like Mike said, I have no problem plasma cutting dxf's from Solidworks, whether it be an extruded plate, or a flattened sheet metal part.

Paul

[Beighs]

This sounds like a problem i had exporting dxf's from ProE drawings. Check the dxf export settings, it could be because you have it set to splines or polylines.

[whistler]

Thanks for your replys guys

The export was set to splines, so I´m changing to polylines instead, the only other option there was. I also added merge endpoints.

What do you think of that? Could it work? I have not sent it to the cutters yet.

Cheers
Daniel

[ger21]

If you post a sample here, we can look at it and see.

[whistler]

Here is the file.

Thank you

[ger21]

The round holes are circles, so you should be good there. There are some elliptical arcs though, not sure if they'll have trouble with those or not.

[oldhaitianrat]

Hey Daniel
I've had "laser control issues" with customers' files like this as well.
I just pulled your .dxf and took a look. The holes appear to be fine, but the "teeth" of the monkey are probably where your vendor's laser's motion control is having an issue. The "teeth" appear to be created using both splines and tangent arcs. The software used to create the G-code for the laser's CNC control will usually translate a spline as a series of tiny lines (even as short as .002"). As you can imagine, this creates a huge quantity of lines in the part program. This will cause the CNC control to "stutter" as it tries to navigate through the code that probably could have been easily represented by 3 or 4 tangent arcs (per spline section). I'm not sure you can change your export parameters in SolidWorks for a file like this to give you any better result(s). Your BEST remedy would be to create the original CAD data using a series of lines and tangent arcs rather than splines (although art often demands the use of splines).
I've attached the .dxf export of my laser's CNC code so that you can see the issue with the "teeth". I may even try to cut one for you just because I'm curious.
I hope this gives you a little insight into your vendor's issue. I think they are shooting you straight!

Have a good one!

Loren
www.briscoinc.com

[whistler]

Hm.

Could it be the ellipse tool that has created the splines? The teeth and also, if I´m not mistaken, the nostrils are partly made with ellipses.

Everything else is made of lines, circles and the fillet tool.

I shouldn´t have a problem replacing the ellipses if that is the case.

Thanks
Daniel

[oldhaitianrat]

Daniel,
Yes! - I do believe that's the problem. My experience is that an ellipse is to CNC G-Code as Kryptonite is to Superman. It may not be deadly, but it sure won't yield a good result. Any time you are designing a part which is to be manufactured using some sort of CNC control try to stay away from ellipses, splines, parabolas - anything that can't be easily (and concisely) described as a series of lines and tangent arcs.
See you later!
Loren

[whistler]

Super!

Thanks guys! Appreciate the help.

Now I will redo the skull and send it again to the cutters.

Just as a side question, when you cut out letters from sheetmetal, will solidworks automatically do it in a way that the lasercutter can handle or will there be splines involved?

Cheers mates!