Basic thoughts about laser cutting

[Thomas Marocke]

While building the CAF La Belle I noticed that all components too small because the laser always cuts on the drawing line. The lines are part of the component. The laser must cut outside the lines?


Arms for the pump levers in the laser board. And two self cut levers.


After cutting out of the board, the arms are clearly too small and the laser carbon is not yet removed.


The same is true for the levers. The left lever is cleaned, the right one still raw.


If I remove and clean these two parts, they are gone.

Granted, the components of the La Belle are very small. But they become even smaller when laser cut. Must the laser cuts be outside the lines on all lasercut kits, or am I wrong?

With best regards
Thomas

 

[Y.T.]

You are correct. It is the issue with laser tracing set up. It had to be adjusted to cut a bit out of line centre.

 

[Uwek]

I think this problem is mainly in the older kits with laser cut timber sheets.
And the La Belle is one of the older POF kits.....
in the meantime f.e. @CAFmodel is doing the design much better and is taking this problem into account.
In addition the manufacturer are now using also finer laser, so that the effect is getting much smaller

 

[paulv1958]

Any laser cutting must allow for the kerf or laser burn thickness. A thick cut is normally caused by the laser not being focused optimally.
Unlike CNC where you can specify the cut to be on, inside or outside the cut lines, a laser is always on the line as it only knows one positioning point, the cut line.

To ensure the correct cut size the object must be increased in size to allow for the burn wastage. Most modern software will take the laser cut width( kerf ) into account and add it to the overall size. However you need you know the beam width for the machine. This has to be calculated and the software told the width. If not then the part will be smaller. Most quality lasers provide the beam width as an approximation and this can be added to the software settings. However like CNC parts as the laser tube begins to wear or exact focus is not set, then it can vary.

Its like any cut with a saw, the blade width has to be taken into account.

 

[Dave Stevens (Lumberyard)]

i have been creating laser cutting files and working with laser cutters for years.

the laser does indeed have a kerf (width if the beam) the laser i am using now is .012 thousandths so when i finish drawing a part i will offset the lines .012 + .006 for a total of .018 which will take into account the kurf plus a little extra to clean the part. The parts you are showing in post #1 is a poor job of laying out parts.
When you have something like a scarf where 2 parts come together you will be .024 off and parts will not fit right.

looking at this cutting file


when you zoom in close the black line is the keel part the red line is the laser path so the edge of the beam is just shy of the edge of the part