# Make Education Forum 2023 Presentation: Avoiding scorch using two sided laser cutting.

The first 3 puzzle pieces are cut from one side using the low speed and a high power needed to cut through 1/4″ plywood.  The black scorch has to be sanded or wiped away adding significantly to post laser treatments.    One approach if your laser is not cutting through is to run a second pass.  This results in more char.  If we can cut from both sides we can use the settings for wood that is 1/2 the thickness. So we can use 1/8″ settings for 1/4″ inch wood and 1/4″ settings for 1/2″ wood.

Jordan Varat created a document with instructions.

At the conference, we shared two projects that need thicker wood:  the classic circle area model and the Heart-Square-Circle.

For the classic circle model, you simply cut a circle into pie pieces, in this case 12 of them.  One of the purposes of the model is to show that the circle can rearrange to an approximation of a rectangle.  Setting up the pieces in a circle is the wrong choice, the center becomes severely scorched regardless of settings.  We can however also set up the pieces in the rectangle and cut from that figure.

With Bass wood which is less dense than baltic birch, we decided to see if we could succeed with 1/2″ thick wood.  We tried a simpler circle square heart model for the demo at the conference.

The steps to get from the image for the front of the wood to the image to print on the back are the same each time.  You flip your materials in the same way:

Both the circle area model and the Heart square circle are models that can be made easily in any CAD program, but their mathematics are very compelling.  They are great first math projects, except both need 1/2 inch wide wood because we need the 1/2″ gaffer tape to make the hinge.  By creating a design and adding 45 degrees, flipping the image vertically and subtracting the 45 degrees, we “flip” the image on the diagonal.  Using this technique means we only need one 90 degree angle in our material to orient our image on both sides, we can cut wood twice as thick with the lower power setting.

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