Inkscape how to make a pressfit design

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Example of a press fit design: instructables


Understanding the laser cutter

The lasercutter cuts by burning away a little bit of the material. The laser follows the center of your vector line (drawing) and will burn away 0.1 mm of material on each side of the vector. Beware! Different materials and different heat settings can influence how much material exactly is lost. It is recommended to first test joinery designs before cutting the whole sheet.

Laser-cutting-example.jpg


The burning away 0.2 mm of material is a guideline, not a golden rule.



Inkscape example: sizes

Here you see a box drawn with the size of 50 mm by 50 mm.

Laser-cutting-example 2.jpg

But after cutting out this cube with the laser cutter, the actual size would be 49.8 mm by 49.8 mm as the laser will remove 0.1 mm from all sides.


Stroke vs. Fill

Open up the menu by going to object > fill and stroke.

In this menu you can change the fill (color) and the line thickness of your object. If you want to design something where scale matters (like with press fit) it is recommended to draw with a "fill" only. Because the line thickness is added to the size of your object.


Example stroke vs. fill

Draw a box of 50 by 50 mm, but also set a line width to 2 mm. (object > fill and stroke)

Now if you look at the object with the box tool, it still seems to look ok, because that tool measures from vector to vector.

Laser-cutting-example 3.jpg


But if you use the black mouse tool to select your object, you can see that the line width is actually gets included in the size of your box. The line width of 2 mm get's added from the center of your vector. Hence actual size of you box is 52 x 52 mm.

Laser-cutting-example 4.jpg



inkscape ː how to make a test shape for lasercut pressfit

Let's say we want to make something like in this image, having 2 pieces with a slot, that (press) fit together.

Cardbord-pressfit-test.jpg


1. Create a large box (50 x 50 mm)

Laser-cutting-example 2.jpg


2. Measure you plate of material.

Measure your material.JPG

The MDF you see in the photo is a standard plate of 4 mm thick, but if you measure it you can see that it's actually 4,13 mm.


3. Create a smaller box that overlaps the first, and give it a width of your measured plate.

1 inkscape-how-to-make-press-fit.jpg


4. If the smaller box is behind the bigger box you can let them switch places by selecting the shape you want to move to the front, and go to Object > Raise to Top

2 inkscape-how-to-make-press-fit.jpg


5. To get the smaller box nicely centered. Go to Object > Align and Distribute.

Select both shapes, then choose in the Align and Distribute menu 'biggest object' and click on 'center on vertical axis' button.

3 inkscape-how-to-make-press-fit.jpg


6. To subtract the blue box from the red one, select both shapes. Go to Path > Difference.

4 inkscape-how-to-make-press-fit.jpg


Now you design is ready, final step is to prepare it for the laser cutter.


inkscape ː how to offset trick

7. Select your design and and go to Object > Fill and stroke

5 inkscape-how-to-make-press-fit.jpg


8. Go to the stroke paint tab and set a color. (click on the box)


9. Then go to the stroke style tab and change the line width to 0.2 mm

6 inkscape-how-to-make-press-fit.jpg


10. (While your object is still selected) in the menu choose Path > Stroke to path


11. (While your object is still selected) next select Path > break apart.

Your object should now have adopted the color from your stroked line (in my case blue), and (if you zoom in) you should see 2 dotted lines around your object.

7 inkscape-how-to-make-press-fit.jpg


12. (While your object is still selected) go to the fill tab of the fill and stroke menu. And turn off the fill by clicking on the X.

8 inkscape-how-to-make-press-fit.jpg


13. Then set the stroke again in the stroke paint tab. (click on the box).


14. Back to the stroke style tab and set the line width to 0.01 mm

9 inkscape-how-to-make-press-fit.jpg


15 You double line is still one object. Go to menu > path > break apart to separte the two lines.


16. Deselect everything by clicking outside your shape (no more dotted lines)


17. Now select the innermost line of you object and delete that line (right mouse button).

10 inkscape-how-to-make-press-fit.jpg


Beware. If you design has a hole in it, then you should offset that line to the inside. Steps are the same but delete the outside line then instead.


18. Now the laser cutted shape should fit together nicely.

Example of press fit project