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Press fit kit for laser cutter, test and research.

Assignments

Cut something on the vinylcutter
Design, lasercut, and document a parametric press-fit construction kit

Research¶

For this exercise, I started by searching and trying some simple forms. For that, I used fusion 360 which makes it possible to assemble components very easily. I used parameters to drive X, Y dimensions (set equal), thickness material and notches (set equal to the material thickness).

Then i looked for examples:

I explored the work done by Daniel Asprilla during fabacademy 2015. And i really likes his press fit lamp kit !
Another nice project of Mechanical Iris made by NNT
Geodesic dome

Geodesic dome press fit construction Kit¶

Wishing to work on frameworks to create “closed spaces”, I decided to create a geodesic dome. I was inspired by the Geodesic dome which is build only with 10 hexagons, 5 half-hexagons and 6 pentagons. The construction principle is simple and can be easily implemented with CAD software (I used Fusion 360):

create hexagons and pentagons whose edges are equal
assemble a pentagon with 6 hexes (one for each edge) taking the middle of the edges as reference and defining a revolute joint
continue on this principle until you obtain the desired number of facets

First test¶

PARTS
JOINTS

With this technic, the assembly of the parts would be difficult, and I couldn’t put all the connecters.

Final solution¶

Parameter definitions
Creation of parameters as on the plan

Assembly of hexagons and pentagons
Creation of pentagon and hexagon with equal edges
Assembly of the parts taking the middle of the edges as reference and defining a revolute joint
The second assembly blocks the parts together. (An angle of 41.8° is formed between the hexagons and 37.4° degrees between hexagons and pentagon)

Creation of 2 connecters, one for the 37,4° angles and one for the 41,8° angles
Creation of middle a plan (middle of the nicks) to create a new sketch
Projection of the nicks and edges on the new sketch
Creation of a middle line between the two projected edges
Creation of a circle coincident to the upper point of projected edges(!!the offset between circle center and the horizontal line is a parameter called “keythick” )
Creation of lines as on the plan
Extrude this sketch (distance=”thick”)
Creation of the parameters as on the plan

I reproduced the same technique for each of the 2 connecters (one between the hexagons and one between pentagons and hexagons)

Production¶

Parameters used¶

I used 3mm plywood to cut the parts with laser cutter and used this parameters

Machining file preparation¶

Creation of the drawing from the fusion 3D model (just to get the paths of the different parts)
Export from Fusion drawing module to a PDF file

PDF

Importation of the PDF file with Inkscape
Multiplication of the parts (duplicate tool “ctrl+D”)
- 15 hexagons : 15 parts
- 6 pentagons : 6 parts
- hexapentkey 37,4° : 30 parts
- hexakey 41,8° : 45 parts

SVG

Cutting parts¶

I used our 100W CO2 laser cutter. First i tried with a value of 0,5 mm for the blocker parameters (top of the picture) but it was too small to block the parts. I changed the value to 1mm (bottom of the picture):
The width of the kerf is proportional to the power used. The higher the power, the thicker the kerf. To cut plywood 3mm a power of 30% is enough (for our machine).I tried without offset (no compensation of the kerf) and that gave good result. The dimensions of the cut pieces made it possible to obtain a mounting that is both robust and easy to do.

Final result¶

Vinyl cutter¶

This week, for our reception area we had to create a display. I trained a colleague to use our vinyl cutter.

Our Fab Lab is equipped with a Cameo vinyl cutter

I made the design directly with the Silhouette Studio software software because it was only text
We didn’t need to compensate the kerf
Specifications :
- material: yellow vinyl Silhouette
- Blade high : 2
- Speed : 5
- Force: 10