week 3

press-fit construction kit designing

For this week project i want to do a foldable space saving chair. to make it i will use multiple layers of mdf joint by a living henge part that will let us make the chair like an accordion so when the chair is open we will keep it open by adding press-fit separators.

to design the chair i will vectorize the shape op a chair and then edit it to add the living henge part and the space for the press-fit separators.

i will use parametric design to do the chair scalable keeping the same size of the lines that will fit the mdf width so i will first cut a little chair to test if it works as i want saving some material and then if it works scale it to a real size chair.

to vectorize the chair shape first i have to add a new layer in auto cad to draw the shape over the image of the chair.

then in the layer properties i will turn off the picture layer to add the pressfit cuts in the draw layer.

to assign the same parameter to a desired section in the draw we use the lineal restriction tool and we select the section clicking in the first and final points of the line showed by autocad in red that will open a text box showing the actual value of the line size.

to have the same size in that parameter we have to change the parameter value to the user parameter created, we must type ="name of the user parameter" in this case i call it mdf_width because i want that all the cuts could be modify to fit the width of the material

then i use the coincidence parametric tool to fix the ends of lines and arcs. now we can modify the draw to the different widths of mdf and it will keep all the draw joined, to do it we click on the tool, then we select the points that we will join.

To scale the draw proportionally i will create the user parameter named "Xscale" that will have the scale factor so we can multiply all the values by the xscale factor that we select.

as we saw in the pictures the draw scale proportionally but the spaces for the press-fit kept the size selected in the user parameters. to do the right parametrization i took the original size as start point, i add parameters for all the measures involved in the draw like radius and length and i multiply the actual value times the scale, so for every measure i had the next formula "orinal size * scale" this is an example of a formula used in a radius.

to join all the layers i will assemble rectangular pieces of mdf. in the middle part of the living henge we can find squares that will receive the pieces joining to layers by the living henge. we have to join two layers together by the body of the chair, as we did with the rectangular pieces in the living henge before, we have to assemble the rectangular pieces to join the layers.

here we can see the 4 separators, the 4 layers of mdf and the rectangular pieces that will join the chair.

finally we have a file with all the drawings needed to do a mdf chair, in the file we can modify the width of the material, the scale of the chair and the separation of the layers when the chair is open. we have to edit the separator to the final number of layers that we want, the position of the living henge we could do these changes easily thanks to our parametric design.

you can download the autocad file clicking here

Vinyl cut sticker

to vectorize the image i will use illustrator

After it trace and expand the image i will change the fill to none to get only the lines that i need to cut

this is the curio machine that i use

when all is set i cut the vinyl, put some transfer paper, i stick the vinyl in the clean laptop, i pass a card to eliminate the bubbles and finally i peel the transfer paper off

you can download the image file clicking here

finally one of the important things is know what is the width of the laser beam. having that measure we know how many material is going to be burn by the laser in every cut to measure it i´m going to use the ten rectangles that i draw and i´m going to take measures of the space burned between every rectangle and the space left. here i will show some pictures of how i did it.

as we saw in the pictures the rectangular space was measure in 30 mm, in the little rectangles the final length was 28.7mm so we lost 2mm approximate in burned material, it were 11 cuts so we will divide 2mm between the 11 cuts to find the laser width . 2/11=0.1818181818181818 if we do the approximation we can say that our laser beam measures 0.2mm.

the parameters that i use to cut in the laser machine were the sown in the image below

the software is smart carve and the layer that i used was the blue so for cutting 3mm mdf i choose 75% for he max power 70% for the min power and 23 for the speed this configurations have been selected thanks to previous test cutting the 3mm mdf.

design, make, and document a parametric press-fit construction kit desing and make a vinyl sticker

to do the press-fit construction kit i will use auto-cad.

First i had to search and download the image in black and white. then i open the image in illustrator

week three

Computer-controlled cutting

the chair will be closed by putting all the layers side by side saving almost the 50% of width while it is not in use. it will be open separating all the layers of the chair using the separator that will join each layer of mdf in the press-fit cuts. for the test i will cut 4 layers, but the chair could be as long as we wanted just by adding more mdf layers and editing the separators.

this is how it look the final chair assembled and an example of how many space it saves.

i run the curio software, import the .dxf file and set the size and machine parameters

to do the parametric design in autocad we have to click on the parametric tab showed in the screenshot in number 1 then click on the parameters manager icon showed in 2 click on create new user parameter showed in 3 finally give a name to the new user parameter and change the units value to the size wanted in the expresion section next to the name sowed in 4

now that i have the correct shape of the chair i only have to add the living henge to give each layer of mdf the flexibility to make the chair like an accordion.

or the .rar file with the .dxf extension file inside clicking here

then i clicked on the image, then object menu, next in image trace and finally in create an expand

After i get only the lines i click on file, then export menu and finally export as, so i can save the archive to the .dxf extension that is the kind of file that the vinyl cutting machine curio recognizes.

and the .rar file with the .dxf extension file inside clicking here

Carlos Pérez Ramírez