Assignment 08_computer-controlled machining

01 test runout, alignment, speeds, feeds, and toolpaths for your machine (group).

02 make something big

01 test runout, alignment, speeds, feeds, and toolpaths for your machine (group)

The Router CNC we have in Fab Lab Santiago is a BUCA; it has a half bed size (1400X1100mm). For this assignment, we search which materials we had to use the machine, and we found a lot of MDF, plywood, OBS and pinewood. Because of the size of our router, we have to adequate our files to the dimensions of the machine.

Kaleb and I work in Fab Lab Santiago, he since a year ago and I had been working here three years. So we both have a lot of experience cutting different type of materials and setting our router CNC. So we both gather some images of previous works we had done. Here some photos:

For the assignment, we made some test to refresh our knowledge. First, we generate some files to test the alignment, speeds, feeds and toolpaths. Also, we seize the group assignment to prototype one of the part of Kaleb’s chair.

Screenshots of the file:

We set up the plywood and test the file first in the air just to be sure it worked fine. Then we try different speeds and feeds for the prototype.

Also, set up the origin, checked the toolpath and speeds. We are using a 7.9mm end mill because we feel one of the best mills to cut large formats in plywood.

This is how the machining went, pretty smooth.

The test we did worked fine, the prototype fits perfectly, and now we are ready to work on our furniture.

02 make something big

This kind of router CNC has a sacrificial bed of 30 mm MDF. To fix the materials you want to cut, you just screw them to the bed. Ideally, you should have a screw in each corner of the material, but if it is not straight, you must add the necessary screws so that it is horizontal. In this way, when the strawberry will cut homogeneously through the wood.

Once you have fixed the material, you must change the strawberry for which you are going to occupy. This depends on whether you want to cut or model. In this case, the straight cutter is ideal because we are only going to cut.

To set the file, ArtCam is used in Fab Lab Santiago. In this software, the cutting and modelling trajectories are determined, customizing:

Depth of cut
Type of trajectory (external, internal, by the vector or scrabble).
The end mill, its cutting speed (is predetermined by the type of end mill) and its steps.
The thickness of the material.

Once all the parameters are set, the trajectories are saved in a TAP file, which is the one that is imported in MATCH3, software from which the machine is controlled.

In Match3 you can set the origin of the file for fabrication, the most traditional way to do it is setting the origin in the inferior left corner of the material, the z-axis is just in the top of the material.

I decided to design a piece of furniture that would help to order different elements in the fab lab and be adaptable to different needs: folders, tools, samples, etc.

The idea of the design is that it can be used against the wall or as a separator of environments, allowing to adapt its modules.

The material that I used was OSB of 11,5 mm. To work with OSB it was necessary to constantly measure the thickness of the material since not all the plates had the same thickness. I use a 6 mm flat end mill to fabricate the furniture.

Since I was working with OSB, and it is an adaptable material in case the assemblies are very just in size, I decided to leave little kerf since I could force them to assemble, which was better than more loose.

I add to the sketch some dog bones to the internal angles because I need to assemble perfectñy the pieces. If I don't add them, the angles will be rounded, because the end mill is circular.