Computer-Controlled Machining

When Imagining a project I imagined a chair that can be put in a park but later also found out It can be used in FabLab Inorder to keep some seats that are not movable and to also be used as a place to sleep at night.

I uploaded the files from Solidworks, saved as DWG so that Vcarve a software used by shopbot may understand the model that i designed in solidworks.

Assembled Design in solidworks 1 support part another part of leaning on parts in form of chairs I printed 3 of them flat sitting part

Then I had to save them in .DXF files because VCarve software that works with the shopbot only supports 2D Files it means .DWG or .DXF files

.DXF files that I was going to import in VCArve .DXF files imported(dragged and dropped) in Vcarve and arranged to fit on the sheet,one sheet Sheet size(height,width) can be seen on the left Profile Setting Machine settings After setting the profile and calculating it Opening the ShopBot controller Fixing the sheet As the sheet looks soft,I had to fix the screws in many parts Our shopBot has an already set X,Y position so what you have to do is set Z,and our tool that helps in setting Z is broken so we do it manually and being careful So the shopbot began cutting Shopbot done cutting After assembling I asked my friends to sit on it so i can document
Mistakes made

The mistake I made was that I did not use dogbones and that made use the sanding method

How do dogbones work

When cutting materials with the CNC, a known problem is that while the CNC can make a perfect outer corner, the inner corners can never be more sharp than the diameter of the cutting tool. So if you are e.g. using a 6mm mill, all the inside corners will not be perfect right angles, but will instead have an inside diameter of 3 mm (half the cutting tool's diameter) Sometimes these small rounded corners don't matter, but they are almost always an issue with joints - where often another piece of plywood, which by nature is square, must fit precisely in a hole or slot. If the hole or slot has very rounded corners, the mating piece just isn't going to fit in.

An example is the above finger box, lots of joints with inside corners that have to be square, not round. There is a solution to this, called dogbones. You can see why they are called this below. Many people (and software) make very obvious dogbones, but it is in fact (with a 3 mm mill) possible to make almost invisible dogbones.

Here is how dogbones are and how they prevent the sanding problem and make the parts fit

While cutting the upper parts pockets couldn't perfectly meet so I had to sand with a sanding paper and used holds to hold it back