Week Eight

Computer controlled machining

Feb 22, 2018by Brandon Hanson
phase one : Design

As the assignments requires that to make (design+mill+assemble) something big (~meter-scale) extra credit: don't use fasteners or glue extra credit: include curved surfaces in this week i had so many ideas that i wish to make but finally i choose to make a parametric organic shaped table that i named upon the parameter coccon , that means "a fairly straight forward implementation of the Marching Cubes algorithm for turning iso-surfaces into polygonal meshes" as descriped here

so here are the steps i designed the script as i followed this tutorial here

but before i started I studied MetaBalls In computer graphics; which are "Are organic-looking n-dimensional iso-surfaces, characterised by their ability to meld together when in close proximity to create single, contiguous objects." Wikipedia where i downloaded the plugin in grasshopper and start testing therfore.

step one was to drop a componants that allows me to start the required desgin , the first one was (POP2D) this componant is responsible for the scadderingg simple points with a difentsion i have added a count and a seed which is the Random seeds to scatter them rapaidly , the other coponant is (pointcharge) this copmonant connects with the pop2D output as a point to give each oon of the points a strength, Ihave added the rquired inputs which are the point , radius and the point strength then was the last componant which is the cocoon to wrap the charg points with a bubble made of muiltiple cubes that where generated to volume around the populated points. using the slider i was able to calculate a preferred shape the next step was to move the the shape from grasshopper and turn it into a 3d shape using the baking option that allows to freeze the shape into an 3d file . then i used the 3d file and insert it into a software called Slicer so it will slice the shape into a press fit slices that can be put in a cnc router softwares as a 2d cuttingg file to create the 3d shape using slices later on. so the slicer software : first of all i have made a customized sheet size known for the program as my real life wood sheet size . then i have resize the 3d shape into smaller one so it will fit inside one sheet. playing around with the settings this was my final iteration look like.

via GIPHY

and then saved it as dxf
Phase two: Milling software
our cnc machine is ShopBot and we used the Vcarve PRO software to prepare the cuts. according to my design there it will need to cut in a multiple jobs. But before that i have checked our machine.that has a bed of size 96"x 48". It has the follwoing parts. Also we use a software called ShopBot 3 to control the machine.like we can set the zeros for the x,y and z axes. by moving the arrowa till the spindle is right where we want it as a zero to start from. for the z axis there is a matal plate to put under the spindle, and the machine knows the z automatically by slowly lowering the spindle until there is a short circuit while touching it. 00000000000000000000000000000000000000000000000

next i need to go back to the v carve Siftware to set up a file to be cut. opend the dxf file that where set up using the silcer software, as i have informed the other software the sheet sze i have found it perfectrilty fit in this software as i opened it. but adding the thickness of the wood plate and the dimensions of it. After that i have First started with the naming and labeling on every part. which i have made them separate cutting job to be done as engraving 00000000000000000000000000000000000000000000000

The number of passes is how many times will the tool go through the part to finish the cut. Since it is only a engraving, I chose a00000000000000000000000

I set the spindle speed to 18000 RPM and the feed rate to 2.7 inch/sec. The drill bit I chose was 1/4" because my design has a little bit of details in it

The next job the second and the last job was to cut the out-lines I chose to cut, so I chose the cut depth to be 17.3mm as my wood sheet is 17.3mm. I also added tabs. which are the parts the machine will stop and hold the cut on them so it would hold your part in place and avoid any breaking throught the cuting pieces as if it was loose and the spindle pass on it. for this job i have also set the spindle speed to 18000 RPM and the feed rate to 2.7 inch/sec. The drill bit I chose was 1/4" [img][/img]

creating a toolpath for the two jobs i can now see the simulation of each job and I saved them as sbp which is the shopBot format. With the help of my coleague Ismael , we set up the plywood board on the shopBot and set the zero for the z-axis. Next, I opened the shopbot 3 program and loaded the first job which is the engrave. then Switch the key to start warming the machine up, that usually takes couple of minutes. the machine while cutting then with help i removed all the tabs to free the pieces. fitting the pieces togather as the slices made it easy with the labeling. the result.
Things I have learned
Files

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