Computer Controlled Machining

Assignment

Make Something BIG

SHOPBOT @ LAST!!!

Shopbot is something i have been wanting to try since i joined the fabacademy and the finally the time has come.
machinised cutting of wood makes it really easy to get good results in a short time.




We have a white board in our lab. I want to build a supporting stand for that board.
Herez a pic of the board as well as the design sketch-



I decided to use the Autodesk mechanical for designing.This was my first time using the software, but it was pretty easy to learn.
Also, for the participants of fab academy, there is a 1 year free license available for all autodesk produts.Here is a download link for all autodesk softwares-Autocad
My first design for the supporting stand was flawed.



I had made the back support leg slanding 20degrees but there was no support for the leg making it liable to break from excess weight. So i redesigned and made an arc support for the back leg and curved the front end also. Also filleted the end section so that the sharp edges were removed, for extra safety.I then made 3 more copies if the design and positioned them so as to maximum utilise the wood board and to reduce wastage.



AutoCAD Design FIle-stand


Now that designing was done, The next step was cutting the wood using shopbot. I had saved the file in .DWG format. I opened the file in the shopbot pc using the v-carve software. It is best to create a new file in v-carve and copy the design to this file. make sure that the new file has the same dimensions of wood used for cutting.now arrange the copied files carefully so that the wood will be fully utilised and thus decrease wastage.The wood can either be fixed using nails or by using vices.Make sure the wood is tightly attached to the bed so as to decrease the effects of vibration.
For cutting my design, i created 3 profiles in v-carve-the outer profile,the inner profile and the drill profile. A specific no of taps must be given to the outer profile so that the pieces will be held down even after cutting. The taps can be hammered out after the cutting.



It is best to arrange the sequence of operations in the following order: drill, inner profile, outer profile. ALso make holes in every joint edges, the diameter of the hole being the same as the drill bit size. This holes will make the filling of pieces much easier. After completing all this, I saved the 3 profiles to a single toolpath.



The next step was to set the tool bit, speed and feed rate.There is a toolpath tab on the upper-right corner of the vcarve software. Select this, a section will appear on the roght side. It contains various menus regarding the profiles, vectors, surfaces, etc. Select Tool database.
I selected the 1/4" end mill bit, spindle speed to 12000r.p.m, feed rate 0.5.The wood had 20mm thickness, so i set the cut depth to 22mm.



next i opened the shopbot software. The software will automatically detect the shopbot so make sure that the shopbot is powered on.There are a few processes to follow before operating the shopbot-set the x-axis, y-axis and z-axis.There is a virtual keypad which can be used to move the shopbot head.If you are new to the shopbot operation, make sure that you operate the machine in the presence of your instructor or else there is a very good likelyhood that there will be some mistakes resulting in damage to the machine.



When the pre-cutting steps have been completed, load the saved toolpath and start cutting. Always be present while the machine is cutting lest some poblem occurs. While i was cutting, there was a slight mishap and i broke the drillhead. On the bright side, i got to learn how to change the drill bit.

The hard part as all over. Now it only remained to hammer out the taps,



smoothen the edges of the pieces using a sandpaper,



assemble the pieces, and VOILA!!! A nice, fit stand for our white board. Pretty nice right?!!!!





I also designed and built a laptop table which could be used while lying down.I have been wanting to build this for some time since i frequently use my laptop while lying in bed and it was hard and uncomfortable to use while lying down. But the problem is solved now. Here are the pics and design files for anyone who want to make one.



Lapstand Design FIle-lapstand



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