Computer Controlled Machining
week 7 Group assignment is to do our lab's safety training test runout, alignment, speeds, feeds, materials, and toolpaths for our CNC machine
Fab lab Kochi has a 3 axis wood CNC by ShopBot.This is the most dangerous machine that uses for the Academy.Operating a larger wood cnc machine is new for me,never done before with beasts like this .ShopBot has a bed size of 4x8 feet or more and supports material like timbers,plywood,MDFs and some soft Aluminum etc...
The below picture shows the spindle and its moving axis directions and other parts as well.
A PC is attached with the machine for easy Machining.which include the ShopBot driver and V carve Pro CAM Softwares etc..
The red color table shelf is the tool box of the ShopBot where all the tools like endmill bits,collects,other tools are stored.There is an 3 manual control interface of ShopBot placed top on the toolbox table which include start,Reset buttons and Emergency Stop button.
these switches for resetting the connection of entire machine and also for starting the spindle.If something gone wrong We have to hit hte Emergency stop switch
This is where all of the main controls section of the ShopBot embedded which include stepper drivers,power supplies,VFDs etc...
These spanners use for attaching endmill bit to the ShopBot spindle.One for holding the collect chuck one for holding the spindle shaft.An electric switch key connected to the Collet chuck spanner for safety.Tht's u cant use the spanners without turning of the spindle.these key lock can be found on the control box of the ShopBot
Press fit Testing
For understanding the machining rules of ShopBot we done a test cut which include pocketing,Inner-cut,outer-cut,wood joint press fit etc... So,We designed a test jig with some holes and press fit key on fusion 360
The material thickness that provides in kochi fab lab are 12 mm and 18 mm thick plywood sheets of 8x4 foot.so We the design was done in parametric according to the thickness.we done our test in a pice of 12 mm plywood
The below picture shows the dimensions of the pockets,holes,and the wood joint jigs etc..
After the designing we exported the sketch of the 3D drawing face to DXF format and loads in to the V carve Pro software in the ShopBot PC
After loading the material on the bed we starts to set origins of all axis,starting from x,y .We sets the X,Y origin manually at the corner of the material we loaded .
for Z probing we can set either manual or auto probing.ShopBot has a auto z probe feature.A wired aluminum plate which connected to the controller used for z probing so first we checked wether it detects any contact or not.That's for making sure the z probe working or not .other wise there is a chance that it gonna break the bit.
then we paced o top of the work stock and also under the endmill.It gonna slowly lower the z axis till it touches the plate
while the z probe came down we pause the machine and made sure the plate is directly under the end mill,then we continued the machine
After the probing the machine is ready to cut we moved the machine back to home and started to cutting the press fit test file
After done the cutting the machine went back to home and turned of the spindle it self then we checked the result and we found out that it didn't cut through.
we realize that we forgot to measure the material before loading to the ShopBot bed . so we increased the cutting depth to 13 mm by editing the tool path and ran the machine again
This time All went well and the results are better, we taken it out from the Stock material by breaking the tabs using a chisel.One of us got a scar by wood chips while taking the cut part out so remember the safety,Wear the wood safety glows
Then we sanded everything using a 100-120 Grade SAND paper and also using a FLAT File then finally used the sander machine for a better finish surface without removing too much material
Then we tried to insert the key in the different joints
The key perfectly fits in the bigger '12.4 mm' slot with a good press fit.Actually it must be loosen in the slot but then we found out there is an error with the end mill too that we used for cutting.The endmill isn't exactly 6 mm