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Week8. Computer Controlled Machining
assignment
group assignment:
test runout, alignment, speeds, feeds, and toolpaths for your machine
individual assignment:
make something big
Equipment
• Hardware: shopbot
• Software: V-carve pro, FreeCAD
1. V-carve Pro
- This program can make a G-code file and configuration about endmill parameters for toolpaths.
2. test runout, alignment, speeds, feeds, and toolpaths for your machine
To take this data(runout), I just read datasheets of shopbot CNC machine and
read more documents about to explain cocept for technical terms as mentioned above.
First, I try to measure runout of endmill(10mm diameter) nearest position of shank
with no powered state , setup dial guage meter(0.01 mm units) and reads variation of
scales manually, for the reading accuracy need doing to it several time what reads
match the meaning as below show.
By the way, TIR means that runout of edge of endmill flute assembled in motor axis
so I check about length of from center point of rotation to end of endmill.
And make a calculation to get TIR. Calculation chart and measurements shows below.
In this section, we have pre calculation for experimentally to find good value of
feedrate and spindle speeds. We have also read about the document treat the chip load chart.
It gives us for about chip load range for our material that is softwood or flywood.
Reference document : ChipLoadChart.pdf
Now, we tested about good condition to find speed and feedrate for various combination of both.
We discussed about the result of chip load size and spindle sounds and finally to get some range.
The best feedrate is :
• At 15000 rpm: 100 IPM
2. design modeling
3. Make toolpaths
To make a toolpath, I use vcarve program. At first, import some path design file and edit the paths
for each shape. In this step, also check endmill paarameters, make sure the variables as followed above
feedrate and speed for the best result. If to think about the situation after mill each parts, optionally
put some toolpath tabs on each shapes. After check about simulation of milling, save the work file for
shopbot CNC.
3. machine work
4. assembly
5. Add more bigger model work
