5.Group Assignment - Large format CNC¶
We have been discussing CNC cutting this week as one of the computer-controlled cutting topics. Computerized Numerical Control or CNC for short, is a type of pre-programmed software and code that regulates how industrial machinery moves. As a result, the instructors discussed the theory behind CNC and its applications.
We practiced using a CNC machine by cutting and engraving a piece of wood with several settings so that we could compare them and select the best one.
Safety | Before start cutting¶
Safety¶
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Safety glasses are necessary for protecting our eyes from flying splinters.
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With sound-isolating headphones, you can protect your ears.
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If you have asthma or cannot tolerate dust, wear a mask.
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Be careful to roll up your sleeves.
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Make sure you are behind the gleaming line in the ground when the machine is operating.
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Remove anything on or near the device
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Additionally, if something goes wrong, you may stop the machine quickly by pressing the emergency stop button (Those found on the machine itself or beside the computer screen).
Before start¶
1- Choose a piece of wood and secure it.(Each of us put a screw in one of the edges)
2- Put the key in and rotate it to the right so that it engages, otherwise, the machine will not work
3- Turn the red button to set it to the on mode
4- Set the axes to zero (x=0, y=0)
5- To fix the z-axis, use this tool, which is situated on top of the CNC. Put it below the drill and set the z-axis in the CNC program. The equipment can detect the electric circuit that is created.
Step 1:
Step 2: (Connect it as shown in the figure, right or left)
Note Make sure not to put it like this (As picture shown below); because it may be dangerous.
Step 3: Click OK (hit Enter) to complete the process successfully
Test | Engraving¶
Design¶
We drew a rectangle with the letters in our names on it, and we’re going to experiment with different settings to see which works best.
We created it as a test of the CNC machine’s effectiveness, namely the impact of changing the feed rate and speed on the result.
Test data¶
While the rotational speed ranges from 12000 to 19000 RPM, the feed rates range from 60 to 100 in/min.
Feed rate and rotation speed | Test Data
| Letter | Spindle Speed | Feed Rate |
|---|---|---|
| Z | 12000 | 100 |
| A | 14000 | 100 |
| M | 16000 | 90 |
| S | 17000 | 90 |
| G | 19000 | 70 |
| B | 13000 | 60 |
If the selected depth for the number of passes is more than the thickness of the testing sheet, a warning can appear. Ignore it since the sacrificial sheet’s being will shield the machine from harm and ensure thorough cutting; take notice that the extra depth was introduced to guarantee the cutting process’s success.
Whats went wrong¶
After a few minutes of operation, the machine suddenly stopped. The notification displays as seen in the image below; we connected all wires and restarted.
Result¶
It is clear from the image below that the letters differ in form and degree of accuracy after being created using a CNC machine.
Test | Joint fitting¶
Since most of CNC projects for this week require joints for all the pieces to be put together, another test was made to find the perfect fitting for the joints.
Knowing that the thickness of the wood used is 12 mm, the design was with (number) different fittings ranging from (number - number)
Joints used in the design are (Mortise and tenon) joints.
After cutting the test design and trying it, it was fount that Mortise gabs of 12mm was the best fit.
Note: for different types of projects, different joints might be used.