week03.md

# 3. Computer controlled cutting

## **Instruction**

characterize your lasercutter's focus, power, speed, rate, kerf, joint clearance and types

## **Lesercutter we used**

The following is information of the Lasercutter used at Fablab Kannai.

![](../images/week03/lasercutter.jpeg)

Universal VLS 2.3

- Work area is 406x305x102mm(16"x12"x4")

- 30W CO2


## **focus**

![](../images/week03/focus.png)

- Lens: 2.0 inch (2.54 x 2 mm)
- Z Axis resolution 0.1mm
- Defocus +5.0, +4.5, +4.0, +3.5, +3.0, +2.5, +2.0 +1.5, +1.0, +0.5, 0, -0.5, -1.0, -1.5
- material we used : card board

![](../images/week03/laser_1.png)

Set Z=0.6 as starting point(zero) and change z parameter by 5mm
Unexpectedly, there is not a significant difference from the front viewpoint

![](../images/week03/focus_board.jpg)

However, looking at the back we find the board is not cut enough above 3.5mm
![](../images/week03/focus_result.jpg)

## **Power, Speed, Rate**

The data we used for power, speed, rate test

 - Power is laser output strength
 - Speed is speed of advancing laser
 - rate is PPI = pulses per inch

![](../images/week03/psr.svg)


Only the column of power=40 is displayed and Command +P

![](../images/week03/laser_1.png)

Launch UCP software and select Medium Density Fiberboard at material database

![](../images/week03/laser_2.png)

Cut the cardboard in each setting

![](../images/week03/laser_5.jpg)

We found that the best setting for this cardboard is here
**Power=70, Speed=20, PPI=250**

![](../images/week03/laser_5.5.jpg)


## **kerf**

In order to measure kerf, we use the data below.

- 10 sticks (11 cuts)
- 1/2 + 9 + 1/2 = 10 Kerf

![](../images/week03/kerf_test.png)

Cut the cardboard in the setting below
**Power=70, Speed=20, PPI=250**

![](../images/week03/laser_6.jpeg)

but the part of cardboard was not cut completely

![](../images/week03/laser_7.jpeg)


So we try again to cut it under a little stronger setting :
**Power=70, Speed=10, PPI=250**
This time I was able to cut it off completely.

lay them side by side and measure the total lengry by digital caliper

![](../images/week03/laser_8.jpeg)


10 Kerf = 100 - 97.55 = 2.45 mm

**kerf = 0.245 mm**

## **Joint Clearance for press-fit**

Measure thickness of the cardboard 5 times and calculate the average for them

2.9
2.83
2.85
2.88
2.79

ave.
**thickness = 2.85**

We use the data for joint clearance test
![](../images/week03/comb-test.png)

Set the result of experiment as parameter of thickness and kerf
![](../images/week03/laser_8.5.png)

Cut the comb
![](../images/week03/laser_9.jpeg)

and we test which slit is the best fit

![](../images/week03/laser_10.jpeg)

As a result, we get the final answer of the joint clearance as 0.1.

So I found value of the best slit width below

Thickness 2.85

-Kerf 0.245

-Joint Clearance 0.1

=2.505

## **What we learn**

to [Yukiya's individual site](https://fabacademy.org/2022/labs/kannai/students/yukiya-yamane/assignments/week04/)


## **Files we used**
- [Power, Speed, Rate test](https://fabacademy.org/2022/labs/kannai/Instruction/images/week02/fa2021-group-assignment-power-speed-ppi.svg)

- [Kerf test](https://fabacademy.org/2022/labs/kannai/Instruction/images/week02/fa2022-group-assignment-laser_kerf_x10%20.f3d)

- [joint clearance test](https://fabacademy.org/2022/labs/kannai/Instruction/images/week02/fa2022-group-assignment-comb-test.f3d)