Laser Cutting - Machine Tutorial by qbicfablab

PAG. 1-3 PAG. 4 PAG. 5-8 PAG. 9-16 PAG. 17 PAG. 18

Introduction Safety Precautions Getting Started 1.Preparing the Design Getting Started 2. Operating the Machine Press-Fit References

Introduction

Tasnim Hussain | FAB Engineer Ghassan Yossef | Technical Guru 06| 19| 2018

Q1| Q1-1| Laser Cutting Machine LC 1390S | Cutting Machine DESIGN SOFTWARES (OPEN SOURCE | LICENCES) : LaserCut (https://cnctuts.com/blog/laser-machines/download-free-lasercut-5-3-and-installation-process ) PLATFORMS: FAB FOUNDATION REFERENCES: Pending

MACHINE DESCRIPTION The G.WEIKE LC1390S is a high precision laser cutting machine that focuses a high energy laser beam onto a material resulting in a high quality and dimensionally accurate cut. The laser cutter can be used to cut, etch, engrave, drill and to cut a variety of materials. Generally laser cutting machines contain a carbon dioxide (CO2) laser that produces invisible laser radiation at a wavelength of 10600nm in the infrared spectrum. The LC1390S has a maximum cutting area of 1300 x 900 mm, uses laser power of 800 W and operates at 110-220V - 50 and 60 Hz AC supplies. The machine has a very thin focal point of 0.2mm width, this makes the machine highly precise and convenient for all kinds of precision instrument industries. Unlike other milling technologies, laser cutting is superior due to the cleanliness of material cutting which leads to material saving from being lost while milling. Furthermore, it has a very fast cutting speed of 0-24000 mm/min which greatly minimizes the time needed for cutting. http://www.gwklaser.com/pdf/LC1390.pdf The LC1390 can be used to engrave and cut List of materials shown below:

Cardboard

Uncoated Paper

Matboard

Acrylic

Plywood

Basswood

Hardwood

MDF

Masonite

Cork

Leather

Glass

Tasnim Hussain | FAB Engineer Ghassan Yossef | Technical Guru 06| 19| 2018

Materials cannot be cut with laser cutter: ● ● ● ● ● ● ●

Most metals cannot be cut with the laser cutter. The two exceptions are thin sheets of stainless or spring steel. Polycarbonate (PC, Lexan) as it produces toxic fumes. Any material containing chlorine such as PVC and vinyl. Glass and Fiberglass can only be engraved. Printed circuit board (FR4 and other material types). Carbon ﬁber. High-density polyethylene (HDPE) thicker than 1/16".

Cutting Parameters: Simple 2D designs or non vectorized drawings are not informative enough to enable the laser cutter to cut or engrave any object. In order to create a laser file, creating a vector file is needed. Vector files can be easily created using dedicated software like LaserCut or using free vector files from a website like Noun Project. The most important tip is to follow the design guidelines of the material being used as each material has specific constraints that are necessary to take into account. For instance, the kerf that the laser creates while passing over the material should be considered and the size of the object should be checked to ensure that it does not exceed the size of the cutting area of the machine. Most importantly, the laser power and speed should be adjusted carefully to suit the material type and to serve the laser design safely without risks of burns ar fire. The following table shows different power and speed ratings applied to different materials available in the lab using the LC 1390S.

Settings in the Software

Settings in the Machine

Material

Speed

Power

Speed

Power

Plywood (3mm)

25%

100%

MDF (3mm)

30%

100%

MDF (6mm)

100%

80%

100%

Acrylic (3mm)

20%

100%

Acrylic (5mm)

100%

Felt Sheet (3mm)

100%

30%

100%

Cardboard

20%

100%

Tasnim Hussain | FAB Engineer Ghassan Yossef | Technical Guru 06| 19| 2018

Laser Cutting Laser Cutting is a digital manufacturing technique for transforming a 2D design into a physical object. This technology can be used over a wide range of materials with very high precision and clean ﬁnish. It can cut with a minimum thickness of 0.2mm. Advantages of Laser Cutting: ● ● ● ● ●

Cutting on a wide range of materials of different thicknesses Very precise work Material saving High speed of realization Ability to cut and engrave

Laser Beam Cutting Gas Work Piece (Material) Kerf

Types of Laser Cutting: There are many types of laser cutting; however, the following are the most commonly used techniques: ● Fusion Cutting ● Oxygen-assisted Cutting ● Sublimation Cutting

CO2 Laser Cutter Operation: The laser beam is a column of very high intensity light of a single wavelength or color. For CO2 laser cutter, the wavelength is infrared light to have the beam invisible to human eye. This beam is generated from the laser resonator at about ¾ of an inch in diameter and then travel through the machine’s beam path. Then the beam may be bounced in different directions by a number of mirrors, before it is it is ﬁnally focused onto the plate. The focused laser beam goes through the bore of a nozzle right before it hits the plate. Moreover, through the nozzle bore there is a compressed gas such as Oxygen or Nitrogen. By focusing the large power beam down to a single pinpoint, the heat density at that spot is extreme. The high power density results in rapid heating, melting or vaporizing of the material. The following ﬁgure illustrates the travelling path of the beam over the machine.

Safety Precautions

Tasnim Hussain | FAB Engineer Ghassan Yossef | Technical Guru 06| 19| 2018

Laser Safety Precautions: ●

Do not stare directly into the laser beam as serious and permanent damage may result to the optic nerve, cornia or lense. In case you experienced blurred vision, immediately seek medical attention.

●

Exposure to the laser beam may cause physical burns and can lead to severe damage. Proper use and care of the system is crucial for safe operation. Thus, always keep the machine door closed and observe the machine through the window while cutting.

●

Stay away from the machine and keep hands clear as serious physical cuts can occur.

Material Safety: ●

Fume exhaust/ extractor system is MANDATORY when operating the laser system. Fumes and smoke from the cutting or engraving process must be extracted from the laser system and ﬁltered outside.

●

Some materials can produce toxic or corrosive fumes when being engraved or cut, thus obtain the Material Safety Data Sheet (MSDS) from the manufacturer for every material you intend to process using the laser cutter. The MSDS discloses all the safety hazards when handling or processing a particular material.

●

NEVER leave materials in the laser system after laser processing has ﬁnished. Always remover all material including scrap material from the machine as they can lead to a ﬁre hazard.

To learn more about safety hazards, check out the following link: https://ehs.washington.edu/system/ﬁles/resources/laser-cutter-safety.pdf

Getting Started 1.

Preparing the Design.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

● STEP 1: Getting the 2D model ready As mentioned in the introduction, to prepare a laser cutting file, a vector file should be generated using a software like LaserCut. However, before using the software it is important to know that the a 2D model is needed. A simple 2D model can be sketched using LaserCut software. However, for highly customized design the 2D models are created using any modeling software like SolidWorks, Autodesk Inventor, AutoCAD or any other. Most importantly is to export the 2D sketch as a “DXF” file or “SVG” file. ● STEP 2: Uploading the design to the machine To upload the 2D model into the laser cutter, the following three are needed: 1- LaserCut 5.3 software which supports the machine controller. LaserCut 5.3: software is a Chinese developed solution to transform designs into machine code path sequence. The software comes with the machine. 2- USB Softlock to unlock the machine design software. USB Softlock is a USB device that looks similar to normal USB flash drive, it comes with the machine to enable you to use the LaserCut software, without this USB softlock the LaserCut 5.3 program cannot be operated on the computer. 3- USB Flash Drive to transfer the design to the machine. USB Flash Drive is a regular memory flash drive of 16GB max memory, since the machine does not support higher USB memory size. This flash drive is to store the machine code exported by LaserCut 5.3 to the G.WEIKE LC 1390S Laser Machine.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

The ﬁrst step is to connect the “Soft Lock” USB ﬂash drive into the PC with LaserCut software to enable using the software.

Open LaserCut and then click on “File” → “Import” to obtain the 2D design - as mentioned in the introduction- that is in the format of “.dxf” or “.svg”.

Then browse for the DXF ﬁle with the 2D design.

The design is uploaded into the LaserCut as one cutting layer. However, since there is text and two concentric circles, it is better to cut the parts from innermost parts to outermost parts.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

The design is divided into three different cutting layers by simply coloring each part with a different color.

The layers are rearranged from innermost to outermost using the “Up” and “Down”.

The default parameters for speed and power are adjusted to suit the material type -acrylic in this case- and the task. E.g. engraving needs slower speed and smaller power compared to cutting.

The same steps are done for the two cutting parts to adjust the cutting speed and power. Change the default parameters to the parameters shown in PAG. 2.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

The ﬁle is then downloaded and exported to obtain the laser ﬁle.

The ﬁle is then saved into a USB ﬂash drive to be able to process it with the laser cutter.

Getting Started 2. Operating the Machine.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

POWERING UP THE LASER CUTTER It is a paramount importance to power up the machine in the right way as this will help avoiding serious damages and maintaining the safety of the machine especially the laser tube. In order to safely power the machine, the four steps listed below should be followed: 1- Power up the laser tube chiller/cooler. 2- Power up the air compressor. 3- Power up the laser machine. 4- Power up the smoke ventilator (Ear protection required). *Note that the powering should be done in order from 1 to 4, wrong sequence might damage the machine. The fourth step could be done right before cutting any part. LASER CUTTER ANATOMY

The G.WEIKE Laser Machine consists of two panels, each panel is associated with a different section of the machine. 1- The Laser Machine Front Main Panel 2- The Laser Machine Nozzle Control Panel Detailed Description: Laser Machine Front Main Panel This panel can control the main features and functions of the machine. 1

Laser machine power switch

Machine control key panel

LCD display screen

Machine motion control for (X, Y) axis & homing button (XY-0)

USB softlock storage pocket

Emergency switch

* Note: the red (X) crossed section is unusable. 09

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

Notice: 1- The laser machine power switch is powered ON when turned in the clockwise direction and powered OFF when turned in the counterclockwise direction. 2- The machine control key panel: this panel has many buttons with the following functions

Key

Functions

Display laser machine functions menu.

ENTER

Entering and conﬁrming parameter input.

ESC LASER

Escaping/Exiting from current function, parameter setting or display. Shoots laser (DANGEROUS) do not use it unless necessary for maintenance and troubleshooting purposes. Keep out from laser beam pathway.

TEST

Moves the nozzle around the artwork working area..

FILE

Displays the list of ﬁles uploaded “artworks”.

START

Start cutting the design.

STOP

Stop cutting the design.

3- The LCD display screen displays selection, ﬁle, parameters, functions etc. 4- The machine motion control buttons has two modes of functionality, these functionalities are switched by ESC & ENTER key. By default when the machine starts after homing position is achieved, it goes into LCD interaction mode. Then by pressing ESC, the keys with switch to Axis motion control, and by pressing ENTER again they keys goes back to LCD interaction -The steps in the following pages will demonstrate more-. Interact with LCD display to select and change parameters values Left (←) & Right (→) switches between displayed parameters. Up (↑) & Down (↓) change, increase or decrease parameters values. (XY-0) does nothing Controls the axis motion Left (←) & Right (→) controls the X axis. Up (↑) & Down (↓) controls the Y axis. (XY-0) moves the machine axis to homing position.

Laser Machine Nozzle Control Panel This panel is only associated with the nozzle head, controls its height and probes the material surface height from the bed. Adjusting the Z axis level should be done with special care as the nozzle head can get damaged if not properly used.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

1- LCD screen 2- Nozzle motion control keys Up (↑) & Down (↓) controls the Z axis. 3- Restart is used to restart the machine..

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

The ďŹ rst step is to power ON the laser machine.

Secondly and the most important, is to turn on the chiller to cool the machine while cutting.

Thirdly, the compressor is turned ON.

Then the ventilator is powered ON to extract smoke and fumes produced from cutting or engraving.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

Click “ESC” to switch from axis motion control to interaction with the LCD screen.

“FABLAB” ﬁle is selected by pressing “ENTER”.

All files with the format “.MOL” is saved in the USB flash will show. Using the right and left arrows to navigate the desired file.

The ﬁle will take few seconds to be downloaded to the machine.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

Then the LCD will display some basic parameters of the laser ﬁle.

Press “ESC” to exit the LCD interaction mode and to move to the axis motion control. The button (XY-0) is pressed to move the machine axis to homing position.

The material is inserted into the cutting area of the machine.

After that, “TEST” yellow button is clicked to visualize the cutting area before start cutting the design.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

Then the Z axis is adjusted by lowering the nozzle head to reach very close distance from the cutting surface/ material.

The nozzle should be around 2mm proximity to the surface.

After adjusting all the parameters, the door is closed for safety purposes.

Click â&#x20AC;&#x153;STARTâ&#x20AC;? to begin cutting the design.

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

The engraving and cutting will take few minutes and it is done in order from the innermost to the outermost as speciﬁed in the design.

After ﬁnishing the laser design, the LCD will show the time consumed to do the tasks. Before switching OFF, press “ESC” button.

The pieces are left to be cooled and then they are removed from the machine bed including the scrap material.

Finally the machine is powered OFF.

Press-Fit

Tasnim Hussain | FAB Engineer 01| 01| 2019

PRESS-FIT Fab Foundation Link: http://fabacademy.org/2018/docs/FabAcademy-Tutorials/week3_computer_controlled_cutting/press_fit.html When a 3D model is being cut using laser cutter, the points of contact (joints) should be designed in a special way to allow the parts of the model to be snapped together. This is called interference fit, which is sometime referred to as press-fit or friction fit. It is the fastening between two parts which is achieved by friction to assemble the parts of a 3D model. Depending on the material and its thickness, the fitting value may vary from 10-50 µm. Following is a simple example to demonstrate the concept of the press-fit construction using a 3.8mm thick cardboard. SolidWorks software was used to draw and extrude a simple triangular modular element. The design was then exported as a DXF and was opened in Inkscape software to manage the fitting of the slots. Accounting for the kerf, the slot or the hole width was made 3.5mm (less than the thickness of the material) to provide a good fit of parts when being assembled to make a 3D model.

The triangular element is cut several times with the laser cutter.

The 3D assembled object after press-ﬁtting.

References

Tasnim Hussain | FAB Engineer Ghassan Yousef | Technical Guru 06| 19| 2018

Press-Fit: http://fab.cba.mit.edu/classes/863.10/people/brian.mayton/02.html Kerf Bending: ●

https://www.troteclaser.com/en/knowledge/tips-for-laser-users/bending-technique/

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https://www.instructables.com/id/Curved-laser-bent-wood/

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https://www.ponoko.com/blog/how-to-make/how-to-design-a-living-hinge/