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Lasercamm Guide

A Word of Caution

 

The Lasercamm cuts material using intense heat and compressed air to remove molten material. Due to the potential for fire, never leave the Lasercamm unattended while in operation.





Only cut approved materials such as acrylic, wood, paper, and foamcore (Please ask if you have any questions). Avoid reflective materials such as metal (which will reflect back to the laser and damage it) and those which release toxic fumes when burned (i.e. PVC).



 

Whenever you cut a part in the Lasercamm please cover any portion of the honeycomb bed that you do not use. This keeps flames down and smoke off of the laser optics. Please see EXAMPLE

 

 

 

See what happens when you don't use the Lasercamm bed covers. Picture 1 Pictures 2

 

 

 

Wait 30 seconds after the cutting is completed to allow any toxic fumes to be exhausted before opening the lasercamm cover.

 

 

 

In Case of an emergency, press the big round red EMERGENCY STOP button to cut power to the entire system.

 

 

 

Press the small square red STOP button to simply stop cutting and return the cutting head to its starting position.

 

 

 

The honeycomb bed of the Lasercamm is delicate and costs $700 to replace. Place parts on it with care.

 

 

 

The Lasercamm costs 100,000 dollars. So please take good care of it.

 

 

 

Remember, this guide is only an overview! The complete Lasercamm manual is located in the Design Studio next to the Lasercamm.

 

 

 

And of course, when in doubt, do not hesitate to ask the Design Studio Manager Chris Cassidy, Professor Delson, or your tutor/TA

 

 

 

 

Use Guidelines

 

We only have one Lasercamm machine, and over 300 users per quarter!

 

 

 

Use the Lasercamm computer only for transferring your .dmc file to the Lasercamm machine. All other CAD processing should be done in the computer labs. (EBII-203 & 239)

 

 

 

Shop etiquette will go a long way - clean up after yourself and always put shop tools away in their proper locations.

 

 

 

Please think of others. Keep the honeycomb bed clean by vacuuming it after every use with the vacuum next to the Lasercamm.  Please see image.

 

 

The Lasercamm is primarily for MAE class use.  For other UCSD uses please contact the Design Studio Manager Chris Cassidy or Dr. Deslon at ndelson @ucsd.edu

 

 

 


The Basic Steps to Making Parts on the Lasercamm

 

STEP 1a: Drawing and Saving Your Part

 

Draw your part in AutoCAD just like you would draw any other 2D drawing, but without center lines and hidden lines.

 

 

 

 

 

 

DO NOT use templates. The large number of layers will confuse the Lasercamm and you!

 

DO NOT create regions. The Lasercamm uses entities only!  Make a separate copy of your AutoCAD file if you will be using regions for analysis.

 

NEVER NEVER NEVER move the Universal Coordinate System (UCS)!!!!!   This will confuse the Lasercamm software.

 

Make sure all your parts are above the X and right of the Y axis of the coordinate system. The Lasercamm software will let you draw parts outside of the machines cutting area but it will not cut them. Remember to keep your parts within 0",0" to 48",24". It's the size of the Lasercamm bed.

 

Use layers to distinguish between cutting and scoring lines.  A cut goes all the way through the part, while scoring just marks the part. 

 

Also use layers to distinguish the order the cuts are to be made.  Internal cuts (such as center holes)  should be cut first because the part will move slightly once the outer edge is cut.  Step 2 will explain how to specify the cutting order.

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More than one part may be contained within a file, and parts may share the same line. Organize the layout to save raw material.

 

The thickness of the laser cut is about .012", and therefore the final dimensions of your part will be slightly smaller and holes a bit larger.

 

Entities other than lines, circles, and polylines must be exploded (under the Modify menu) in order for the Lasercamm to understand your drawing.

 

DO NOT use AutoCAD text or dimension entities in the drawing. The AutoCAD format for lettering is so detailed that it can generate vibrations that can damage the leadscrew mechanism of the machine.

 

Save the finished part drawing to a USB drive as an AutoCAD Release 2000 .dxf file (Under File -> Save As...). This lets the Lasercamm software read it with the least amount of trouble.

 

Also use simple file names for your .dxf files and folders on your USB drive. Do NOT use special characters. Use only letters and numbers. Never use more then 8 characters or numbers for your file and folder names. Never have your files in folders more then two deep on your USB drive. The reasons for this is because it can cause problems when you go to send your files to the Lasercamm for cutting.

 


 

STEP 1b: Good Practices to Folow

 

Keep cutting times to a minimum - Everyone does not want to wait forever for the Lasercamm to cut out parts.

 

AutoCAD's Polyline feature allows you to create a more efficient path for the Lasercamm to cut by having adjoining lines cut in sequence

 

 

To create a Polyline, type "pedit" and Enter at the AutoCAD command prompt. Click on the first entity to be joined, press ENTER, then press "J" and then ENTER. Now select the entities in the order that you want them cut by the Lasercamm. Press Enter when done.

 

 

Clicking on the Polyline you just created will show one large entity instead of many small entities.

 

 

To Undo the Polyline join function, use the EXPLODE command at the command prompt.

 

Always position you parts as close to the origin as possible in AutoCAD before saving it to a ".dxf" file. Otherwise, you will end up with parts cut out of the middle of your acrylic, making it hard to cut anything else out of it.

 

The laser thickness is only .012 inches, so you can place parts very close to each other or draw your parts so they share common lines.

 








 

 

STEP 2: The Lasercamm Software: The Lasercamm software is located on the computers in the Design Studio (EBU2 Room 315). Only .dmc cut files created on the computer directly connected to Lasercamm 2 will work on Lasercamm 2.

 

 

The Lasercamm software is used to convert the AutoCAD generated .dxf file into a .dmc file which the Lasercamm can read.

 

Important: To cut parts on the Lasercamm you must use the computer across from the Lasercamm machine to send your .dmc files to it. This computer is reserved for this function only! You should always use the computers in the computer lab L203 and L239 to generate the .dxf and .dmc files needed to cut your parts.

 

To launch the Lasercamm application, from the START menu, select PROGRAMS, then LaserCAMM Model 2405 Lasercamm software screen shot

 

From the screen that comes up, select LOAD and then select your .dxf file.

 

When your file is opened you will see all of the layers you made in your AutoCAD drawing.

 

Now you have to assign what you want the Lasercamm to do with each layer.

 

You will have Four Pulldown menus:

 

 

Materials : Set it to the material you are using. It will most likely be Acrylic for most of the stuff we'll be doing.

 

 

Thickness : Set it to the thickness of the material you are using.

 

 

Operation : Set it to what you want the laser to do. i.e. select cut to cut the material, score to etch.

 

 

Power : Just leave it at 100%

 

 

After making all of your choices in the pull down windows, click OK.  As you define each layer, the Lasercamm software will create a new .dmc file for that layer.

 

If you had multiple layers and multiple .dmc files were generated, you can now combine all of the individual .dmc files into one big .dmc file. Use the Combine button from the Lasercamm interface window. Then select Add Files to load the appropriate .dmc files. Select the files in the order in which they are to be cut by the Lasercamm machine.

 

The circumference of a part should be cut last, since the part will separate from the raw sheet and move slightly.  For example, if you are going to cut out a gear or a wheel, the inner holes should be cut 1st and the outer gear teeth or wheel surface should be cut last, otherwise the whole part may move in the cutting process, resulting in a wheel or gear that wobbles.

 

Now you can view your part! If you can't view your part it will not cut on the Lasercamm.

 

Select the VIEW button and then select the file you want to view. NOTE: You can view the individual layers with their corresponding .dmc files or the combined .dmc file that you created.  Also when you view the Combined .dmc file you will notice that each layer is a different color. Here is the color order that Lasercamm uses for cutting out your part when you preview it:  Yellow, magenta, red, cyan, green, blue, dark gray, light gray, brown, and purple.  The white dotted lines show the path movement of the Lasercamm cutting head when it is moving but not cutting.

 

Now you have generated a .dmc file that can be read by the Lasercamm.  Before heading to the Lasercamm Machine, you should check how much time your part will require to cut.  Select the ESTIMATE button and then select the file you want to check.  Most parts take between 5-15 minutes.  If your part is going to take more than 20 minutes, review the tips in the previous section on how you can minimize your cut time.  Otherwise, you may want to reconsider the necessity of such an elaborate procedure. 

 

 

 

STEP 3: Lasercamm Setup and Cutting Parts

 

A Quick Movie Introduction to the Lasercamm (THESE ARE VERY HELPFUL)

 

 

IMPORTANT: ALWAYS remain with the machine while it is cutting your part in case of an emergency!

 

Always be sure to read posted signs in the Lasercamm area giving special instructions and warnings!

 

ALWAYS go through all the checklists posted at the Lasercamm area. If you follow these lists, most of the problems you will have will be solved!

 

With the .dmc file you've already generated, and saved to a floppy, go to the computer across from the Lasercamm machine. Insert the floppy into the computer and double click on your .dmc file. Follow the "Initial Check List" posted on the wall behind the computer.

 

Place Raw material on the honeycomb bed and REMOVE the paper on the top side only.

 

 

  1. Align corner with the origin (0,0) in the lower left hand corner.
  2. DO NOT place any material outside the designated work area. This may interfere with the leadscrew operation and damage the machine
  3. The parts are held down by a suction force to minimize motion during the machine operations. To increase suction on the part being cut, cover the remaining area with a heavyweight non-curling material.
  4. Set the focal length of the laser to the thickness of the part being cut. Turn focusing knob on the cutting head, while reading the scale in inches. Always leave the Lasercamm focus as .25" when you are finished with the machine.
  5. Cover the unused honeycomb bed of the Lasercamm with the blue bed covers.
  6. Close the cover
  7. The laser will not operate with the cover open. DO NOT tamper with the safety switch on the cover.
  8. Press the green START button on the Lasercamm to begin cutting. When you press it, the fan to the fume hood will come on. It is pretty loud, so don't freak out and think something went wrong. It is normal.
  9. DO NOT operate the laser over a bare area on the bed. It marks up the bed and wastes the Laser charge. If the part is not aligned properly, press the small square red STOP button and reposition the part.
  10. To pause the cutting, toggle the PAUSE switch, to stop cutting the current file, push the stop button. Or in an emergency, press the large red EMERGENCY STOP button. Power to the Lasercamm will be turned OFF.
  11. Leave the cover closed and fan on for 30 seconds to exhaust any toxic fumes before removing your parts.
  12. Leave the power to the Lasercamm ON.

 



 












Laser Beam Physics

 

 

            One must understand the complexities and limitations of the Lasercamm CO2 laser beam in order to better comprehend how it works.  The laser beam is focused at one small point that should bisect the acrylic piece, as shown below.  You are adjusting the focus point of the laser when you screw the black knob on the top of it.  This focus point is where the acrylic is vaporized most efficiently, so it is important to adjust for the correct thickness of acrylic. 

            The thickness of the laser beam is between 0.010” and 0.020” and depends on the thickness of the part being cut.  The drawing below also demonstrates why you need to ream out your holes (or tap them) after they are cut on the Lasercamm.  The laser beam does not cut exactly perpendicular to the acrylic because of its focus point, so it is recommended to use the reamer for a precise, round hole.

 

 

 




 

Frequently Asked Questions (FAQ)

Lasercamm things to remember or common mistakes:

 

 

  1. The Lasercamm manual says to use the inverse order when you are combining your files to get the Lasercamm to cut them out correctly. I don't care what the Lasercamm manual says. NO, NO, NO! Don't do that. Just select the .dmc files in the order that you want them to be processed. The first one in the list will be the first one processed and so forth down the list.
  2. Remember to close your dxf file in Autocad before opening it with the Lasercamm program.
  3. Remember not to use templates.
  4. Unsupported geometry must be exploded.

 

 

 

Why doesn't all the geometry in the CAD file appear in Lasercamm?

 

 

The Lasercamm software cannot read combined features such as rectangles and ovals. remember to explode such items before creating your dxf files.

 

 

 

What is the Laser beam thickness and how does it affect my parts?

 

 

The laser beam thickness varies from .010" to .020" depending on the part thickness. Accordingly, the shape you cut out will be a little smaller than what you had drawn if you keep the inside of a cutout. Or, holes you've drawn will be a bit larger than what you had drawn. For increased accuracy, you can use the AutoCAD OFFSET command to scale your CAD shape by half the beam width.

 

 

 

The Laser beam is not showing up! What's wrong?

 

 

It is likely that the Lasercamm is malfunctioning. Stop and get help (Chris, Mike, Prof. Delson or a TA/Tutor).

 

 

 

How does the Lasercamm work?

 

 

A laser beam is directed through a set of mirrors to create the desired pattern on the horizontal place. The mirrors are moved along the X and Y axis with a large leadscrew mechanism that moves the laser head. An air jet blows material out and away from the beam after it is cut. A vacuum holds the parts against the honeycomb bed during the cutting operations, and removes fumes. The Lasercamm Web Site has a picture of the operation.

 

 

 

What is the accuracy and resolution of the Lasercamm?

 

 

There are two factors which affect the accuracy of the final part:

 

 

  1. How is the accuracy at which the center of the laser beam controlled. The specifications from the company indicate that the leadscrew resolution is within (+/-) 0.005"/ft
  2. The other factor that affects the shape of the part is the shape of the laser beam. The beam focus is best at only one horizontal plane and spreads out at other heights. Accordingly, holes will have a slightly conical shape. This factor can have a much larger effect on part accuracy. For example, holes that are meant to be press fitted should be reamed after being cut on the lasercamm.
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