Laserkalibrering

Calibrating the X700 lasercutter

The Bitraf laser cutter is from the Chinese company Redsail. To use the laser, training is required in the form of the laser-workshop. To learn how to maintain the laser, you should attend the Maintenance-workshop.

Maintenance

The most important thing to keep clean is the metal mesh that ventilates the cutting area. Clean with a wet cloth/paper and dry it after. If this is blocked, smoke will build up and that will reduce the effect of the laser. It will also stick to the mirrors, so make sure the cutting area is always well ventilated. Preferably - start each session by cleaning the mesh.

The second most important thing is to check that the mirrors are clean. We have special cleaning swabs available in the Laser supplies box. only use these, but DO NOT clean the mirrors excessively! Only clean them when they are visibly dirty since (just like glasses) they will become a little more matte with each cleaning. As long as the cutting area is well ventilated, you will rarely need to clean them.

Calibration

Over time, the optical system looses focus and the mirrors must be aligned. Once every two months will be enough, but be aware that this is a task not done by someone without extensive laser experience. If the laser is not cutting optimally, DO NOT try to focus it yourself. Instead contact Thomas or others in the Bitraf board and they will find someone to do the calibration (but you are very welcome to join in on the calibration session to learn!).

The process is simple, but time consuming. You'll need some white(ish) masking tape (or similar), clear tape and cleaning swabs. Calibration video of a similar laser

Step 1: First mirror mounting

(This step can be skipped if you are doing a minor tune up.) Goal: We want to make sure that the laser hits the first mirror.

The first mirror is right at the exit of the laser tube and it is fixed to the machine itself with 4 screws.

• Set the laser to pulse 0.2 seconds at 20% effect (if not already set).
• Open the cover hatches so that you can access the mirrors. IMPORTANT SAFETY RULE: Always close your eyes when firing the laser with any covers open or removed.
• Place a piece of masking tape over the entry hole of the target mirror you are trying to align the laser beam to. Make sure the outline of the hole is visible though the tape.
• Gently press PULSE. Each pressing of the pulse button will then leave a nice, little brown mark on the masking tape and you use this to align the laser beam. If you do not see a burn, double check that the main lid is closed or try pressing the button a little longer.

It is good enough if the mark is well inside the circular hole in the mirror mount. It does not have to be dead center. When you are ready to move on, clean the mirror surface gently with a special glass cleaning wipe.

If you are doing a minor tune up it is unlikely that you will have to do any adjustments in this step. If you have to you can loosen the four screws holding the mirror fixed to the machine and adjust it so that you hit the mirror with the laser.

Step 2: First mirror alignment (Y axis)

Goal: We want to make sure that the first mirror is sending the laser beam parallel with the Y-axis.

• Place a tape on the entry hole of the second mirror, which is the target of the first mirror.
• Run the Y-axis all the way up, so that mirror 1 and 2 are as close to each other as possible.
• PULSE the laser and make sure you see a burn in the tape. Mark it carefully with a pen.
• Run the Y-axis all the way down, so that mirror 1 and 2 are as far away from each other as possible.
• PULSE the laser and make sure you see new burn in the tape. If the mirror already is well aligned they might already overlap. If their center points are within less than a mm of each other, proceed to the next step.
• Tweak the angle of the first mirror in the correct direction using the adjustment screws. (TODO: Draw a picture showing how to find which screw to adjust.)
• Repeat until the center points of the burns are within less than a mm of each other.

When you are ready to move on, clean the mirror surface gently with a special glass cleaning wipe.

Mirror adjustments screws

Each mirror has 3 adjustment screws and two fastening screws. The fastening screws have a spring resting on a disc. The screw should not be fully tightened. It needs to apply pressure, but be flexible so that you can tweak the adjustment screws. Each screw also has a locking ring. When calibrating, it's useful to loosen this completely. As soon as a mirror is perfectly aligned/centered, make sure to fasten the rings as the movement of the laser will eventually vibrate the screws loose. (TODO: Try locking these better.)

Step 3: Second mirror alignment (X axis)

Goal: We want to make sure that the second mirror is sending the laser beam parallel with the X-axis.

• Place a tape on the entry hole of the third mirror, which is the target of the second mirror.
• Proceed as in step 2 but now move the X-axis instead.

Step 4: Third mirror alignment (Z axis)

Goal: We want to make sure that the laser is centered out through the "nozzle".

• Put clear tape over the exit hole of the laser nozzle
• PULSE the laser
• Pull off the tape and check if the laser hole is dead center in the mark the nozzle leaves on the clear tape. If you can not see the nozzle mark you might have to use water based paint and a piece of paper instead of clear tape.
• Adjust the third mirror and try again until the hole is centered

Step 5: Focus height

TODO: fill in details here in English. There are Norwegian instruction on the Laser wiki.

Finn højde hvor laser er i fokus