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lasercutter2

Laser Cutter #2

NOT YET IN SERVICE. TRAINING REQUIRED BEFORE USE.
(Note: access is enabled for people who are preparing the cutter for general use)

Model JD90125
Bed: 1250x900mm
Laser: 100-150W (130W rated, 150W peak) glass CO2
Accessories: CW-3000 chiller, rotary axis

large_laser_cutter.jpg

To Do

Before general use:

  • Create and fit a bracket to hold the air assist tube away from the drive belt
  • Clean laser tube water channels
  • Test optical power output and calibrate to a sensible maximum (e.g. 66% of peak rating)
  • Create chart of power/speed settings for common materials (as a basic rule, multiply speeds from the old chart by 3x)
    • Ply ✔
    • MDF ✘
    • Acrylic ✘
  • Documentation for existing laser cutter users
  • Update docs:
    • If Z-axis needs to be moved, take care not to crash into the nozzle. Releasing the nozzle locking ring will allow the nozzle to collapse instead of crashing.
  • Fix extraction
    • Fume extraction is unacceptable at the moment. Fumes or light haze will fill the room. This appears to be caused by fumes re-entering via the window, and not by lack of extraction in the cutter itself.
    • Possible solution: seal the window properly. Better seals have been installed and the situation is better, but not good enough.
    • Possible solution: divert the fumes up or down away from the window.

Soon, but don't wait:

  • Fit replacement alignment laser (ordered 6th April)
  • Fit extraction duct mountings on right-hand access door (order delayed, re-sent 10th April)
  • Create spare focus jigs (requires 12mm acrylic, or a new design)
  • Build and install monitoring system (laser usage, temperature logging)
  • Fully check and adjust alignment
  • Re-level bed.

Later:

  • Order spares: silicone tubing, mirrors, lens, rotary attachment o-rings
  • Purchase and install tinted polycarbonate window, 1185x920mm.
  • Install vent in G2 door to provide better air flow.
  • Upgrade internal (to chassis) extraction ducts (use PU ducts instead of foil, merge rear and hopper 100mm ducts into a 150mm duct for egress). Optionally replace flexible door-join with a foam seal. ACTION: MIKE
  • Upgrade cutter-to-blower duct to PU or semi-flexible aluminium 150mm. ACTION: MIKE
  • Install ducts to roof and upgrade blower, to avoid releasing fumes onto courtyard users. ACTION: AL, TO LIAISE WITH SUMMERHALL
  • Install LED lighting. ACTION: ALFIE
  • Replace broken acrylic cover on front-loading slot.

Guide for existing laser cutter users

What’s changed?

  • The bed is larger, up to 1250x900mm.
  • The Z axis is deeper, so large items can be engraved.
  • The laser is more powerful (estimated at 100W or more) so cutting is faster or thicker materials may be used.
  • A rotary axis accessory can engrave cylindrical items.

What do I need to know about using it?

  • We now have access control. All members will have access to start with (we might make a formal training record later). Non-members will need a member to enable the laser cutter before use.
  • Focusing the laser (for different materials) is slightly different. The nozzle can be adjusted without moving the Z axis. Users must still know how to adjust the Z axis in case it's been left too high or too low.
  • The enclosure is very large and smoke/fumes take longer to clear. Leave the case closed for 10 seconds after cutting to allow the extraction system to catch up.
  • The air assist is adjustable. Always make sure that it's enabled (on the top control panel) and that the valve (on the right hand side) is open. It's okay to reduce the air assist for delicate materials like paper, but there should always be some air flow enabled to protect the lens.
  • The window is clear. This should absorb the infra-red laser, but it doesn't block much of the visible flash when the laser hits the honeycomb bed. So don't stare directly at the cutting point.
  • The window is tinted as all hell. This should absorb the infra-red laser, and also absorbs literally all other light in the laser. You are encouraged to stare directly at the cutting point.

Checklists

Powering-Up

  • check that the bed is clear of obstructions
  • check that the Z-axis is below the level of the cutting head (we don’t want the head to crash when it attempts to home itself)
  • make sure that all the access panels are closed
  • switch-on the laser cutter at the wall
  • log-in with your access token
  • press the green start button
  • check that the air assist is switched on and that the valve on the right-hand side is fully open

If it won't start:

  • check that the door on the right-hand side is properly closed
  • check the emergency stop button (twist clockwise to reset)
  • check that the access control is logged-in (should say Idle or Active)

Switch off the cutter and report a fault:

  • if chiller alarm sounds for more that a few seconds
  • if the extraction fan makes flapping/grinding noises

Before Cutting

  • position the material on the bed and move the nozzle over the material
  • release the locking ring on the nozzle
  • place the 12mm focus jig between the nozzle and the material, and lower the nozzle down to touch it
    • if there isn't enough available movement of the nozzle, remove the jig, adjust the Z axis and try again
  • re-secure the nozzle and remove the jig
  • check that the air assist is switched on and that the valve on the right-hand side is fully open
    • the air assist may be reduced for delicate materials such as paper and card, but some air should be kept on to protect the lens from smoke

After Use

  • press the datum button to return the laser nozzle to it's home position
  • leave the system running for a few minutes to allow the fumes to be extracted and the tube to be cooled-down
  • remove any scraps from the cutting bed (use the vacuum cleaner if the pieces are small enough to get stuck in the honeycomb)
  • press the red stop button
  • press the logout button on the access controller

Troubleshooting

System won't start up

  • check the emergency stop (twist clockwise to reset)
  • check that the right-hand access panel (electrical controls) is closed properly
  • check that the rear access panel (laser power supply) is closed properly
  • check that the access controller is logged-in

Nozzle moves but doesn't cut

  • check that the lid is closed (the microswitch should make a click as it closes)
  • check that the chiller is powered-up, showing a green Normal status and that it is connected to the laser cutter
  • check that the correct power level has been selected

Chiller alarm sounds

At startup: if the alarm sounds for more than a couple of seconds, TURN IT OFF and report a fault. There may be insufficient water, there may be a blockage or a pump failure.

During use: if the alarm sounds during normal use:

  • pause the cutting session
  • check the temperature on the chiller's front panel (it should be in the range 10-23℃, roughly room temperature)
  • if the temperature is too high, try waiting for the chiller to bring the temperature down
  • if the temperature doesn't fall then there is probably a fault
  • even if the temperature does fall, REPORT A FAULT as the chiller should normally be able to keep up

Log

2018-03-25:

  • Moved into G2 and re-assembled

2018-03-30:

  • Extraction installed, laser tested.

2018-04-11:

  • New alignment laser fitted. Wiring partially replaced and re-soldered. Air tube re-secured.
  • Laser tube disinfected with water/Milton for an hour. Water channels still appear dirty.
  • Optical power tested.
    • 90% = 40mA = 132W
    • 66% = 30mA = 126W
    • 55% = 25mA = 116W (selected)

2018-05-04:

  • Proof-of-concept LED strip lighting fitted - to be replaced with a proper solution if it proves useful

2018-05-14:

  • Internal ducting upgraded (PU ducts, internal combiner to 150mm and 150mm to the blower). Significant improvement to extraction, but more testing is still required to see whether fumes are re-entering via window.

2018-05-15:

  • Mike found a leak in the flexible square section after the blower. It has been plugged with hot glue and seems to be fixed. The smell of fumes in the corner while cutting is reduced now, but still there. There may be a small leak where the square tube seals against the wood panel (on the left behind the blower).

2018-05-28:

  • Bed levelled.

2018-07-14:

  • New tinted window fitted: it is now safe to stare directly at the beam. Also at some point proper LED lighting was installed but wasn't logged.

2018-07-19:

  • The bed level was checked and it's within 1mm all over. The axes were checked and they're within ~0.2mm over ~200mm.

Other Specifications (for maintenance)

Water tubing: silicone, 12mm OD, 8mm ID, 2mm wall
Chiller: CW-3000
Air assist compressor: Hailea ACO-328
Air assist tubing: silicone, 12mm OD, 8mm ID, 2mm wall
Mirrors: 3x 25mm diameter
Lens: ZnSe, 20mm diameter, 50.8mm focus
Laser PSU: Reci DY20
Laser tube: ZN-1650 (130W rated power, 150W max, 30mA)

Resources

Access Control

The access control unit will be external to the laser cutter chassis and connected by a cable:

  • GND
  • 5V supply (from laser cutter, always on)
  • Enable power-up (open drain)
  • Current clamp A
  • Current clamp B
  • (additional pins may be required for better active/idle detection)

Monitoring

An external unit will contain an ESP8266 and LCD. It will connect to the main chassis by cable:

  • GND
  • 5V supply (from laser cutter, always on or switched)
  • One wire bus for DS18B20 temperature sensors
  • I2C SDA
  • I2C SCL
  • Laser enable pin
  • Laser power level pin
  • Laser powered-up signal?
  • Laser cutter in use signal?

The monitoring device will:

  • Log laser tube time
  • Log temperatures (ambient, coolant out/return, bed, exhaust)
  • Detect cutting sessions and report the most recent on the LCD
  • Potentially, log fume/particulate levels
lasercutter2.txt · Last modified: 2018-07-19 16:04 by mike