Laser Cutter Cleaning

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Cleaning the Laser Cutter

When it comes to the Trogdor the laser cutter there are four kinds of cleaning:

1) Basic cleaning up after yourself every time you use the laser cutter.

2) Maintenance cleaning every time you use the laser cutter for a large job.

3) Routine maintenance cleaning, which is everybody's job.

4) Special maintenance cleaning inside the laser cutter and of the laser tube, which should be done only rarely and by members speically trained to do so.

Note: For safetey reasons DO NOT access the interior of the laser cutter (i.e. any panel which has a lock, really just anything inside the laser cutter except for the cutting area) without special training.

Warning Signs To Watch Out For

Your first thought on seeing any warning signs are to a) shut off the laser cutter and evaluate, b) make sure you have the exhaust blower fan turned on and functioning properly.

Watch out for these warning signs:

  1. excessive smoke in general may indicate
  2. smeared burns or poor cutting performance
  3. visible smoke rising from the cut point rather than being sucked away underneath
  4. brighter light from the cut point
  5. frequent orange sparks

If you see any of these warning signs you should stop and take appropriate actions, as continuing to cut with these warning signs may lead to further degradation of the laser cutting performance, even possibly damage to the laser cutter or, most importantly, safety risks.

Note: Smoke accumulation on the lense not only interferes with the cutting performance, it causes heat buildup which can eventually permanently ruin the lense. Each lense costs around $50.

Excessive smoke resulting from proper (see power setting notes below) of the laser cutter may indicate that the exhaust system is not operating properly. The most obvious (and easiest) things to check are, in ascending order of difficulty the vent on the exhaust blower fan, the vent inside the laser cutter leading to the exhaust blower fan, the internals of the exhaust blower fan, and the internals of the ventilation duct.

Smeared burns or poor cutting performance may indicate a dirty lense, or may indicate that you need to re-do the laser focusing (Z-registering, aka checking the laser height/focus with the height gauge).

For Z-registering the laser height/focus, refer to your laser cutter training.

For cleaning the vents and lense, see below.

For the internals of the exhaust blower fan and ventilation duct, stop using the laser cutter and contact the board (use the @board tag on the HackPgh slackchat). Do not use the laser cutter until the problems have been addressed.

Power Setting Warning Signs

Visible smoke rising up (not down) from the cut point, brighter light at the cut point, or frequent orange sparks being thrown off from the cut point can all indicate a problem with cutting, usually related to power

If all else is proper, these are usually symptoms of the laser not cutting all the way through. You need to adjust your power and speed, or you need to reconsider if your material is appropriate for cutting in the laser cutter.

Too much power/too low speed can also be a problem, it can cause too much smoke generation, which then interferes with the cutting action. 60-70 power seems to be the sweet spot for most general use with thin (around 1/4") plywood.

Adjusting power and speed is outside the scope of this document. Hopefully someday we'll have more info on that and will link to it from here.

Basic Cleaning Up After Yourself

Important Note: Keep the laser cutter lid closed at all times other than when you need to open it. Even with the exhaust system, leaving the lid open allows extremely fine particles into the shop air, which can cause immediate allergy reactions from some members, and in the long run, like any super fine wood dust, can have serious health implications.

Every time you use the laser cutter you should clean up after yourself. Mostly this means making sure you don't leave any bits of wood on the bed of the laser cutter and making sure you dispose of your laser cutter scraps properly, instead of leaving them lying around.

There is a little gray and yellow shopvac that is supposed to be kept near the laser cutter, for vaccuuming up the small (1/2" square or smaller) bits of wood that often result from a laser cutting. Obviously, after using the small shopvac you should consider whether or not it needs to be emptied. A good rule of thumb is that if it is near half full, empty it.

Maintenance Cleaning After A Large Laser Cutting Job

Any time you use the laser for an hour or more of cutting, you should check the exhaust system to make sure that it is not clogged up. Generally speaking you should not often need to actually clean it for only an hour of usage, but check every time, and if necessary clean. See below.

Routine Maintenance Cleaning Is Everybody's Job

Remember, HackPgh has no employees, we're a member-driven, member-operated makerspace. The more you use the laser cutter the more you should take on the responsibility for maintenance, not just cleaning up after yourself but occasionally volunteering to do maintenance (and mentoring other members in both).

If you're new at it, don't hesitate to ask other members for help. If you're experienced at it, don't just do the job for somebody else, help them learn to do it themselves.

Routine maintenance should be done at least once every 2-3 hours of laser cutting time. This includes checking and if necessary clearing the exhaust vents on the exhaust blower fan and inside the laser cutter, and checking and if necessary cleaning the lense.

Cleaning the Exhaust System

Remove Sound Muffling Box

Step one is to remove the big cardboard sound muffling box that covers the big, pale green exhaust blower fan.

Note that the sound muffling box has two cutouts for exhaust vent hoses. When you put the box back in place, the larger cutout should face towards the laser cutter.

Remove Band Clamp and Detach Blue Vent Hose

The band clamp is a glorified hose clamp that fastens the blue vent hose from the laser cutter to the exhaust blower fan.

You can loosen the band clamp with a large flat-head screwdriver, or with a 6mm ratchet wrench.

Then pull the blue vent hose off the big green blower.

Check the evacuation grill on the side of the blower. Wipe it down with a paper towel to remove any obstructions.

Reattach the blue vent hose -- note that the hose goes over the metal rim around the evacuation grill -- and put the band clamp back in place and tighten it.

Don't go overboard on tightening the band clamp, while using a 6mm ratchet wrench to remove the band clamp is ``easier`` it should not be ``necessary``.

Replace the Sound Muffling Box

Make sure the larger vent hose cutout is facing towards the laser cutter.

Check the Laser Cutter Internal Exhaust Vent

Remove the honeycomb on the bed of the laser cutter. Just lift it up and slide it out. It's pretty tough but handle it carefully, don't bang it around.

Also, be aware the honeycomb and the supports under it may be a bit sooty.

Look at the vent aperture under the horizontal supports.

There is no easy way to remove the horizontal supports, so if the aperture needs to be cleaned, just use a stick or long-handled stick brush. There should be a long-handled brush on the small table adjacent to the laser cutter, for this purpose.

You've Cleaned The Vents and Still Get Smoke

If you're still getting excess smoke, there may be an obstruction inside either the blower or the ventilation duct.

Stop using the laser cutter and contact the board via the @board tag on the HackPGH slackchat.

The blower may need a complete teardown and rebuilt to clear an obstruction inside the fan area. For safety reasons this must be done only by members with special training for this task.

If the blower has been torn down and you're still getting excess smoke, there may be an obstruction inside the ventilation duct. This is something that must be addressed by the landlord.

Lense Cleaning

The lense may need to be cleaned after 2-3 hours of cutting time, or after a shorter period of excessive smoke. Note, this is one of the reasons you should not continue using the laser cutter if you see excessive smoke.

The lense costs around $50 and is a little more fragile than glass. Also, the lense is more easily scratched than glass, so proper cleaning technique is important.

After removing the lense holder and laser nozzle (see below), carefully move the lense holder and laser nozzle to a wide, uncluttered table with good lighting for further work, to decrease risk of dropping it or otherwise damaging it.

TODO: INSERT PHOTO OF LASER TUBE/NOZZLE WITH LABELS

Removing the Lense Holder and Laser Nozzle From The Laser Cutter

Lower the Z tray several inches to give you room to work.

Gently loosen the collar on the lense holder tube. You shouldn't need to exert significant force to get it to loosen. If you do need significant force, somebody reinstalled it improperly. Stop and contact the board for further help.

Once you have the collar loosened, unscrew the brass fitting that connects the air assist hose to the nozzle.

Unplug the position laser pointer wire from the top of the lense holding tube.

TODO: Need to insert note here about the two pointer wires and how to figure out which is which. We should also mark the pointer wire jacks with paint or something.

TODO: What's the word/phrase for the entire assembly? Cutting head?

Remove the laser tube assembly (lense holder tube and laser nozzle) from the cutting head.

Loosen the brass set screw on the side of the lense holding tube to allow the laser nozzle to be removed.

Remove the laser nozzle from the lense holding tube.

Cleaning Supplies

There is a cleaning kit in a small clear plastic bin with blue handle, it should be on the small table next to the laser cutter, behind the monitor.

For a cleaning solvent, isopropyl alcohol or white vinegar are suitable.

A small spray bottle of isopropyl alcohol may be in the cleaning kit, or it may have been stored in the flammables locker, the yellow metal locker between the welding table and the metal working area.

White vinegar is also a suitable cleanser and should be on the table adjacent to the laser cutter. If not there, a member may have stored it in the kitchen area. Look in the supply lockers or on the shelves in/near the kitchen.

You may find it useful to get a small disposable dish, plate, cup or bowl from the kitchen area to hold a little alcohol or white vinegar during the cleaning.

You should also use a plate or other shallow container if you disassemble the lense tube (see below), to keep the various small parts from being lost or misplaced.

Cleaning the Lense

For most cleaning, you should be able to simply clean the lense while it is still installed in the lense holder tube.

TODO: How do you diagnose when the lense requires removal?

The cleaning kit should contain either q-tips and a bundle of cotton. Use either, but the following will be written assuming you're using the cotton.

Pour a bit of isopropyl alcohol or vinegar into a small dish of some sort. While cleaning you'll be holding the lense with one hand and the cotton or q-tip with the other, so having the cleaning solution in a dish will be easier.

Pull off a small ball of cleaning cotton, about 1/4" diameter, or slightly larger or smaller depending on what you find easiest to hold.

Dip the cotton ball in the cleaning solution.

TOUCH (do not press) the wet part of the cotton ball against the center of the lense.

Simultaneously rotate the ball outwards, i.e. away from the center of the lense, as you brush the ball from the center towards the edge. It is important to to do this so you do not grind the grit from the smoke on the lense as you brush. Instead you want to continuously rotate as you move the ball, so a clean bit of cotton and cleaning solution is applied to the lense throughout the entire movement.

Discard the ball after one brush. You never want to rub a dirty cotton ball or q-tip against the lense. If you even suspect it's dirty, discard the cotton ball and get a new one. Cotton is cheap, lenses cost $50.

Repeat the process, rotating the lense and lense holder slightly, until you've wiped down the entire lense surface.

When you've cleaned the entire lense, inspect it carefully for any stray fibers or bits of fuzz, before reinstalling it.

Cleaning the Laser Nozzle

Wipe down the laser nozzle with a paper towel dipped in vinegar to remove any soot from it.

Reinstalling the Laser Nozzle on the Lense holder

Hold the lense holder tube with the end with the lense facing up.

Set the laser nozzle on top of the lense holding tube.

Make sure the lense holder tube and laser nozzle are rotated so that the hole for the brass set screw hole is on the opposite side from the position laser pointer.

Reinsert the brass set screw and gently tighten it by finger to hold the laser nozzle onto the lense holder tube.

Tighten the brass set screw by finger, then carefully use a piar of pliers to tighten it one half a turn further.

Reinstalling the Lense Holder and Laser Nozzle into the Laser

Insert the reassembled lense holder tube and laser nozzle into the laser cutter head fixture until about 1 inch of lense holder tube shows between the collar and the nozzle.

Check to make sure that the tip of the laser nozzle will clear the platform edge. If not, reduce the amount of lense holder tube visible between the collar and the laser nozzle until it will.

Finger tighten the collar - snug, but not tight. Tug on the tube; if it doesn't slide, the collar is tight enough.

Reconnect the position laser pointer.

TODO: Insert note about two position laser pointer connectors and how to tell the difference.

Reconnect the air assist hose. Before attaching the brass fitting of the hose, twist the fitting backwards about 5 times, so that as you tighten the brass fitting, the hose will unwind until it is fully untwisted. "Backwards" means in the opposite direection that the brass fitting is threaded, which you can determine checking the fitting.

TODO: Check on "backwards" this and insert direction above.

Check your reinstall by holding a piece of wood under the nozzle and confirming that you see a laser dot on the peice of wood, in the appropriate location.

Removing the Lense from the Lense Holder

Generally you do not need to disassemble the lense from the lense holder -- unless somebody either spent way too long using the laser cutter with too much smoke, or made some other major mistake and the lense is very, very dirty.

TODO: Should take or find some photos of clean, clean-without-removing and need-to-remove lenses.

Note: Smoke accumulation on the lense not only interferes with the cutting performance, it causes heat buildup which can eventually permanently ruin the lense. Each lense costs around $50.

If you need to remove the lense from the lense holder tube, use the following instructions, then carefully hold the lense by the edges and clean as in the instructions above.

Get a plate or other shallow container to keep the small parts of the lense holder organized as you work, to avoid losing or misplacing them.

The lense is inset about half an inch from one end of the lense holder tube. A metal retaining ring inside the tube holds the lense in place, and under the metal collar, between the collar and the lense, is a pale rubber O ring.

TODO: which term is better, retaining collar or retaining ring? Going with ring for now, to disambiguate from the black plastic collar that holds the lense holder tube into the laser cutter head fixture.

TODO: Find or make a cutaway diagram of tube, lense, O ring, ring.

The metal retaining ring has a set of two notches on opposite sides. The lense removal tool looks like a rectantular piece of metal just wide enough to fit into the tube and into those notches, about 3 inches long.

Carefully insert the lense removal tool into the tube, into the notches in the retaining ring.

Gently twist the lense removal tool counterclockwise (left is loose).

TODO: IMPORTANT, confirm counterclockwise for retaining ring removal?

Remove the lense removal tool and set aside.

Carefully shake the retaining ring out into your palm and set on your parts plate.

Find a piece of relatively soft plastic to pry up the pale rubber O ring that was under the retaining ring. For example break a q-tip in half and use that. The lense is glass-like but is actually softer than glass and easier to scratch.

Remove O ring and set on your parts plate.

Carefully shake the lense out of the lense holder tube into your palm. Set the lense holder tube on your parts plate.

Clean the lense as described above.

Reinserting the Lense in the Lense Holder

There are three lenses currently in use. All of them have a convex side.

The lense goes into the lense holder tube with the convex side of the lense facing towards the longer part of the lense holder tube, i.e. facing away from the laser nozzle, so that after you reinstall the laser nozzle and you reinstall the entire thing in the laser cutter, the not-convex side of the lense will be facing towards the bed of the laser cutter.

TODO: Find or make a simple diagram for convex side, etc. (Or re-use the cutaway diagram from above)

Reinsert the pale rubber O ring on top of the lense.

Reinsert the metal retaining ring, notches facing out towards the open end of the tube, away from the lense.

Use the lense removal tool to turn the metal retaining ring about 2.5 turns STOP turning when the ring gives you any resistance. Turn too hard and you can break the $50 lense.

Now you're ready to reattach the laser nozzle, see above.