Laser Cutter/Full Spectrum Laser 40W/Unofficial Manual

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hi, hope you don't mind me abusing your wiki a little.. I own a FS laser, many hacker spaces seem to as well.. and there are a lot of tips scattered around as well as the official manual.. but i found in using these sources i never had one good reference for common issues.. i hope to steal heavily from these sources and compile them into one document that is not on a moderated bulletin board.. I'm planning on working on this over time.. i hope its not a total wreck when you find it ;)

I know there are no images now, i intend to take some as to not steal directly from FS laser's actual manual.


.. i should probably have something here.. but safety third i suppose

Preventative Maintenance[edit]

Water Reservoir[edit]

check that your water bucket and hoses with your hands, make sure there isn't any slippery biofilms, or obvious alge issues, you can prevent and treat these issues using _*EITHER*_ a small amount of hydrogen peroxide, or a small amount of bleach.. in either case exposure to the laser will eventually degrade these chemicals so they will need to be checked and replaced periodically.

Its also good to make sure that your water bucket is full.. running your laser without water moving through it can shorten the life dramatically. not to mention preventing "catastrophic failure" of the laser tube.

If your bucket has a crusty film marking where the waterline previously was (due to loss from evaporation) consider rinsing the laser with distilled water and and a small amount of vinegar; rinse with distilled water; then replace the reservoir water with clean distilled water.

Also, run your water for about 30 minutes after you are finished cutting with your laser, to ensure that it is sufficiently cooled and to prolong the laser tube's life.

Rails and Bearings[edit]

Probably need something in here, what is the best type of lubricant to use?

Aligning Your Laser[edit]

(this procedure is mostly the same as documented by fslaser)

Vertical alignment[edit]

remove the lens from the carriage head and replace it with thermal paper as was used in previous alignment steps, ensure that the test fire pattern of the laser hits the middle of the hole where the lens would be; the darkened paper image should have no half-moon shaped, non-darkened areas.. if this is the case your angled mirror will need to be shimmed before you will get decent cuts.

Laser Power Settings[edit]

Tightening Your Laser[edit]

Laser Head[edit]

The laserhead has 4 plastic wheels. These attach to an eccentric pin through a small Phillips (crosshead) screw. If you rotate these eccentric pins then it will tighten or loosen against the aluminum X axis rail. These eccentric pins are held in position by a set screw with a hex head 90degrees from the top Philips screw. Remove the setscrew before attempting to adjust the eccentric pins. The eccentric pins need to be adjusted by inserting an extremely short FLAT head screwdriver through the BOTTOM. If you adjust the crosshead screw from on top it will have extremely limited motion for adjustment. Tighten the top crosshead screw then do all further adjustments from the bottom. To remove the pins, turn from the bottom to loosen then push from the bottom to remove.

  1. Loosen the 4 eccentric pins by using the short screwdriver from the bottom. The laserhead will not be clamped to the X axis gantry anymore.
  2. Adjust the top 2 eccentric screws so they that the laserhead is straight with the X axis. Since they are eccentric you want the laserhead platform straight otherwise the belt will be pulled at a angle.
  3. Adjust the bottom 2 eccentric screws so that the laserhead is as loose as possible but all 4 wheels are just barely still rolling.
  4. Insert the 4x set screws with the hex heads back and tighten. Note that by putting the set screws back in it will tighten the eccentric pins slightly so that is why we say adjust as loose as possible but still rolling in step 3.
  5. Test it out and ensure the X axis is not binding during rastering. If you would like you can insert some WEAK thread locking glue on the screws.


In some cases, the belt tension might need adjustment on initial receipt. Movement should be smooth and not grainy or overly difficult. If the laser engraves at lower speed but at 100% speed the laser seems to jerk or stall, the belt tension should be loosened. If engraving lines do not appear straight, the belt tension should probably be increased. Adjust the bolts shown in the picture with a 3mm hex key. Purchase a long hex key and there is an access hole on the right hand side of the machine. Turning clockwise increases the belt tension.


To tighten the Y-Axis you may need a special long handled allen wrench unless you have exceptionally long allen keys. to the rear of the laser there are two round holes on either side located roughly where the belt tensioning mechanicanism is located; you must adjust the belts on both sides to the same tension as any difference in tension will cause the engraver to "parallelogram" jobs.


While its not mentioned anywhere.. the lens in the hobby laser is essentially free floating, cushioned only by a rubber washer in the head, this can cause problems in the print quality later if the lens doesn't settle flat; or if the lens wiggles due to vibration during cutting. The method i used to solve this was to make an ABS glue using acetone and small chunks of natural colored ABS feedstock from my makerbot which resulted in a thin white glue. Using three very small dabs around the perimeter of the lens was more then enough to hold the lens in place.. and daily breaks away from both the metal and the glass lens when its time to replace them.

Focusing Your Laser[edit]

Changing The Laser Tube[edit]

On my 40-watt hobby laser, I noticed that the laser beam was losing power, and engravings that used to be darker were now very light to almost nonexistent at the same power settings. I also heard what sounded like electricity arcing (a buzzing sound) somewhere in the machine when I test-fired the laser, which, while being a vary bad thing, also indicated that power was not going through the tube, but bypassing it. (If you hear an arcing sound, do not press the test button anymore, because, if you haven't done it already, you will most likely fry the USB circuit board, among other things, which is exactly what I did.)

Rather than spend $300 on a 40-watt CO2 tube from the company, I bought the exact same tube on ebay from china for less than half the price. It arrived at my house in about a week or so.

To change the tube, I first unplugged the machine (make sure to do this) and carefully took off all of the cooling water hoses, noting exactly where they attached to the old tube. Next, I cut the wires connecting the machine to the old tube. After loosening the straps holding the tube to the machine, I lifted it out, and replaced it with the new tube, making sure not to touch the beam-emitting end of the tube. Next, I cleaned the terminals and stripped the wire-ends, so that fresh wire was exposed. Before twisting the wire around the terminals, I slipped a piece of silicone tubing over the wires, so that, after I attached the wires to the terminals, I would be able to pull the silicone tubing back over the exposed connections. Heat-shrink tubing will also work in a similar way.

NOTE: It may be necessary to connect the new tube outside of the machine, due to the lack of working room for one's hands inside.

There is more than one way to connect your terminal-ends to the wiring. The best way is to solder these connections. Soldered connections don't become weak with oxidation. The main problem is that the terminals are very thick, and difficult to heat up sufficiently with a soldering iron. There is also the possibility of overheating the terminal and cracking the glass tube, which would be no fun.

To solder the connections, you will need something that can really heat up the ends, so that the solder, with the help of some flux, will stick to the terminals and fuse to the wire, causing a bond. I went the quick and dirty way and wrapped my wires around the clean terminals, then pulled the heat-shrink tubing over them, which I then shrank with a lighter. After this, I pulled the silicone tubing over the heat-shrink tubing and temporarily taped the silicone tubing in place onto the laser-tube before filling the silicone tubing with 100% silicone caulk around the connection as an added insulator and as an adhesive. My goal was to keep the connections from oxidizing over time and to insulate them so that electricity didn't arc to the body of the machine when the current ran through the connections. After letting this dry, I re-attached the water tubes to the proper nipples, and tested my tube, which is still working fine, several months later.

There is some possibility that you will need to realign your beam. Before adjusting your mirrors, I recommend that you re-position your tube into the same place that the old one was before, which should line it up correctly with your mirrors, since they were already lined up with your old tube.

Quality Testing Procedures[edit]

Raster Speed and Alignment[edit]

Raster engraving QR codes at full speed and low power into wood or cardboard can be used to test how well the head is positioning itself. To perform this test:

  1. download SVG file and print it using Inkscape
  2. print at a low enough power not to burn the test material, but enough to brown; but be sure to print at 100% speed.
  3. check the alignment of the laser engraver by looking at the finished engraving along the edge's a well aligned laser head will have perfectly straight lines along both dimensions;
  4. if you have any wobble, or wondering in the test pattern, adjust your X and Y belt tension, in general tighter is better

Cutting Times[edit]

Trouble Shooting[edit]

Cut lines do not overlap perfectly on repeats when cutting through thick material[edit]

check the X and Y platform belt tension, belts should be taut but not tight like a guitar string (it should not vibrate when plucked) this is the easiest and most likely cause.

Also check the head alignment, if the head itself isn't tight agains the track it can cause some backlash (wiggle) in the head position as the belt changes direction.

check that your lens is firmly in place and not actually vibrating in the lens holder.. a vibrating lens can easily be the cause of ugly and misaligned cuts.

Head thrashes during a raster engrave, seems to get stuck causing the belt to slip and buzz[edit]

the laser head is binding, there can really only be two causes for this issue, either the laser head (carriage) is binding because the X-axis belt is too lose, or the carriage itself is not aligned, or is lose on the track, to fix this see "aligning the laser".

The engraver turns lights on but no longer cuts anything[edit]

Sometimes the engraver can blow a fuse and there is no indicator to tell you that it has occurred.. there is also no real mention on where the fuse is.. but this is the most likely cause of this problem.. if changing the fuse does not fix the problem, or the fuse blows again immediately after installation you probably have a bad power supply.. tough luck.