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  1. #1
    Join Date
    Sep 2015
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    Rumpy's Laser Alignment Thread

    Nothing seems to cause more grief and frustration than aligning the laser, so here are some basics to help get you started.

    Laser cutters usually have 3 mirrors, numbered starting at the tube, so Mirror 1 is in the back, closest to the tube, Mirror 2 travels along the Y axis of the Gantry, and Mirror 3 is at the cutting head and travels along the X axis. Mirrors 1 and 2, and sometimes 3 are on adjustable mounts that are used to align the system. They have a pivot point in one corner and two adjustment screws on the back for X and Y. On some, the pivot point is an internal ball bearing, on some it's a short screw on the back, and on others, like the really cheap ones used on a K40, they use the same screws for both pivot and adjustments, which can be confusing. The pivot point is in the middle and should not be adjusted. Also note that the adjustment screws on the K40 adjusters have lock nuts on them which need to be loosened to adjust, then re-tightened so the don't move once set. I really thing replacing the K40 adjusters is one of the best upgrades you can make. My absolute favorites are from Thor Labs, but there's plenty of better options out there for less.

    Now on to alignment:
    First, always work down stream. Start at the laser and work towards the cutting head. Do not move forward until you get each step right, or you'll just end up having to go back and redo everything. Every adjustment you make effects everything after it, so take the time and get it right the first time.

    The system is alignmed when the beam is perfectly parallel to the axis of travel of the gantry. Being "centered on the mirrors" does NOT mean it's alignmed.

    Start with the gantry all the way at the back, closest to the laser, put some tape or whatever in front of Mirror 2 and test fire the laser to make a mark, then move the gartry all the way towards the front, away from the laser and test fire again. See if the dots overlap, if not, use the two adjustment screws on Mirror 1 to move the beam up/down and side to side to overlap them on Mirror 2 in the far-away position. You shouldn't need to turn them very far. After a few tries you'll get a feel for how far. Adjusting the mirror will move the beam a lot far away, and a little up close, so you need to repeat the process a few times to get it dead on. Once they are perfectly overlapped, see where it's hitting on the mirror 2. It do not need to be centered, but if it's too close to the edge, move the whole mirror mount as needed, (usually screws in slots). Make sure everything is exactly as you want it before moving on.

    Once Mirror 1 is correct, place tape in front of Mirror 3, at the entrance of the cutter head and repeat the process. Start with the cutter head closest to Mirror 2, or all the way left on a K40, test fire then move it all the way away from Mirror 2 and test fire again. Adjust Mirror 2 to overlap the spots at the far-away position. Once that is correct, check it with the cutter head all the way away from Mirror 2 in the front and back position. It should stay in alignment in all four corners. If you have three good corners but one is off, Mirror 1 is probably off just a hair. Re-check it and readjust Mirror 2

    Now check to see if the beam is entering the center of the cutter head. If not, move the cutter head with the screws and slots to center it. It's also a good idea to put a piece of tape on the bottom of the cutter to make sure it's coming out centered. Press the tape around the edges of the lens tube to make a mark so you can tell where center is after you remove the tape.

    If you have a larger cutter with an adjustable mount on Mirror 3, remove the lens and place something under the head with the table all the way up, test fire to mark, then lower the table all the way and test fire again. Use the adjustments on Mirror 3 to overlap them in the far-away position, or with the table all the way down.. Replace the lens and that's it!

    Stock Gimbal.jpg
    Last edited by Rumpy; 01-02-2019 at 10:25 PM.



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