In this series we'll be explaining how to align the laser mirrors on your Vertical Laser XL machine. Note that these techniques can also be used for alignment on the blackTooth laser cutter and engraver.
In this video we’re going to demonstrate how to align the mirrors on the Vertical Laser XL. The Vertical Laser XL is a 4’ x 8’ vertically-oriented lasing and engraving machine.
Disclaimer: These tasks are potentially dangerous and proper caution should be exercised. Always use appropriate safety gear and have a fire extinguisher nearby no matter what laser machine you are using. If you decide to follow these instructions, please do so at your own risk. If you do not feel comfortable performing these tasks, seek professional assistance.
The tasks involved with aligning the Vertical Laser XL involve aligning three mirrors. One mirror will be reflecting the laser energy from the laser tube. Since the tube is riding on the gantry, you only have to align the laser on one main axis. The other two mirrors will be static and not move in relation to the laser tube. The third mirror is on the nozzle and this is the one that moves.
On a traditional laser cutter and engraver, you actually have two mirrors that move because the gantry has to move away from the laser tube. This means having to align mirrors on two axes which is far more complicated. In these tasks, you will find that the laser aligning is quite straight-forward.
We’ll start with the first mirror that is reflecting the laser energy directly from the laser tube. You can use these techniques with traditional laser cutters in which the tube is stationary, but remember you will have to do this on two axes and when you get to the final axis, make sure that the first mirror (that reflects the initial energy) is very well aligned so that there will be minimal diversion when aligning the final mirror on the nozzle.
The parts we will be working on specifically on the Vertical Laser XL will be where the tube aligns with the mirror. In the video you can see where the two mirrors are aligned toward the bottom of the gantry and then reflect up to the mirror that is on the nozzle which is stationed on the gantry. Before we test, we need to make sure the motors and controller are turned on.
When we first turn on the controller, the gantry will automatically try to find it’s home position. We are going to jog the gantry from the laser controller using the left and right arrows to position the gantry in the best way to perform the alignment.
We’ll start the alignment from the tube to the first mirror. What we want to know is where the laser is hitting the first mirror. You have an adjustment here on the first mirror with a hex bolt so it can be adjusted easily. We’re going to put a piece of tape on the mirror and pulse the laser very quickly so we can see where the dot hits in the area. We want it to hit as close to the center as possible.
Now before we fire the laser, we will remove the mirror for safety, as the laser could bounce off the mirror and pose a safety threat. When you’re taking the mirror out, it will not affect the angle. There is a nut that keeps the mirror in place. Place the mirror on a surface that won’t scratch it. Now we’ll see if the beam can pass through any part of this. Make sure it cannot pass through and damage anything.
In this video we’re using a non-reflective paving stone between the ribs and then we move the gantry to position it over the stone to make sure it is safe in case any of the beam passes through. Now we’re going to apply masking tape.
CAUTION: Take great care when using masking tape. Masking tape can ignite and burn very easily. When you pulse the laser, be ready to take action to extinguish a flame if one does form. Have a fire extinguisher close by just in case! A primed and inspected fire extinguisher should always be near laser equipment.
Run your finger on the masking tape around the edge of the circle so you can tell where it is. Before you turn on the laser make sure there is water circulating in the tube and the power supply is on.
Press the laser button just for a second until you see a mark on the masking tape. If the mark was in the center, then your mirror is aligned. If it is to the left or the right, you will need to adjust the mirror accordingly. Since we have a good marking we’ll reinstall the mirror. The silver side is the back of the mirror. Insert the correct way and then put the set screw back. You can also put an o-ring to get a better hold between the nut and mirror.
Now you will want to make sure the angles of the mirror mounts are correct. You can take a cell phone camera and view the nozzle through the camera on a smart phone.
It is important to note that just because the end of the laser tube is visible within both mirrors does not mean that the beam will travel along that part. If the tube from end to end is not aligned (meaning the back of the laser tube is also viewable in the mirrors, which cannot be seen) then the beam will not hit the expected target.
We’re going to next remove the next mirror and apply masking tape and do the same test as with the previous mirror. Be sure to again install something to absorb any laser energy.
Also note that your mirrors should be cleaned regularly. Use a q-tip and some alcohol to clean the mirrors. Apply some alcohol to the mirror and gently rub it onto the mirror lens to remove any residue or debris. Then clean the mirror with a non-abrasive cloth.
In Part 2, we will continue aligning the 2nd mirror and explain how to use the screws that are used for the minor adjustments. In Part 1 we discussed the specific configuration of the mirrors in relation to the tube and we fired the laser and demonstrated how to clean the mirror.
Now we will continue with putting back the mirror holder and fastening it back onto the mirror mount. Remember again: These tasks can potentially be dangerous. Proceed at your own risk. Please seek professional help if you are not comfortable doing any of these tasks.
We’re going to put the mirror mount back into place and put a piece of masking tape over the circle as we did before. Go around the edge with your finger again to get an idea where the edges are. Now fire the laser, remembering to take all safety precautions.
We’ve fired the laser and we can see that we did get it between the circle, but it isn’t quite centered. We need to adjust the mount to align the mirror.
When you’re adjusting the lens position, first you can see the mounting hole and how it is mounted on the machine. There are two large screws on the mount that are very apparent, but there are also smaller screws. The reason is some of the screws are for tension and others for adjustment. The way we need to bring the adjustment in is to tighten the small screw. You may have to adjust both screws because one acts as a nut and one acts as a screw.
Now we’ve moved the frame in. Let’s now talk about how to move the frame out. The video illustrates which way the laser will fire as you adjust the mirror holder. You will see how the large screw is adjusted and the small screw is loosened to move the frame out. Remember not to unscrew so far as to where the screw comes completely out.
We want the beam to move up to align it correctly, so we’re going to loosen the large screw just a little bit and tighten the small screw underneath it. Once we’ve done this we fire the laser again to see what happens.
In the video you’ll see the masking tape caught on fire during the initial firing, which meant we had to do the test again. On the second firing the location of the beam is now satisfactory, so we put the mirror back on. The 2nd mirror is now aligned.
In the last 2 parts we aligned two mirror mounts. In this third and final part we will be aligning the final mirror on the nozzle and then doing a test cut to see how everything is working.
We’re first going to move the nozzle down toward the mirror. The laser needs to be able to hit the center directly. We will again be using masking tape for this test so remember to always have a fire extinguisher on hand. We’re going to leave the mirror on this time since it won’t damage anything or pose a safety threat if the alignment is off.
We’ll start from the very bottom and apply masking tape. If the beam hits anywhere outside of the hole, we’ll know with a level of certainty where we’ll need to adjust. In the video demonstration we see the laser hit mostly in the center, maybe slightly low. We also need to make sure the laser is in a straight line, so we raise the nozzle up and fire again. We took a photo of the position at each test to compare and see if the laser was still firing in the same place.
After the latest test we found that the alignment was slightly to the right, so we need to adjust the mirror inward. Using the loosen/tighten technique we adjust the mirror mount inward. After another test we found that it was too far to the left, so we went too far on the adjustment.
Once we adjusted again, we had it centered but it was still a little too far right. It is recommended that you keep doing this process at the bottom, middle, and top of the gantry position so you know you have perfect alignment in a straight line.
Once the process is done we know that the laser is centered along the top, middle, and bottom points. The next thing we need to do is make sure the mirror is going to hit the lens at the center of its’ opening. We’re going to take the assembly off and using tape once more. Tighten and loosen the screw on the mount on the nozzle like you did with the other mounts. It may seem counterintuitive, but trust the process.
Now we’re ready to align the lens at different levels. In the video you can see that we had perfect alignment on the bottom and middle tests. The high test yielded a bit of a high result, so we adjust the mount slightly to bring it down a little bit. We adjusted it a 2nd time to make sure it was aligned well in the center. Next we needed to make sure it was still centered on the bottom and middle levels as well.
After tweaking the alignment in multiple positions, we found we had perfect alignment on all three points, so we put the assembly back together. At this point we were ready to do a test cut with the machine. We calibrated the distance between the nozzle and the material first.
Once we were all set up, we ran a test to make sure the nozzle would run in a box confined to the material. At this point the machine is ready to go to work.
To remove smoke, dust, and eliminate flare ups, we are using an industrial dust extractor at one end of the machine and a compressor to produce a high flow of focused air through the nozzle aperature.