Was getting a good beam and testing my new laser cutter when suddenly was not getting any laser beam past the CloudRay “C” style nozzle with 2" lens curved side up.
If I remove the nozzle leaving the rest of the tube coming down from the #3 mirror including the lens and fire a pulse I get a good spot right in the middle of tape placed over the end of the tube.
However, without touching/changing anything except to screw the nozzle back on I get no laser spot coming through the nozzle.
I tried drilling out the nozzle from 2.3mm to 2.8mm but that did not help. Should I continue to enlarge nozzle opening?
And no, there is nothing inside the nozzle, absolutely clean, basically brand new. No air running for the pulse test. If I didn’t need the air assist I suppose I could run without the nozzle but then no air.
Mirror 3 is clean, lens is clean and positioned right way up. Beam is parallel with Z axis but for a stationary test that should not matter. Without moving Z axis, get good spot without nozzle, no beam with nozzle.
To sum, fires fine without nozzle, nothing with nozzle.
It’s a shame you drilled your nozzle. If it is a standard lens and a standard nozzle, then the focal length should fit the hole.
No matter how defective your lens is, a little should come out of the end of the nozzle, it is only when the beam hits the inner sides of the nozzle a lot, nothing comes out, but in return it gets hot.
Are you assuming the lens is defective? It appears to work without the nozzle. I was thinking if the lens was projecting the beam at some odd angle then, ok, it would hit the side of the nozzle.
But, the beam hits the center of tape placed over the tube, so…?
Even if the hole in the nozzle were huge that should not affect the laser firing, only allow more smoke to hit the lens, correct?
I’d take the lens out of the nozzle and replace it with a disk to see where the beam is actually striking with the nozzle assembled. Even though you have done it on the end of the tube.
Really doesn’t make sense, as it’s going somewhere…
How do I know what? That the lens appears to work without the nozzle?
Well, I take the nozzle off, execute a straight line cut across a piece of stock and a burned line appears where you would expect. Don’t know any other way to say it.
Also, if the lens is bad then how can I do the following:
Run the table to its highest point, pulse into some stock (no nozzle) - get a spot.
Run the table all the way down, without touching anything else and fire a second pulse.
It hits the same spot. If the lens were warping the beam to some odd angle how could this happen?
Also, ran some more “cut” lines with the nozzle on and got no cuts. Then took the temp of the nozzle with an infrared thermometer and the nozzle was at room temp.
I know it doesn’t make sense, that’s why I’m here. Normal problems I can usually figure out…
The only thing that’s a mystery is what knocked it out of calibration. I would start the calibration process from mirror 1 and work towards the nozzle opening. In the end I put painters tape on the nozzle tip and kind of rub it on leaving the imprint of the hole. Then test fire in the four bed corners until the beam is in the center of the nozzle, proven by the tape. Each mirror and the nozzle are small challenges that need to be solved. It just takes patience.
According to @jwalkgh , he has done all of that, but there is just no laser beam coming out of the end of the nozzle.
To the best of my knowledge, I can only say that if the laser beam hits mirror no. 3 correctly in all 4 corners of the machine bed, then there is only the possibility left that the laser beam in the nozzle itself is deflected and does not hit the hole. If the lasertube works normally and is “shot” with, for example, 20% power for 10 seconds, then the energy released heats up the nozzle. Energy can not disappear, it only changes its state.
The Z can be perfectly straight, however if it is hitting mirror 3 too high or low, it will cause the beam to hit ‘early’ or ‘late’ and miss the hole.
9 times out of 10 that I have come across this, this is the cause.
Can you try removing the lens and replacing the nozzle to see if you get any output? It may need a few pulses as you don’t have the focusing power, but this will mean the burn mark will be larger so you are more likely to have some pass through the opening.
Hitting mirror 3 too high or too low is the definition of a machine out of alignment.
Sure the lens assembly needs to be at a 45 degree to the lens and normal to work.
Does firing into the side of a nozzle really heat it up? I’d stuff some wood or foam into the nozzle and give it a short burst if you can’t find the beam. If a beam hit mirror 3 then it went somewhere from there.
@jwalkgh, I was thinking of the lens being ‘in’ the nozzle. So the picture in my head was how does he know it works. I envisioned some type of ‘air hook’ …
If I can clarify, from @jwalkgh he has performed these. He has also stated it hits the center of the tape across the lens tube.
He also advises that, with a lens, a spot made at close Z table and a long Z table results in the spots’ being on top of each other. If it is vertically aligned and the beam is in the center of the tube, it has to be missing the nozzles hole.
Doesn’t add up. Which is why @jwalkgh is here asking…
We need to think out of the box here for some kind of diagnostic we can do to help them out. Seems he has a good background, I hate to keep going over the data, the result isn’t going to change.
I have to admit, it has me pretty baffled.
We are missing something… too bad I’m clueless as to what that is
Maybe you need a new nozzle sans the poltergeist option.
A single short pulse will probably not be detectable with a thermometer if it hits the inside of the nozzle, but how is laser energy measured then, it is not the thermal energy that is measured and converted? There is no mystery about this topic other than that we probably do not have all the relevant information for a realistic conclusion. A nozzle is not a black hole that eats energy.
If it’s off enough, it will usually burn though the aluminum anodizing, and reflect around the area. The energy is going somewhere… as @bernd.dk points out.
This is indicative of a hardware failure in the optical path, since we now know that it has maintained the alignment.
@jwalkgh have you put a piece of tape over the nozzle and see if there is anything right at the end of the nozzle…?
I’ve got to try to “catch” the beam inside the nozzle since that is the failure point.
I get a good sharp beam without it and no beam with it so …
I will try with the tube and nozzle but no lens. I have tried with no tube at all - coming straight down from mirror 3 - and that works fine.
I will try to either a) fabricate/3D print a nozzle substitute that will easily deform or otherwise indicate where the beam is going or b) line the nozzle with tape or other to get some indication that way.
Obviously not too keen on starting from scratch but I do love the smell of burnt masking tape in the morning :>).
It will not work, your laser beam is too large in diameter, you should not do it.
Have you tried to check your nozzle if it is vertical, on both sides at 90 degrees to your frame / machine bed ?, this is where it typically goes wrong.
I once tried printing a nozzle but since my printer doesn’t have the resolution to make a 22mm thread, I couldn’t get it to mount properly.
The beam will slice thru the nozzle but if you can’t guarantee position, not sure how that helps.
Dean, that’s exactly what I want to happen.
Just downloaded an STL file for a nozzle with NO exit hole.
It will force an exit and then I’ll know for sure if we’re getting a beam and where it’s going.
Potential fire starter not withstanding.
If you still wanted to explore this you could probably increase wall thickness where the threads are supposed to be and use a thread cutter to cut the threads.
