It’s always been like this. Having said that, I’ve never really cut a lot of material that would span my honeycomb bed. I usually just do coasters or tumblers and other small pieces on the CO2. Never got into the larger work.
I thought I would create a board for a local restaurant down the road from me. I think it’s like 4" tall x 13" wide. The piece is located top left of the bed looking down at it.
I’m running my stock 2" lens. The only lens that I have BTW. I masked off the piece, got it centered, and ran it. Fairly deep engrave on the left side, and almost nothing to the right side of the piece. Didn’t even burn the tape mask.
So I figure let me do a tape burn test to start off. This tape was on mirror 3. I moved the gantry to the left over the piece, and pulsed. Then I moved it to the right side of the piece and pulsed. You can see the difference. Both dots are really close to being in the middle of the mirror even though you can’t see the impression of the opening of the mirror.
The piece was really close to being level to the head using some shim stock under the right side of it to get to that point. Is that difference between the dots enough to warrant that much deuteriation of my burn across the piece? If so, do I just mess with mirror 2 to get them closer or on top of each other, or should I be looking elsewhere?
Unfortunately, there is no such thing as “almost” or “reasonably” accurate when it comes to laser beam alignment. If it were me, I would start all over again and find out why and where the error lies. Find some good videos that deal with laser beam alignment to find out how it should be done.
Expanding the hole in the nozzle - is a bad idea and definitely not the right way to solve your problem. But the nozzle is part of the problem if it doesn’t point 100% correctly straight down.
Does the beam hit the center of all three mirrors?
That requires checking at the surface of the mirror, not just the entrance aperture, because the holder can be rotated enough to make the obvious test come out wrong. This was on Mirror 2 with the beam in the middle of the entrance aperture:
I agree that you need to take time to align the machine. I’ll do that even if I clean mirrors but I found a fast method, so it’s not a big deal.
One easy way to see if it’s out of alignment is to rub in tape on the end of the nozzle and test fire. You should see the outline of the nozzle opening and the beam at each bed location. Obviously retape each time you move to a new location.
Also agree that you don’t open the hole in the nozzle because that affects air flow.
If you’re watching videos, check out Russ Sadler site. This is a good one on alignment. Might not be an identical machine, but the alignment process is the same. You might not have some of these adjustments but you can figure that out.
This is one of his tools for checking the beam at the nozzle…
Well, we have some progress. I did watch the vids too.
I knew something was up when I was just making some 4" x-mas ornaments, and I wasn’t getting a clean cut on the right side -vs- the left side. Didn’t surprise me though. I’ve never worked across the whole bed with large pieces.
Did some shim work on the right side of the bed rails. Made some targets, and got things really close. At least better than before I started with regard to the bed being level to the head.
I burned a stripe across this piece of pine before starting this alignment stuff.
As you can see at the beginning nothing, then a burn, then a deep burn, then off to nothing land.
The last mark is where I’m at this a.m. I’ll settle for this for now. Cleaned all my mirrors too while I was at it. I had to make some more ornaments this weekend, and had to adjust some power / speed settings after all this…
Jack! What the heck are you talking about? That’s all greek to me. I’m just an old redneck in the middle of the sticks… LOL
I did find this.
The TEM00 mode is the lowest-order transverse mode . It has the lowest threshold, smallest beam waist and divergence, and contains no nodes in the output beam transverse intensity distribution.
On the Russ video. Never put your hands in a working laser. That’s just unsafe and why they come with safety lids. I got nicked by an invisible beam once and it’s extremely fast and painful
On his point at 45 about loss of power the farther the beam travels. I understand what he’s talking about but I would assume that maintaining alignment in large machines is a bigger problem then loss of power. Mine is about the size of his and I’m not bothered by that. Maybe he has a lower wattage machine.
In both of your statements, I will give you, from my own experience, right. You shouldn’t have your fingers in the machine room and the loss of effect after one meter with a 60 Watt CO2 laser is significantly less than a laser beam that is 1mm off center.
I’m quite a bit better off today, than I was last week before making targets, mirror alignment, and leveling the honeycomb bed to the laser head. At least now 9" away from the left side I can get the same depth all away across.
I’m pretty sure I won’t be making anything large to cover the entire bed of the machine, but still it’s nice to get this far. Before I really knew anything about the laser and what it does, I cut my laser pointer wire in half with it…
I think it is fairly important that the laser cuts evenly over the entire work area. When I order material it is 600x400 mm and I need the entire area, not just for small parts. Eg. Ikea sells coconut door mats at a fair price, I “decorate, personify” them individually and sell them. The mats are exactly 600x400 mm ;-), - no possibility and no desire to turn them during processing.
Keep finding the optimal setting, you will be rewarded in the end.
