Using the latest version of LB. 80W Co2 OMTech laser.
The quality of burn seems to change during the burn.
I always do sample burn on a scrap piece or waste corner of my workpiece until I am satisfied with the result. However when I do the final it is different than the test.
Attached please see attached attempted through burn Laser set to 10.2/sec @ 80% min & 80% max. The workpiece had a slight bow in the middle and was fastened flat.
1st pic is the top
2nd pic is the underside - notice 1 vector was 100%, 1 vector was 95%, 1 vector was 10%, 1 vector 5%, 1vector was 0%. The through burn got worse as the project progressed.
Some history of the machine always helps. If this is a brand new machine I might go a different route to try and troubleshoot the issue… Different story if you been using it a few months or years.
It has the appearance of going out of focus as it moves toward the failing group of engravings.
The line width seems to increase in size, which again, I think points to focus.
These types of issues can have multiple causes, but there are a couple items that you could check.
The gantry and table are parallel.
It is correctly aligned.
If they are not parallel, then the focus distance is changing.
Sometimes an alignment issue or the tube resonance changing into something other than TEM00 mode can cause this type of operation…
Alignment can do some strange things… so insure it correct.
Generally the first thing to check it mechanical items that tend to come loose or move. Like mirror adjustment screws and anything along the optical path.
Most of the time electrical stuff works or it doesn’t…
The machine is maybe 6 months old, infrequent use.
I check the lens to table, 5 points it varies about .5mm on a 20mm distance.
We did notice what seems like an excessive amount of smoke buildup in the chamber. Might that cause be the cause, interfering with the laser beam, both reflected by the mirrors and direct path to the workpiece?
I suggest you confine personal information to only pm messages.
Bots collect this stuff… no telling where it will end up…
Maybe I’m misinterpreting you, but if the design is 100mm across the variance would be 5 * .5mm or 2.5mm off of focus…?
A good alignment from the back to the opposite corner it usually good enough… There is a 4th corner issue that can crop up, it’s common, but really isn’t as severe as yours is showing.
This is a good video on alignment… the adjustments are for a different type of machine with more adjustments, but the idea is perfect…
I guess I didn’t explain it well. Distance lens to table should be 20mm, I check it in 5 locations, 4 corners & center, the most variation was .5mm that is it measured 19.5mm.
I will pass on the video to our maintenance team.
I mentioned earlier excessive smoke, might that be an issue?
I kind of figured I misinterpreted what you were saying…
Anything in the optical path will degrade the energy transfer when the particulates absorb some of that energy…
I’ve run some pretty smoky stuff ending up with debris on the mirror side of the lens. The debris all over the machine seems to be more of a problem than smoke drifting around the beam.
I run my machine with the front door open about an inch for air flow. I start engravings from the front to the rear of the machine, so the debris field is not where I’ve already engraved.
I have replaced the honeycomb with a steel sheet, has alignment holes in it for templates and it is easy to clean off. When I cut I raise the material a small amount off the table and it vents from front to back.
The problem with any floating debris is that it ends up every where, much like spray paint in the wind… to good ventilation is one of the key ingredients to a good engrave/cut…
Off the soap box… I think it has to be something mechanical to do this… I can’t think of a thing, electronic wise, that could cause this …
When I review your first photo, it strikes me as a focus issue because the lines on the poor cuts are visibly wider… the one thing that I know of is out of focus…
Have you checked the TEM00 mode of the tube at m1?
This can also cause strange focus related issues… when my tube went south, I had to align it every time I used it and near the end, multiple times to get something done in one session… it’s resonance or TEM state changed very quickly… didn’t appear many other had this issue, but I know it effects the focus…
