Hi !
I have a question about cutting with the laser. I’ve done test cuts with the material running a few different speed/power options. When generating a material test I get a good clean burn through.
I generally am shooting for the middle of the speed/power curve that gives a clean cut with optimal time. I’m cutting 1/2" red oak and I’m cutting with the grain.
The pattern is pretty detailed and the issue I’m having is that a while A small 5 mm square will cut and drop out perfectly, and a linear test of the cut on a straight line burns cleanly through, but when I’m running the project, on some long linear cuts they are not completely cutting through.
Is this common ?
I’m using a lasertree K30 diode which produces about 30 watts, the speed is 120 power at 90. I can get a clean linear test cut at 150 speed and 75 power on a 150 mm test line but when cutting the project at 100 speed and 90 power I’m getting some cuts that don’t break through and won’t punch out, they generally occur near the 3/4 to end point of completion. The cut time on the project is a little over 2 hours and I’m not getting any debris on the lens.
I need 4 panels to complete the project so I’d like to cut the time down not increase it.
Is this common that a long time on a project cut will differ from material tests and other cut/burn tests ?
“the speed is 120”
We have to guess if after the digits, there is a unit? mm/s? mm/min? inch/min or some other combination? (Idem for power, although it is more generally a percentage.)
That said, I mostly cut thin plywood (having only 10 W), and indeed, I find great differences in cutting depth over a whole board. Sometime, I have to finish the cut with a blade, which can be time consuming (but I am a hobbyist). I find myself pushing the specs (slowing a bit, upping a bit the power) to avoid this as much as I can.
It might be because the plank is slightly warped, resulting in focus changes.
But also, and more importantly, because wood is a live material, not uniform, so some areas might be harder to cut than others. This is even more true for plywood, with layers of glue, which are irregular as well.
AFAIK, “cutting with the grain” isn’t important for a laser. It is with manual tools, perhaps with CNC, but laser just burns.
Note 1: air assist helps greatly with cutting, if you are not using it already.
Note 2: nice title… 
Not descriptive at all in a laser cutting forum, but nice.
… With my 60 watt laser I can clearly see a difference if I cut with or across the wood fibers, especially with solid wood, but also by cutting at plywoods last wooden layer.
In the case of diodes, you have a problem with diodes oblonged beam. It is in some cases 50% longer as it is wide. Imagine an ax who has doped so wide cutting surface and chopping across the fibers …
Thanks Bernd, we learn new things everyday.
As I practiced only plywood so far, with basswood or other woods with very little grain, I suppose I didn’t see that. And perhaps I experienced that without knowing it was related to grain.
Now, most designs will go with and against the grain, when they are convoluted, and I doubt you can adjust the power along an axis (ie. x axis getting 10 % more power than y axis, for example). Might be a feature request for LB, though…
Thanks guys, speed was in mm/m, I am using air assist and a honeycomb underneath for better air flow.
There is a hint of a warp in the board but I didn’t consider it excessive. I’m going to elevate it off the honeycomb and see if that helps, it usually helps keep the residue from the oak off of the final product.
I was just curious if others had similar issues when cutting a large project.
And, yes, sorry the thread name could have been a little more descriptive for future searchers but after wasting a nice piece of red oak and few hours of time I felt the need for a little humor !
Are you using red oak or white oak?
Oak in general is very hard and fibrous, white oak is downright hard.
Think you have decided to use one of the most difficult woods to cut with a laser. My opinion of course. lol
A 1mm difference is tiny, until you have it in your laser focus.