Optimum focal point

Community Laser Talk
1

I know this has been discussed a lot also. As I get older I wish to know more than my brain will allow.

My ramp test shows the center of the fine line on the ramp to be 16.1mm. I have changed that position many times while cutting 3mm to 3.5mm plywood - mdf core. I have decided with what I am diving into at this time to place paper masking to both sides of the material. The extra expense of the masking translates to less cost than the time it may take to clean up slight blemishes from smoke etc. for me anyway.
I have most often set the focal point to the middle of whatever the substrate is in thickness. If the nozzle gets too close to the substrate I have more smoke which is taken out with my two exhaust fans. There is quite often more residue on the top surface and even on the bottom when masked. Masking on top and bottom creates some resistance to cutting all the way through with speed at 10mm/sec and 60 percent power with a mA reading of 16mA - 17mA. I can lower the head so that I read about 15mm from nozzle to substrate with better cut through. Haven’t experimented with it much lower. What confuses me most is the supposed setting of the nozzle at 10.6mm. That gives me a real mess on the surface. I use about 40psi air assist when cutting.
I am probably rambling, sorry. I am trying to make sure I get max time out of the tube although when it does go I will get into the piggy bank and get one from Cloudray.
BTW: I turned the tube so the inlet-outlet is on top, no problem at this time.

2

Didn’t think it would be an issue. The holders for these tubes do a good job and are repeatable position wise.

Where did the 10.6 mm height come from?

I’d think if anything, you’d set the focus to be (focus + 1.5mm) for a 3mm mdf… I don’t make these adjustments, but if you were going to it’s usually a target at the center of what you are cutting.

I stick a long nozzle on my 2" and it’s about right for a 5mm magnet to slip in from the nozzle tip to the material… I run 60lbs when I cut… I also have a steel plate, no honeycomb and the lid is open about an inch for air flow…

:smile_cat:

3

With my original standard lens (f50.8mm) I process mdf and hdf with 30mm/s and 45% power (12mA), distance from nozzle to material is 17.5mm, reasonably problem-free. I use relatively little compressed air, I don’t really need it at only 3mm thickness. There is a thin film at the edges of evaporated glue and wood, I wipe it off easily with acetone. My observations are that the more extraction I can get in the cabin, the less the surface gets stuck with the vaporized smoke. I have to open the cover 2cm to get enough air for the exhaust fan.
At up to 4mm I focus on the top of the material.