LS3020 - Engraves but will not cut

[ADavies]

Hi,
new user with a few questions regarding the LS3020.

I've attempted several times to cut various different materials (5mm wood, 4mm card), first as per the cheat sheet then when this fails, experimenting with different settings. It probably cuts a little less than a millimetre. I've tried multiple passes which don't really seem to progress any further than the first cut. The lines are all crisp and consistent in regards to width but no depth.

I experimented with increasing the current potentiometer which really only served to generate a flame, scorching the material and making the cut appear less clean. Is there a suggested optimal current or are people generally adjusting it to taste.

Is there something in the newly draw dialogue box I'm missing that toggles between engrave/cut?

What's the purpose of the honeycomb bed?

Cheers

[PhillyDee]

With newlydraw, you need to select what you want it to do with the mouse tool (pointer with a dashed box).

Select the shape, and select either SCAN or CUT. Scan engraves like a dot matrix printer prints, and cut follows the line.

With my LS3020, it currently cuts at 10mm/s, engraves at 400mm/s and all this is on 60% power (6 full turns of the potentiometer knob).

It used to cut at lower, but I have around 200 hours on the tube now.

http://www.laserscript.co.uk/phpBB3/vie ... ?f=9&t=192
Is where to put the speeds and feeds.

[ADavies]

It was in cut mode each attempt I made earlier. It's probably also worth noting that even extreme changes to the cut speed/power yielded seemingly similar results. If there was any difference it was negligible.

Do I have alignment issues? As I say, the cut is sharp and focussed there's just no depth and DEFINITELY no danger of it cutting through anything but paper as it's currently functioning.

[ADavies]

Any other suggestions/advice? While the engraving is cool the primary reason for the machines purchase was to cut things.

Cheers

[PhillyDee]

Best to go back to basics and confirm correct alignment. Also check the spot pattern at the air cone. You will need some 3mm ply or similar, build the wood as close to the nozzle as you can get and fire the laser. The mark left should be perfectly round amd central. Also, how are you focussing the laser? Back to basics is the best way. Can you say what settings you have tried? Materials etc? Turns on the pit, and mA.

[ADavies]

What's the spot patern? The mark the laser leaves if you test the laser? It's about 0.5mm and perfectly round. You say it should be perfectly round and central. Central to what?

I'll have to get hold of some 3mm ply to try what you're talking about but will give it a go.

As I said, the cuts are very clean. I'd assumed poor alignment would scatter the beam and result in a mis-shapen spot? That's not really the case, just not getting any depth.

I'm focussing the laser the supplied ruler distance from the bottom of the head that outputs the laser. Is this correct? Again, it produces a tight clean cut.

The materials intially used were dense 4mm card and 5mm ply. I've since tried acrylic which yields similar results.

The pot is probably at little over 1 and a half rotations and meters 10 mA at peak. Any more than this seems to produce a flame and scorch the material... and doesn't appear to cut any deeper when it does so. Just messier.

[PhillyDee]

Sounds like the exit is fine, I think power is just too low. If it is flaming, you must not be using air assist, or it is not working. There should be a flow of air out of the end to keep debris away from the hole and lens. I only get flaming when forgetting to use air assist.

Try 5.5 turns of the pot, air assist on, and around 10-15 mm/ s on the cut.

[Matrix]

I'm focussing the laser the supplied ruler distance from the bottom of the head that outputs the laser. Is this correct?

We use a slightly different machine, but on ours the focus distance is measured from the position of the actual lens, which is some way inside the "nozzle".
From your description of a 0.5mm spot, it sounds like the focus is the problem, as a laser spot of 0.1mm or less should be easily achieved.
Naturally, I don't know exactly where you should measure from on your machine, but a series of tests at different heights will soon hone in on the perfect value - just look for the setting that gives you the smallest spot.
If you have (or can get) some, I'd suggest using a scrap of clear acrylic for these tests - the spot will hold its shape better than on card/paper, making the sweet spot easier to find. It will also help to show any alignment problems - the hole made by the laser should be perfectly circular, and perpendicular to the surface of the plastic; a slanted hole is a good indication of small alignment problems.

Hope that helps, best of luck.
Steve.

[ADavies]

Right, initially I was measuring the distance from where the laser is mounted to the arm. So if I take the bed higher and measure from the lens centre hopefully that'll help.

Cheers for all the suggestions. I'll report back with my findings shortly

[ADavies]

Is there a lens inside the nozzle that you're speaking of as opposed to the angled mirror reflecting the beam downwards that I thought you meant and just measured from?

The results of this were much much worse resulting in a 3mm undefined scorch on wood rather than a neat cut. The cutting laser is also a good cm to the left of the red dot now whereas my initial method meant the 2 were perfectly aligned.

Re-setting to my original focus but increasing the voltage I just managed to cut a circle out of the acrylic ruler supplied with the laser... attempting the same on ply didn't make it through the wood but succeeded in scorcing a good 5mm either side of the cut :/