wiggly rectangles on a chinese machine.

[tommy suriady]

Hi guys,
Havent been here for the longest time due to work. Just moved to another island in Indonesia to set up a laser cutting workshop using coherent highliht 1000fl fiber laser! But interestingly, I got a lemon.:eek:

Fortunately, Coherent speedily sent a replacement unit by air. All the way to Indonesia! Footing all costs incured including the customs which amounts to about 15k usd. Good job to the Coherent guys.

Anywae, back to CO2, My 60x90 80watt is acting up! When we cut a simple shape with rounded corners, eg. 2in x 2in, with .2in rad rounded corners, the cutting line becomes all wiggly. Like it was shivering as it is cutting. And cutting 10 of the same shapes will get you different wiggle patterns. I attach a picture.

Anywae, has anyone of you experiencesuch thing? I checked everything and they seem firmly attached. Seems like the cutting is kinda soft( no sharp corner on survace vs side).

How do I know if it is the laser, or is it the stepper motor? Notice that the thin straight line across is perfectly straight. Please help!

Thanks, before hand.

[Dan Hintz]

Check your carriage for rigidity. Make sure your belts aren't loose. Check your pulleys to make sure they are attached to the axles properly. Make sure all optics are solidly attached.

[tommy suriady]

Hi Dan,
Checked all those. Machine is rigid, belts are good. Mirrors set. Nothing loose and no strange noises during cutting; fast or slow. I am suspecting the laser. If it is near lifetime, could the laser output starts to wiggle? Any mechanical problem would make shuddering sound, right? And the jittery line has pretty high frequency it seems. I am cutting at 1m/min at 80% power. The thin line cut at 5m/sec at 1%power. But cutting the outside perimeter at 1% also results in wiggly line.

Tommy Suriady

[Scott Shepherd]

If it is near lifetime, could the laser output starts to wiggle? Any mechanical problem would make shuddering sound, right?

I don't see how a failing tube could cause lines not to be straight, but I could be wrong. You wouldn't hear any shuttering, the distance it's moving is so small, it wouldn't be obvious.

Looks to me like a loose lens or mirror, or something in that chain is loose. Might not be a belt or pulley, but something.

[Jerome Stanek]

check and see if you have a lose mirror or the lens is loose vibrating when moving

[Robert Schmiede]

Hi tommy, I have a friend here in Australia who had the same problem. It was a loose wire on the stepper motor. Turn of the machine,follow the wires from the stepper motor down to there controller and check the connection. Hope that helps.

[Kev Williams]

If all else seems tight and rigid-- If you're okay with disconnecting the belts and re-connecting and tensioning them, do so and check the belt cog wheels for free movement. If the cog bearings are the least bit 'chunky', that can show up as wiggles. Doesn't matter how old the bearings might be, I just found the left-side X-axis cog bearing on my 10-month old Triumph isn't rolling smoothly, got a new one coming...

[Kevin Gregerson]

What seems rigit sometimes isn't. try moving the laser carriage, see if you feel any inconsistencies in there as you move it. The movement should be perfectly smooth with a consistent resistance. Check the spring being your optics carrier as this sometimes goes bad. I've also seen bearings go bad with the runout causing the head move back and forth at a random pattern.

[tommy suriady]

Hi guys,
We solved it! Turns out it is the lens that was loose. We did maintenance on the machine and cleaned the lens. Guess we forgot to retighten the screw holding the lens. We kinda got a lightbulb over the head when one of us asked if one of the screw behind the lens tube needs to be tightened... thanks, everybody.