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View Full Version : Laser head overshoot on engraving area ??



paul simonson
07-22-2017, 6:09 PM
Suddenly today I am having a new issue with my chinese laser, a 50W Blue and White.

In a nutshell, the laser head is using a much larger amount of room after each side to decelerate and accelerate on its way back.

In the image below I have combined two images to show clearly whats going on. You can see the laser head is about 5 cm away at each sides and the burnt image is only about 4 cm's. Prior to today I would barely see the extra room needed to achieve this, it was more like a few mm's than cm's!

http://i.imgur.com/LIC5MvH.png

At the same time, the specified speed for the engraving is never achieved, it just doesn't get close to what it should be doing in my eyes. I'm telling it to do 300mms and it looks like maybe half that?
Absolutely huge overshoot. I must have changed something somewhere but I can't imagine what. I also had some issues with rdworks on my machine so had to reinstall that today. Sigh. Have rewritten `vendor settings` on the machine through rdworks but I'm unsure truly if this is a software or hardware issue.

Anyone know what affects the `run up/slow down` distance & speed?

Bill George
07-22-2017, 6:45 PM
Contact the people you purchased from, they will have the correct settings. Blue and white 50 watt ebay machine tells us nothing brand, model, power and controller would help but in this case you need the set up info. But what your showing I would consider normal or good enough.

Kev Williams
07-22-2017, 7:34 PM
That amount of overshoot is completely normal for 300mm/sec speed...Overshoot is dependent on the speed you're telling the machine to engrave- what you're seeing is the overshoot you'll get no matter the length of the engraving at 300mm/sec... It's 'built in' to allow for accel and decel time for the head to speed up/slow down, but the controller doesn't care about the actual distance of the engraving. For that short a distance to engrave, turn the speed down to 120 or so and you'll see MUCH less overshoot and much faster engraving :)

paul simonson
07-24-2017, 6:59 AM
I've engraved at 300mm+ many times and never had an overshoot of more than a few mm. An overshoot of any real size would drastically reduce the amount of cutting area you have on your bed. Mine is 500x300 and the overshoot i currently have halves the cutting area. Something has changed, wish i knew what.

Michael Henriksen
07-24-2017, 7:16 AM
These are my settings. How do they compare to yours?364407

Kev Williams
07-24-2017, 12:37 PM
Mike, those settings are circle speed limits and backlash compensation settings, which won't affect the overrun Paul's having... find your machine's speed and acceleration settings and take a pic of those, as those CAN affect the overrun.

They'll look like these:
364420
note that these are my machine's factory default settings, not my actual settings, and my machine uses PHCad/Lasersoft software..

Dave Sheldrake
07-24-2017, 9:40 PM
It's an SH 350D the ebay "Blue and white"

Few Chinese machines of the smaller type will make 300 genuine MM's per second before stuff gets funky unless you go to the all-in-one CCM servos (that get very close to the speed of a trotec)

https://www.youtube.com/watch?v=rlO0k23WFUc