Replacing laser controller

[Mike Lysov]

Hi guys,

can somebody tell me how easy to replace a module that controls tubes and motors?
What is the main block called that accepts G-CODE from a PC and tells the motion controller where to go and what speed to use to cut/engrave? I guess the same module controls a tube power.

I am still trying to understand why my new laser cannot do small designs at the speed it told to do them and instead after some point it drops the actual speed of operation if I try to increase job speed My other laser(LaserPro Spirit) does not have this problem. When I increase job speed the actual speed of head movement is also increased.

I guess it has something to do with software installed on the new laser that processes commands because g-code seems to be correct.
I asked MFG why it happens and I was told that I need better(and more expensive) motors because the ones I have now cannot accelerate and change direction of movement at high speed. I do know know if it's true but the motors I have do not look cheap and small. They are much bigger than the ones I have on the LaserPro Spirit laser. And even if they are right how changing the motors only can change the actual speed of movements?

If you are using chinese lasers with LaserCut software and DSP system can your laser move fast on a small 5-10cm square without rounding corners? If you increase a job speed does your laser head move faster.

Mine that also has DSP based motion controller but a different control panel cannot do it small shapes with straight angles, it makes fillets on corners instead. If I set dwell time to some amount it will make straight angles stopping at them. That would be ok with me but when I use dwell settings my laser moves much slower even on straight lines and slows down and stops on each segment.

That leaves me without any option to do small things from thin material faster. So for now with current situation my 280W laser cannot cut out small shape of 3mm thick MDF faster than my 100W LaserPro.

Is that how all CNC controlled lasers work? If they are then what principle is used in LaserPro lasers

[Rodne Gold]

A whole lot of factors are in play , inertia of the actual head and moving parts , bearing tolerance , belt backlash and motion system slop , the controller , the type of feedback the motor has . the type of drive system , DC servo or stepper. Kinda like driving a 5.7 L 300hp stock 67 Camaro (in your case , probably a 308 72 Holden Monaro or a HQ ute) round an autocross course vs a 2 litre 120hp late model hot hatch , the hot hatch will do it quicker....

[Dave Sheldrake]

I do know know if it's true

It is, a 280 watt machine by nature of the available power really needs to be driven by Servo's and not steppers. Servos feed back information about the position of the laser head, steppers don't.

The available acceleration / deceleration of a good servo is far superior to the step drives most far eastern machines use as well as a servo providing feedback to the control about it's current position at any given time.


system can your laser move fast on a small 5-10cm square without rounding corners?

depends on the machine, most of the bigger Chinese machines are flatbed types with the laser tube fitted inside the gantry, anything over 55 to 65 mm per second and the corners give way, it's similar as Rod said, try driving your Ferrari round a 90 degree bend at 150 mph and the back end lets go. It's the same effective forces at work causing it.

It's harder (requires more "force") to move a heavy laser gantry but the flipside is, it's also harder to slow it down as well.

cheers

Dave

[Mike Lysov]

You are right guys, it has 400W servo motors installed, not steppers. It may be not just a problem with the motors, it is kind of bad software that controls and dictates the laser how to do things. It can out of no reason start doing a circle where there is no circle in the job it should be doing. Just yesterday when I was trying to cut out the "&" symbol the laser cut out the top internal part in it and when it finished it it started doing a big circle from the point where that part ends. I looked at that part closely and it was closed curve and the only way I could finish this part the way it should be done was to change prefetch tolerance to 5 times bigger value than I usually do. I was lucky it did not change the shape look with such a big tolerance value.
These things do not happen all days and sometimes I can understand why it happens(two curves are crossing each other) but it has not been the case with that "&". That's one of the reason I want to change its controller. The other reason that software that sends all jobs to the laser has almost no functionality. It cannot even draw a true circle, it has a circle tool but if you draw it and tell the laser to do it without using prefetch it will do it very slow, like it consists of many small segments instead of 1-4 arcs.

It comes with a printer driver and I can bypass their software and print directly from CorelDraw and probably any CAD software but it should work good only from software where jobs are done in true DXF. However I cannot find any CAD software that allows me to do artworks based on fonts and with CorelDraw it just awful considering how it works with curves.

[Rodne Gold]

You can change the controller to something like a RDLC320 and run better software (laserworks/rdcam).. in all probability it would work as all the motherboards are immensely configurable , you would need the Mobo (rdlc320) and the matching LCD display - under $400 , you would have to mess with the wiring and perhaps mounting configuration..it's not that easy as a drop in , but not that difficult either.