Anyone "overdrive" their Chinese laser?

[Kev Williams]

My 1390 Triumph came with PHCad and PHSoft laser software, which from what I've seen from screenshots is just re-badged "Laserworks". FWIW the PHsoft is a newer version that never works right...but that's another story.

Anyway- the machine and software came loaded up with a max Y-axis speed of 300mm/second and X-axis max of 500mm/second. I found out that I can speed things up by changing the machine parameters in the software. So far all I've done is moved the X-axis speed to a max of 700mm/second. I've tweaked the backlash at that speed and I get nice rastering results. The only negative I've noticed is the increase in the left and right edge overrun. At 700mm/sec it's more than an inch- no problem as long as I keep what I'm engraving farther than the overrun distance (or I get "not enough space" on the machine readout)

I'm curious as to the ACTUAL max speed this machine will go. Haven't had much time to experiment further.

I'm also curious if others have sped up their machines, and how much?

[Ross Moshinsky]

There was fairly in depth discussion about this 2 or so years ago when a lot of people were buying Shenui lasers. I believe most of it got filtered into this thread: http://www.sawmillcreek.org/showthread.php?181819-Chinese-laser-purchase-Shenui-Laserworks-tips-and-tricks-thread

If I recall correctly, anything over 600mm/s didn't work well for one reason or another.

[Dan Hintz]

You need to be careful about missed steps at high speeds (acceleration, actually, but high speed tends towards high decel rates, depending upon how the software handles it), Kev. There's no position feedback with those systems, so missed steps can be invisible on small projects but quickly add up over a large one.

[Kev Williams]

My Triumph has position feedback, assuming you mean it and/or the engraving software knows the coordinates of the laser head. My ULS and NH machines have the coordinates on the machine, the Triumph coordinates are on the computer. My NH machine has an issue (I wish they'd find an answer to) when running the cylinder attachment- sometimes the X-axis will jump, sometimes several steps. Sometimes while engraving, but usually when moving slow towards another spot to engave, or towards home. But the machine or its controller doesn't know when it's skipped. I know it because I can hear when it happens, and I also have home position marked. When it's skipped the head is noticeably out of position...

Anyway, I haven't had any skip issues running at 700. Yet. ;) The decel-accel at the turnarounds seem very smooth. I'm sure the excess overrun helps with that. I'll have to experiment with higher speeds and check repeatability.

I'll check that link Ross, thanks! :)

[Dan Hintz]

Ah, my bad... in my mind I was thinking Chinese system with DC tube. Those don't have position feedback, so losing steps is a major issue... not so much if the machine knows and can compensate.

[Scott Shepherd]

You realize what the good news is here, right Kev? It means with it running faster you get to set your Cermark settings all over again :)

[matthew knott]

Think your right Dan, there is no feedback as such, it will be an open loop system, Kev your machine doesnt 'know' its position, it just thinks it does, if you disconnect a motor or belt the software will report a position but it wont actually be there. Our Epliog has encoder feed back and as everyone knows that has one its pretty hopeless at keeping position as it gets dirty and messes your parts up, I've had a lot less trouble with el'cheapo stepper motors than the 'encoder strip' but then our extraction was not really upto scratch.
Be careful Kev looking for the extreme performance point of your laser, you might get close to being on the ragged edge but a slightly tight belt in one spot, or a dirty bearing and it will miss steps or just stop in mid flow and ruin your part, 600mm Sec is the maximum we go and so fair zero problems.
Matt

[Dave Sheldrake]

There are over-run settings that can be adjusted as well, not sure about Shens but the HX's and Weike's can do 1,000mm ps for rastering. Much anything above 75mm ps for vectoring usually ends up with wobble corners.

On most Chinese made DC units the head is sent XX distance and the software assumes that is where it ends up.Best way to find out is pause the machine halfway through a job, power it off, move the head an inch or so by hand then restart and see if it compensates.

cheers

Dave

[matthew knott]

Dave , i don't think any (small commercial) use absolute encoders, they are always incremental hence why they have to home at power on as they dont have clue where they are. Am i wrong ?

[Kev Williams]

All of my machines-- laser and rotary engravers-- "know" their positions only because of the last-known stepper motor's positions the controller told them to go to from the 0/0 home position. If any steppers, or the laser or spindle heads get moved in any way other than the machine's controller, then the displayed coordinates won't be correct, and the machine needs to be zeroed out via 'reset'. In that light, my Chinese Triumph, American ULS and French NH machines are identical, which is fine by me.

So to find out if the machine- ANY machine- is skipping, it's a simple matter of running a text test in 'overdrive' for several lines, re-zero the machine, then run just the very first and very last word in the test at a slow speed to see if the engraving aligns.

[Dave Sheldrake]

Pretty sure you are right Matt, as yet I haven't seen a budget machine with absolute encoding (the eplilog as you say isn't exactly accurate with their idea of encoding strips) but there may be a model somewhere I don't know about. The only cutter I have that does is the Mitsu with the usual backlash encoders and positional encoders but that doesn't really qualify as a "budget" box ;)

Dropped steps when using G91 is going to cause problems if my old cnc's were anything to go by :)

Kev, much above 600 mm/ps is going to end badly on either a job going tilt or something in the machine going bang.

cheers

Dave

[Rodne Gold]

Even if your machine can be "overclocked" , it doesnt mean it's actually faster in terms of thruput
Try this , set the speed at max and engrave a word or 2 of text , time it , then set the speed to 100mm/sec and time that..
In our case , the MUCH lower speed was a lot faster as the machine did not have to "overshoot" anywhere near the distance it did at high speed

[Dan Hintz]

Also, what works now in a cool environment and low workload may very well begin losing steps as the workload increases and the coils heat up. Once any real work is asked of the stepper coils, they'll warm up and the physical parameters change. I'd always been tempted to try and find the resonant frequency of my ULS's steppers, see if I could get it to falter under heavy load, but time being what it is didn't allow it.

[Rich Harman]

I've tried rastering at 1,000 mm/s, sometimes successful other times it loses steps. At 800mm/s it hasn't lost a step, but there ends up being some after fires at that speed so it is not that useful. I don't raster much and when I do it is always less than 400mm/s.

I have turned up the travel speed to a conservative 700mm/s. The only time a step has ever been lost is when run at 1,000mm/s.

Your mm/s may vary.

[Kev Williams]

As noted, I've had no issue at all at 700mm/s, and I've done a lot of work at that speed. As for vectoring, the thing will cut 4-6x faster than my LS900, but I have noticed choppy radius's on name badges I cut. I'm pretty sure there's a way to slow down radius cutting while maintaining straight-line cut speed, I just haven't figured it out yet. ;)

My main interest in gaining raster speed is with engraving the large anodized aluminum operator panels I build, which will be using most of the 51" X-axis space. However, while saving time is nice, the fact that this machine will engrave 2 of my larger panels in one shot vs 1/2 of one panel in the LS900, allows me time to work on other things, and not get interrupted on THOSE jobs for a second setup. Engraving time may be more, but MY time will be less, regardless of how fast the machine engraves. I don't have a bunch of employees running machines, my BIL runs the Concept, and the ULS (unless I'm using it), I run everything else. Most days I have at least 3 machines running jobs all day, and a job can be done for several minutes before I get back to it. So faster isn't critical, but - it would be nice!

I will be experimenting with higher speeds, and report how it goes!