Chinese Laser: Vector / Raster Misalignment

Long time reader, first time poster. I've got a problem. My laser will not raster and vector in the same location. I have a redsail m-900 with 90 watt reci tube. I ditched the steppers and put in clear path servos. Basically my raster is about 5 mm to the left of the vectored graphic. For instance, if I draw a square, set the laser to cut and engrave the square, the vectored square and rasterd square do not line up. I've scoured the internet looking for answers. I can compensate for this with backlash, but I'm only unidirectional restoring. Maybe I missed something, but I've done a lot of testing with machine parameters, acceleration values etc with no luck.

Any suggestions are greatly appreciated. I can post pictures if needed, but its pretty boring to look at. Thanks!

Did you switch out your motion control?

Same question you went from Steppers to Servo motors and had to change out the driver boards and now figure out how to run the Servo motors off the OEM control card that was set up for steppers? Now your in a situation that going to take a lot of trial and error or a real CNC expert. Good luck.
Other question, did it work before you took out all the stepper motors and old control system? If so I would put things back the way the same way it came from the factory.

Same motion control board. Top wisdom tl-403cb.

I swapped the motors because the resonance of the steppers was terrible. I did not do exhaustive testing before swapping. The results were unacceptable before and are much better now that I'm running servos. The servos work off step and direction. They are manufactured by teknic and are marked as drop in stepper replacements and run step/dir. (stepper killers). I'm a big fan of their product line. After wasting money on some foreign servos that didn't work for my needs at all -- these things kick butt. I experienced the offset with steppers layer to layer, but I attributed it too a file output problem. For instance if I was to raster an image and then cut a circle around it, it would be off center. At the time I figured it had to be a problem going from corel to autolaser. I had seen where other people were suggesting to draw boxes around the graphics and group them as to avoid the misalignment error. It was not until I attempted to vector cut and raster the same layer that I realized it was not a file layer based issue.

I've been offsetting the graphics in the autolaser. But yesterday I ran about 50 test trying to fix the offset issue within machine parameters. My offset remained very consistent which makes believe I'm over looking something simple. If thats the worst I have to deal with Its not that big of deal, I was just really determined to track this down and could not. I'm far from an nc expert but this isn't my first computer controlled machine. Thanks for the input!

David,

Is there a zero setting in the raster and vector mode. By zero setting, it's where the laser usually begins, probably upper left hand corner. Maybe they aren't set the same? Also, the steps the motor takes... are they the same for X and Y for both the actual motors themselves and the software setup? I use CorelLaser and have those settings in raster (etch) and vector (cut) modes. Easy to miss as the labeling isn't very clear if the software is of the Chinese variety.

Mark,

I'll look into that. On my machine origin is upper right. To my knowledge can not separate the zero point based on raster vs vector. But that gives me something to dig through the manual and hunt for again. The steps the motor takes should be the same as the motors are the same for x and y. The step resolution has been configured via the autolaser software and is constant to both raster and vector. Only raster is offset to side by the ~5mm to the left, always. I went through and tried to exhaust all of the settings that I didn't fully understand what they did yesterday. I went through all of the various path optimization settings, things such as laser repair. With that particular one I could change the rasters off set to the right, but it would jump by that same interval. So something is deff wrong in the software. It errors by the same amount at a given speed extremely consistently. In simplest terms, the laser fires too soon when restoring resulting in a position error. Thanks for all the input guys. With any luck, I'll get it sorted out soon.

I have owned both Servo machines and Stepper machines, retro fitted milling machines and the like. Servos are faster but also have issues with encoders, just as steppers have with losing steps. But either system designed and engineered for a certain application is usually pretty trouble free.

I just checked out the Clear Path website and it looks like the Stepper Killer motor concept is pretty sound and works for a lot of applications. I think maybe your old controller might be a problem?

What happens if you try bisectional raster? Do both raster directions lineup with each other or is there more offset?

I just was wondering if its a timing issue? The old controller or driver modules not being really intended for faster operation with a Servo. Vector is just on and off and not rapid cycle like a raster job.

I will do some testing and post pictures soon. It seems to me that the laser is firing uniformly too soon. I don't think this has anything to do with steppers v servos, as I was experiencing the same thing. I've been swamped this week and hopefully will have time to run more test this weekend.

Are you sure it's not a software problem ? Place all your graphics inside a bounding box, both vector and raster and center them within the box.
or center some text inside a bounding box and have one color raster and the other cut. See what happens

Ok so I was totally wrong. This issue has been resolved, thanks to the fine folks over at Tecnic. There is a regressive auto spline function on the clearpath servos. This computation takes a small amount of time to complete, thus the offest in position. My understanding is that you can not completely disable this function, but as you decrease it the alignment issues lessen. My tech wiz has come up with a micro controller that will delay the signals going to the laser. Just waiting on the parts to arrive. Thanks to everyone here for the suggestions. I must however note the level of customer service Tecnic went to. I posted this about a week ago. Last Friday, I received an email from one of the Tecnic engineers with instructions on how to solve my problem. I didn't reach out to them. They emailed me, referenced this post, and offered the solution. Yup. They most have google alerts set up or something. I have never experienced customer service of this level..ever..on anything. After the nightmare I went through with leadshine, this was very refreshing. Further proof that you do pay or what you get. For anyone considering servos for any future products, I can not recommend the Clear Path servos by Tecnic any higher. These guys are a true class act all around. Amazing product, even better customer service. Cheers

It's always pleasing to read about good references. Thanks for sharing

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Originally Posted by David J Fisherr

There is a regressive auto spline function on the clearpath servos. This computation takes a small amount of time to complete, thus the offest in position. My understanding is that you can not completely disable this function, but as you decrease it the alignment issues lessen. My tech wiz has come up with a micro controller that will delay the signals going to the laser. Just waiting on the parts to arrive. Thanks to everyone here for the suggestions. I must however note the level of customer service Tecnic went to. I posted this about a week ago. Last Friday, I received an email from one of the Tecnic engineers with instructions on how to solve my problem.

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David, I'm using the same motors and having the same issues. Love the motors, but need the same fix. Any chance you could help me out? My father does prototype PCB mfg, so I'm sure we can build the micro controller, just need to know what you did. Any help would be FANTASTIC!

I know we can "tune this out" with settings in our software, but it will be a pain as we run 4 lasers and would have to change the settings to match each machine everytime we download a file.

Thanks!