Share your Parameter & Laser Speed Settings for LaserCAD

[wheelman]

Many of us use LaserCad with our DSP controllers and I doubt that many of them are properly optimized. Many of the settings in my machine are what they are because they are defaults. Obviously machines will have different values, but could we start a discussion of what hardware settings should be? Also, could we have a slightly more detailed and technical explaination of what each parameter is and how they are related? I'm referring to the two pages in the settings labeled "manufacturer parameters" and "user parameters". I'd like to bring some mathematical rigor to this to help some of us better optimize our machines. Please post your configurations and a description of the machine and if you have any modifications to it to increase/decrease mass of laser head, etc.

Here's screenshots of what I'm talking about:



I'm running 2 Lightobject 1800x1200mm 130w machines with 75mm focal lens.

Here's a list of the following parameters and what they mean, along with an example or a a method of determining it. I obviously don't know this, so I'll only fill in what I'm certain about and ask for clarification on the rest.
LASERCAD 7.78.10 MANUFACTURER PARAMETERS
Um/Pulse: [description needed] I believe this is a relationship between the actual distance your machine moves as a function of physical steps (or microsteps) of your axis stepper motor. This can be computed based on actual movement or determined by knowing your stepper motor step angle, diameter of pulley, gearing ratio, etc.
Pulse Edge - [description needed]
Key Direction - the direction that the keys on the control pad will cause the machine to move. Changing this from + to - causes the head to move opposite the way you push the directional buttons.
Limit Polarity - [description needed]
Range - Range (mm) of the axis. This value is a dimension that represents the maximum safe travel in a given direction on your machine, as measured from the position when the limit switch is engaged.
Start Speed - [description needed]
Max_Acc (mm/s/s)- absolute maximum acceleration parameter for a given axis. Setting the engrave or cut parameter in "User Parameters" will result in the machine occasionally crashing or erring when operating. If head is engraving on a single axis at 100mm/s and max acceleration is 100 mm/s/s, it will take one second for the machine to stop and change direction. This isn't a useful parameter in terms of how close to an edge one can engrave without crashing the machine. Based on some simple physics, the equation for constant deceleration to a stop is: distance = velocity^2/(2 x acceleration). Plugging in an engraving speed of 300 and a engrave_accel value of 3000 mm/s/s, the distance to stop is about 1.5 cm. Increase engraving speed to 500, and suddenly it takes 4.17 cm to stop. Place your engraving any closer to the edge than this, and you will likely crash.
Max_Speed - absolute maximum velocity in mm/s along an axis. Illustration above in Max_accel.

LASERCAD 7.78.10 USER PARAMETERS
Space Speed - [description needed]
Start_Speed - [description needed]
Speed_Factor - [description needed]
Space_Jerk
Cut_Jerk
Min_acc
Cut_acc
Space_acc
Engrave_acc
X/Y_Home_Speed
Z_Home_Speed
U_Home_Speed
Z_Work_Speed
U_Work_Speed
Key_Move_Speed (mm/s) - the speed the buttons on the directonal or software control cause the head to move
RunBox_Speed (mm/s) - the speed the laser head moves when "BOX" is selected from the keypad. The head will outline the maximum extents of the cut file
ClipBox_Speed (mm/s) - the speed the laser head moves when "CLIP BOX" is selected from the keypad. The head will outline the maximum extents of the cut file with the laser enabled, cutting a thin line around the extents of the cutfile.

Thanks for this - I'm in the process of trying to maximize my settings for efficient cutting and am trying to find a better way than trial and error. I'd be happy to update this if others contributed any details or descriptions. I'd also appreciate it if Marco could explain the jerk settings and perhaps share the base configurations for some of the machines he sells.

[Tech_Marco]

I read you and I totally agreed with you about the confuse of setting those parameters. I wish I know all but I don't because I am not the one to write program for the DSP. I have asked Mr. Li about those parameters but he never explained it well to me. He just gave me some number if a machine didn't work as expect, more like 'test and try'

I'm taking a trip to China from March 29th to May 4th and I'll spend a lot of time with him to discuss the future development of the software. I'll get as much as information about those parameter I can.

When I come back from the trip, I'm hoping that I can get you guys a new and more powerful software for the DSP controller!

For the 1800x1200 machine, you should select either "Normal" or "Slower" parameter on the USER Parameter setup.
The Speed_factor is important when doing cutting for small circle or round object. You may use 1.5 or 2.0.
Space_Jerk or Cut_Jerk play a key role when you found wobbling on cutting line. You may put down 10,000 to 15,000. In some machine like yours, I may set it to 8000

FYI, it used to be blocked on those parameters and not opened. I can honestly tell you that no one (DPS manufacturer) are able to tell you what exactly are those parameter means to be. It doesn't matter Leetro, Ruda, QC (our DSP). It is only opened to those laser manufacturers who will locked it after machine has been configured before leaving the factory to prevent a customer to change it. It is because any change to those number is significant. When I introduced the concept of DIY laser, I asked the programmer to open the parameter setup so that we can change parameters for different kits I'm selling.



Marco

[litterbox99]

I would agree !

I have been reading as many posts as I can to get ready. I'm building
a 900x600 using the X7 and by this weekend, I hope to have the XY
steppers moving up/down. I know I need UM values, but the laser
will be installed last, so that is not an option. Perhaps there are some
"base" values to start out with....

I would be happy just to get it moving and even simulate
some file cuts and etches.

This has to be a challenge to new builders so this project will help !

[SWMS]

Letterbox, I will see if I can find a link for you, I had to do this once. With regards to the PWM I am not sure.

Re the meaning of settings:

(I think)

The manufacturer parameters determine the overall maximums.


This is from the manual:

Space Speed]: During work, the max operation speed of laser head when laser off.
The value range of this parameter is limited to Axis [Max Speed] of manufacturer parameter, shall not be bigger than max speed of the manufacture parameter.
[Start Speed]: Start speed during processing, the value range of this parameter is limited to Axis [Start Speed] of manufacturer parameter, shall not be bigger than max speed of the manufacture parameter.
[Speed Factor]: Factor determining the turn speed in work. The bigger the factor is, the faster the work-speed is. Then bigger dither accordingly. Value range between 0~5, normally set at 2.
[Space Jerk]: Speed of acceleration during space process. The bigger the value is, the faster the space is; results in a bigger dither accordingly. Value range is between 10000~60000 normally.
[Cut Jerk]: Speed of acceleration during cutting process. The bigger the value is, the faster the cutting is; results in a bigger dither accordingly. Value range is between 5000~50000 normally.
[Min Acc.]: Min acceleration of axes movement during processing.
[Cut Acc.]: Max acceleration of laser head movement during processing when laser on.
Normally set below 1500.
[Space Acc.]: Max acceleration of laser head movement during processing when laser off.
Normally set below 2000.
[Engrave ACC.]: Max acceleration of laser head movement during processing when engraving. Normally set
above 8000. Too small a setting will lead to too long a distance before initial speed accelerates to engraving speed, causing a failed engraving because of out-of-range.


However, this is in Chinglish as we call it.


I've done some research and I think they mean the machinists term: chatter. This can mean hesitance wobble and vibration in the machine which will show up in your cutting.
When the manual says results in bigger dither they mean these words.

So, these are the ones I understand:

+++++++++++++++++++++++++++++++
Start Speed, the speed that the laser moves at from start - When you press start. If your manufacturer parameters are set to x axis 15 and y axis 15, if you this option to 20, the manufacturer parameters will over ride it and keep it at 15. mm/s

This ensures a smooth start rather than 0-500 mm/s in 2 seconds

+++++++++++++++++++++++++++++++

Space Speed mm/s : When the laser is off and moving into position into cut.
Space Jerk mm/s3 : When the laser begins to accelerate there is an inertia. Like when you put your foot down sharply on an accelerator or slam your foot on the brake till stop. Its a large number because its measured in mm/s3

+++++++++++++++++++++++++++++++

[Cut Jerk.] As above but when cutting.


+++++++++++++++++++++

[Min Acc.] mm/s2- minimum acceleration for the axis x, y ( not sure why you need this perhaps on corners?)


++++++++++++++++++++++
[Cut Acc.] Should be called [Max Cut Acc]: Max acceleration of laser head movement during processing when laser on.
Normally set below 1500 mm/s2

[Space Acc.] Should be called [Max Space Acc.] Max acceleration of laser head movement during processing when laser off.
Normally set below 2000. mm/s2

+++++++++++++++++++++++

[Engrave Acc.] Should be called [Max Engrave Acc.] mm/s2

Speed Factor - The turn speed in work I have no idea, I am guessing that if the head changes direction, e.g. goes around a corner, it does it at a factor of the speed set for the cut?

For some of these I am making an educated guess based on investigation.

Please contribute your thoughts. I have been trying to work these out from Chinglish for a long time!

Marco, any acceleration is in mm/s2 whereas speed is in mm/s and jerk is in mm/s3 It would be useful if the settings boxes were bigger so that there is room to put these units next to the boxes.

Thanks

[sshwarts]

Marco:
Since you mentioned about your upcoming trip and looking at the future of the software...

One area I'd love for you to explore with them is the PPI implementation (for cutting in particular). The way it's implemented right now the pulse width of the laser firing is a function of the speed. Most implementations I've seen, the pulse width is a constant or settable by the operator.

Scott

[SWMS]

Litterbox99

Here is the um/pulse calculator

You input this first then cut a 10 X 10 box and use the calculator to make the adjustments.


http://www.buildlog.net/cnc_laser/belt_calcs.htm

[seeigecannon]

Letterbox, I will see if I can find a link for you, I had to do this once. With regards to the PWM I am not sure.
...

Thanks

Thanks for this. I have been working on a better English translation for this program that can be found here:
https://docs.google.com/document/d/18_a ... sp=sharing

I have the document set up so anybody can edit it, so feel free to play around. I will be adding your recommended changes tonight.

Edit: I got those changes in. I also managed to fit in units.

Screenshot 2016-03-29 19.21.28.png (34.87 KiB) Viewed 4640 times

[SWMS]

Hi, I think thats all ok. However, some of your other units aren't in mm/s or mm/s2.

Generally I think thats the only section on the software that doesn't make much sense. I still find speed factor to be a mystery as to how it works