Benbox Laser DIY Machines
Software => Grbl Controller => Topic started by: Administrator on February 02, 2016, 04:19:16 PM
This link explains what Grbl is for those of you who may not know:
This link has the Latest Grbl down load link. It's on the right side of the web page and it's called "Download ZIP":
This link tells you how to use your Ardunio IDE to compile and flash your new Grbl software:
After you get your new Grbl software into your laser machine, this link covers configuration:
When you flash (install) a new Grbl version, some of your settings previously save in the controller board may get wiped out! So as you configure or re-configure, write down the settings you change so you'll know what they are!
These are the settings I changed:
These are changed to re-calibrate your stepper motors. For my Benbox DIY I ended up with values around 80.0000. There are formulas all over the internet to show you how to calibrate your X axis stepper motor and your two Y axis stepper motors. Once you determine what your corrected values are, write them down!
$100=314.961 (x, step/mm)
$101=314.961 (y, step/mm)
I also changed these values. In my previous Grbl version the default values were 10.000 and I changed mine to 50.000 because it helped the steppers maintain a more constant motion up until the end of the line. With the default values of 10.000 the motors would accelerate slowly while getting up to speed and then towards the end of the line, start to slow down...not good when using a laser! 50.000 gets them up to speed faster and holds that speed until the last second.
$120=50.000 (x accel, mm/sec^2)
$121=50.000 (y accel, mm/sec^2)
Nice list of Grbl Tools:
Great info help Ralph. I have downloaded that lot.
Just need to read and absorb it all and take the plunge!
Download the gbrl software but when trying to install it in arduino I get the message that it does not contain library's. Even deleted arduino and downloaded again. Same error message. Think I need a Dummies book for this.
What you need to do is use XLoader (you could probably use T2Laser too) to upload the .hex file to the Nano.
I guess this is where its nice to have multiple Arduino Nanos? One for Grbl, one for JTech, etc. Then just plug-n-play.
Since having the gantry slow down and speed up (at the ends of each line) with the laser turned on produces an uneven burn, might it be better to have the module already moving before the laser turns on and then running past the end of a line before the module stops? This allows the laser to be up to cutting speed before it turns on, and then finish burning the line before the carriage stops to reverse and retrace for the next line.
You don't have to do this, I don't think. It sounds like all you need to do is adjust your acceleration settings of your Grbl. It sounds like they might be set too low.
You can manually see your settings using different software but in my BenCutLaser (screen shot attached) just go to the com port tab and click the $$GrblSettings link and BCL will ask the controller to send back the current Grbl settings...look at what your values are for $120 and $121. If you don't have or don't want to install BCL just use any software where you can manually send the $$ command.
I use about 400 and if yours is set to under 100 the head will slowly decelerate before coming to a stop and then slowly accelerate back up for the next line burn. A setting of 400 to 500 will give you fast, crisp stop starts which is what you want for lasers...but...make sure your frame is secured to your work bench!
If you "Skip Blank" in T2Laser it will still add a small distance at each end of the travel for this purpose, and obviously without it selected the head scans the entire line just turning on and off as needed.
Increasing the acceleration value helps obviously, but also keeping the max feed rate lower does too as you don't have such a difference.
Sorry, just joined and also purchased an A3 laser engraver. Will need much information to get up and running once it arrives. Reading much of these posts and getting an understanding of what I need to do to get software/firmware talking to the rig.
Ralph, just wondering if I am reading this wrong, but in a few posts above, you stated $120 and $121 should be 50.00, but later on, you say they are set to 400 each. (to get nice crisp stop/start lines). No one commented on this, so maybe they are discussed in other forum locations as to what each line settings should be set to and why.
Welcome to the forum...!!!
$120=400.000 (x accel, mm/sec^2)
$121=400.000 (y accel, mm/sec^2)
$122=400.000 (z accel, mm/sec^2)
Inside BCL there is a one click link that will set all of the Grbl settings for you!