Hi all, I would need a little assistance guys to clear up a couple of questions I have concerning GRBL settings on my 750x750 WorkBee running the X-Pro v3. I've been trying to calibrate my cnc machine, but to the life of me I can't work it out I recently installed 'Grbl Panel version 1.09.18a'. You'll see that my X and Y axis' have -3.003' as my machine home positions, my Z axis remains as -3.000 I understand that the -3.000 is the 'pull-back' from the limit switches .............. that's not the problem. The problem is the 003 at the end!? >> When I calibrated my X and Y axis' ( Z was fine ), I changed the stepping from $100=200 to $100=199.500 on the X axis, did the same for the $102=199.500. As per the instructions ............. and the tutorials on YouTube >> I didn't do the calibration by the recommended means, I used a ruler! currently I don't have any material to cut. Basically, what I did was to run a V-Carve bit along a metric ruler ( as I'm in France ). I jogged the machine 300mm, it ended up at 302mm, this told me that the stepping was too high, so I gradually reduced the stepper motor travel til I got what was needed. At 199.500 I get an exact 300mm travel, so that method worked OK, even though it's probably not the correct way to do it. What I'm concerned about is, is the 3 at the end ................ it should read -3.000 But it's impossible to zero it out! Any ideas? TURK
Probably not Alex, but I like to be exact. If it should show zero, then there should be a way to zero it out. It only showed up after I adjusted the stepper motors to 199.500 TURK
Your machine (stepper motors) move in Steps, not millimeters. As such grbl moves to the nearest step (physically smallest motion your machine can make) and it may be 1/5th of a hair away from where you want it but that is the limitation of the physical resolution of the machine. It all averages out over the course of a job 199.5 steps per mm, half a step is impossible too so Grbl will move 199, and 200 respectively to average that out too
Oh and I've been there (; - the wife probably has a cutting board that you could VCarve something on hehe - the old kids toys forgotten in the box in the hall cupboard has some wooden blocks (; - any old wooden jewelry boxes around? - look in the garage - we've seen people lasering on Cookies because the itch struck while the stores were closed - 'materials' come in many different shapes than just sheetgoods
Sorry, my bad ................ I explained that very badly! But I did mention that I 'reduced' the stepper motor travel, that's what I meant. I followed Ooznest' Howto on YouTube "How To Calibrate A CNC Machine Running GRBL Firmware", as best I could. I only substituted his material to a ruler for the time being. He goes on to show a rather complicated calculation ( formula ) to change the setting in $100 and $101. And he does import fractions! and I've seen this elsewhere as well. Example in Ooznest' tutorial: $100=199.38 And now that you mention it, and having looked at Ryan's tutorial again ................ I may of got the decimal point wrong I'll take a look at that again tomorrow, as it's the middle of the night now, here in central France. Thanks for your help guys. Much appreciated TURK
Measuring actual travel with a pointy tool and a rule is how I do it - if you measure a cut in material you are introducing other variables (eg backlash, tool deflection) that need different solutions. Alex.
I agree Alex And using a micrometer or calipers my be just a tad over the top. The V bit I'm using is the smallest one I could find, 3.175 mm shank to needle point tip! Originally, I was going to use this website to calibrate my machine, but didn't know what to put in the boxes > CNC Axis Setup and Calibration | Tools | xix xeaon The 'Lead Screw' field had me stumped for a while, but I take it as I have the WorkBee with an 8mm lead screw, that's what I put in there. Micro-Stepping/Step Divisions .............. Don't know!? I assume that's the amount of rotations on the lead screw for a full rotation of 360° Don't know how to work that out! 'Degrees Per Step' ...... that's easy, it's written on the stepper motors themselves! Shame, could of been a handy tool. TURK
It's easy really - make a note of your current settings - jog the machine a specific distance (the longer the better because our leadscrews are made by "hot-rolling" the thread form into a bar, and they are not necessarily exactly uniform along their length) - divide the actual distance moved by the distance you told it to move - multiply your current steps/mm by the answer and put the result in your grbl settings. Re-test, but if it still isn't spot on remember you now have a new value for steps/mm. Also, it's a good idea to repeat the measurements a few times to make sure that you are getting consistent results before you change your grbl settings. Hope that makes sense. Alex.
Microstepping is also easy to figure out. Look at the jumpers on your board. Its set to 8 from the factory. More info in the xpro wiki "Motor turns, but travels way too much or too little" : Spark-Concepts/xPRO
OK, thanks guys, I'll take a look at that tomorrow. At least now I have something to go by. And yes Alex it's a little clearer now. I had been doing this for a few days now, reading everything I thought may be appropriate to what I was doing, and looking at YouTube videos of people doing the same thing as I was ............. not always the same though, different machine, different setups. In the end I think I confused myself! I guess I'm really as dumb as I look then! I'm currently looking at Vectric software ........................ got all confused there as well! Seems as though I almost made a very big mistake by buying the wrong version! My heart was set on the 'Cut3D' version of their software. Until I just learned that it's not actually an 'upgrade' or the next level up from 'Cut2D', but a very different thing altogether. But that's for another thread another time TURK
