An introduction and a small query/question

Good morning, afternoon, evening depending on where you all are, here it is nearly midnight and after many hours playing with my new toy i am slowly starting to get it working somewhat correctly.

Wanted to try out CNC/Laser engraving but finances wont stretch to a proper/decent machine so have started off with one of the chinese 3018 type. i have seen many videos about these and everyone seems to start spending money on upgrades the minute it arrives so i purchased what i believe is a better model, all alum construction, no 3d printed parts, 300watt motor, 30 watt diode laser (yes i know thats the chinese rated input power) 16mm guide rails, 6 limit switches, proper power supply not the brick type.

i am a complete beginner to this but am capable of walking and talking at the same time so not a complete idiot. I think i have managed to sort out the user,absolute, origin, homing, offset thingy settings and the machine seems to return to a safe position when i click HOME but after a bit of code completes the machine was moving passed the home point and crashed into the limit switches.

6 hours yesterday trying to figure out why this happens and then i found the RETURN TO FINISH POSITION button and the figures did not match the home position. Another 6 hours today trying to resolve why the machine does not home on power up, have double checked the device settings (the bit you go through when you first setup/connect) and the AUTO HOME YOUR LASER ON STARTUP is checked/switched on.

so after a lot of waffle my question is …is this

(1) a chinese 3018 problem
(2) an ID 10 T problem ie ME or
(3) a lightburn setting that i have not yet found.

If the answer is 1 i’ll live with it, if its 2 i’ve been called worse i’ll live with it, if it’s 3 can someone please point me in the right direction it would be nice to have it function as its one less thing to have to think about when i startup, many thanks in advance to any help/suggestions

Start with this post and let us know if you’re still having trouble.

If it homes properly when you click the ‘Home’ button, it should home on startup as well, if you have that toggle enabled.

The offset from the home position might be because you have a CNC machine configured to use a laser. GRBL by default homes to the rear-right, and sets itself to negative workspace after homing, which means you need to set an offset from the homing location to the front-left origin. The link Rick provided above includes how to set up that offset, and the $10 setting that you might need to make that work.

Good morning, thank you very much for all the info/suggestions. Everything in your suggestions had been completed/changed/reset and the settings for Negative coordinates as per this help page had been actioned, but lo and behold I Powered up the machine, computer & Lightburn this morning and the machine homes as it should. The only thing i did not do yesterday was to completly shutdown and restart everything. i apologise for wasting your time.
Could you point me to somewhere that explains the STEPS PER … MM, as the reply from Rick states “most of the 3018s have their motor stepping rates set very high 800…1600” . mine reports that it is 400, everything is working so its not a problem but i would like to understand this more. Thanks again for your time and effort.

Hi, I’ll try to explain: steps per mm is the value, that defines, how many electric pulses are needed to move the head 1mm in the axis. Every stepper motor has defined amount of steps to rotate the full round. This is done by electric signals (usually 3 wires, which spis 3 magnet circles inside motor). The axis of the motor is transmitted to the axis through some wheels (or screw curve, or another type. sorry for my english), which define the ratio of the pulses needed to move with the head 1mm distance. If you don’t know the exact value, the simplest way to figure it out is to setup some “circa” value, than move any known value (100mm for example) and then measure the actual distance the head travelled. This gives you the actual ratio for the value correction.

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In addition to what Ondrej says above, 3018 machines are driven by lead screws. The stepper motor must turn the screw a certain amount to move the cutting head, and the “steps per mm” value is adjusted for this, as well as any partial or fractional steps provided by the motor driver (micro-stepping).

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