Just built the Sphinx 55 and all is working. However, when I run the "Hello World" file as a test, the Z axis is driving down about 4mm on each pass instead of one. Is this a problem with the Sphinx 55 setup parameters or is there a known configuration step that I just missed? Already cost me one bit - would like to keep the rest of 'em
Hi @Zeph, I'm anticipating questions grbl experts are going to ask - what are your grbl settings? What controller are you using? This thread might help as it gives details of the settings someone else used. Sphinx GRBL settings Alex.
Is this the same when jogging? I.e. just running 1mm up and down by hand. I B once hade a problem when it would lose steps when moving up. This was due to my drv8825 drivers overheating. I would double check the microstep settings on the driver and verify that it matches the expected step/mm in the grbl config.
OpenbuildsCONTROL > Grbl Settings tab > scroll dowm to $102. Check value. 199.1 usually (1/8th microstep as default on BlackBox, adjust or use the provided calculator button to the right if you are using something different) That gets you in the ballpark Then fine tune OpenbuildsCONTROL > Wizards and Tools > Calibration Wizards Steps per mm for Z value probably just off. Check with Jogging before running job again, if you jog 10mm is it moving 10mm etc
I'm using the BlackBox and the $102 setting is 199.100 (same for x and y axes). I'll run the calibration wizard today and see what happens. Thanks for the quick reply!
Hi Alex, I'm using the BlackBox controller and my grbl settings are at 119.100 for x, y and z. I haven't yet run the calibration wizard - I'll do that today and see if it makes a difference. I'll update the OP when I'm finished. Thanks for the quick reply!
UPDATE: Ran the calibration wizard for the Z-Axis using a marking knife on the aluminum and my digital caliper...accurate at 50mm of travel to within 1/100mm...wow! I also tried something else to learn more about what's happening. I set up a piece of material, zeroed out the machine on the lower left corner, removed the material and did a dry-run on the Hello World g-code. I noticed that on each of the letters, every time the z-axis moved down to cut into where the material would have been, the lead screw was turning further and further, making a deeper cut - it was not returning to the same position each time as it should to keep the cuts at the same depth. I checked the flatness of my spoiler board and it's flat to less than 1/2mm in all directions, so that's not the problem and I also checked the squareness of the gantry to the spoiler board and it's darn near perfect. Any ideas on what I should look at next? Thanks in advance!!
I had a similar problem. In my case the cause was that the lead screw was slipping in the pulley. Since the lead screws at slightly undersized at 7.8mm it’s hard to clamp them properly. I added some shims (aluminum from a soda can). This made the clamping a lot better.
Sorry for the delay - life intervened I checked the pulleys and all is good. I'm thinking it's either the motor or the driver as it only happens under load (jogging is fine). Is there a diagnostic some where that I can run on the board or do I just start working with support to replace items until it works?
Its very unlikely to be the board, but easy to test, just swop Y1 and Y2 plugs with each other, if Y2 is still acting weird it proves the board is fine, and either Y2s wiring, or mechanical is at fault. Intermittent wiring also causes issues like that (dont just check the wiring, redo it, making sure wires are solid under every screw terminal and no pinched insulation, etc)
Thanks Peter - will try that and get back to the thread - was thinking the same thing, but thought I'd see issues with jog as well if the wiring was bad. Best to check though
Could it be heat related? Perhaps generate a piece of gcode that simply moves z up and down for a minute.
Thanks Andreas - I'll try that too. Don't think it's heat related as the issue happens almost immediately (on the first two letters of the "Hello World" project). But I won't leave any stone unturned - thanks for the advice!!
Thinking a bout more about the issue. Perhaps it is only triggered when there are more than one axis moving at the same time? I.e. generate some gcode that moves in x+z and y+z at the same time.
Hey Peter, Sorry it took so long for me to get back on the forum - injured my back and been out of the shop for a while. Got back in the other day and checked all the wiring for the Z axis motor. I checked the connections, continuity and for short circuits. All is fine. I did notice something, however. When the Z axis is stationary and the motor is fully energized, it is fairly easy to turn the lead screw. I checked the other axes and they are almost impossible to turn when energized. Is there a schematic I can use to check the voltage/amperage or is there another route I should take? Thanks! Bob
Sounds like a good clue. Does the motor turn when you then the lead screw or does it slip? If it’s not slipping then it sure sounds like an electrical issue. But unless the amps are extremely low it should have a fair amount of holding torque.
Thanks for the quick reply Andreas - the motor is turning - I checked and rechecked the lock collars and they're all very tight. Do you know of any schematics or spec sheets that I can use to trace the circuit and see exactly where the issue is? Thanks!! Bob
This might be a reach, but is the current level set too low for that axis driver, it might be worth checking the setting for the Z axis potentiometer to see if it might be set too low.
Just hit the potentiometer on the front with some tiny screw driver action. Too far clockwise and it might overheat, but check where it is first (too far left, and you won't have enough amps)
First off - I want to thank everybody who offered advice and recommendations - this is an awesome forum and I really appreciate all the assistance! Especially, I want to thank Andreas - his solution from October 1st was actually what I needed. I had checked it at the time, but, as it turns out, old man winter needed to cause a little metal shrinkage before I realized that was the solution...I went into the shop when it was cold to try the Hello World program again and noticed right off the bat the the Z axis was stuttering as it tried to home. I saw that the gears up top were spinning, but the carriage wasn't moving smoothly. I tightened both gears as much as I could and saw that it was still stuttering under load (worked fine with no router installed). I cut up an aluminum soda can and slipped a small shim in between the gear and the lead screw, retried and everything worked fine. Would love to see a couple of real shims added to the build in case of this happening to somebody else. Again - Much thanks to everybody! Now I need to get moving on some really neat Christmas presents!
