Hello It's taken some time to figure out. But I'm loosing z steps, not great but loosing steps, during the course of a cut, something is off. Starting to score and cut deeper than anticipated. Zero the machine, and see I have dropped about a 1/16-3/32"" of an inch. What might cause this? I'm not running a spindle, just a palm router. Running my finishing pass as I type this, set for .003, and not cutting a thing. This was after resetting Z with probe. So it's dropping steps. What to check? Thanks!
check for sticky spots in the travel. remove the leadscrew and move the carriage by hand, fix any sticky spots. while you have it out, check the leadscrew for bends and dings. refit the leadscrew without the motor, turn it up and down by hand, checking for sticky spots. if you can, increase the motor current till it is uncomfortable to hold for 20 seconds after 5 minutes. fit the motor and connect everything properly. Set the acceleration for Z in the controller to half whatever it is now. now run a drilling program, ie a program that makes the Z go up and down a lot (a drill operation with full retracts will do this). check the Z height at the end of the run. if it is still losing steps then halve the acceleration again and set the max speed to 75% and retest and so on. if lower acceleration makes it work then you may want to do some testing on the max speed. you may be able to increase the max speed which will partly compensate for the cut time increase caused by the lower acceleration. acceleration and max speed are always a tradeoff, more of one is less of the other. you have not mentioned what drivers you are using. if Blackbox then ignore this. if some other driver then check the spec sheet. some drivers require a delay between changes in the direction pin and changes in the step pin and getting it wrong can lead to lost steps which no amount of mechanical tuning will fix, the controller has to 'get it right'.
This is a black box controller build. Just testing fit and tightness everything looks good, but I’ll take it down to test further. I have a cut with lots of z movement too. I’ll see how that goes. Inch guy. My step down is at 30 in/min.
If you never turned the z axis pot current up then that’s probably all it is. like Dave said if your motors don’t get at least warm, turn the current up! Gary
Sounds good, I'll give that a try. Not in front of it right now, work... But this is an Open Builds Control and Blackbox build? I'm assuming the setting are in control? I'll check the website. Z Axis looks good, did not take it apart yet. But travels by hand really well.
OpenBuilds BlackBox 4X Documentation So found this in the Black Box Doc. I'm sure most are already aware of it...but just to close the loop in the thread. I'll use a best guess approach to increasing current and run some tests.
Gary, just missed you post.. Thanks a bunch, do appreciate it, thanks David. I'll make adjustments and report back!
1) Adjust current as above 2) Also make sure $1=255 in Grbl settings 3) Double check that bit isnt pulling out of collet during a cut. Had an issue like this a while back - accidentally got some 6mm shaft tooling in my box, and it fits into 1/4 collet quite good... but not good enough, just doesn't clamp it in tight enough. The downforce from the flutes was enough to pull it out ever so slightly as time went on until one day it pulled it out fast enough that it properly crashed and I realised what was happening
