Z-axis slow
When using a Z Acme screw with 400 steps/mm the Z movement is extremely slow. Initially I made a mistake and did set it to 1600 steps/mm and then it works at speeds I am used to see (I have another printer working with M8 screws for years now). This behaviour is repeatable, whenever I set it back to 1600 steps/mm z speed is normal.
Changing max z speed, accelerations and othe suggested changes or using development version makes no noticeable difference (and yes - I have changed eeprom parameter between changes).
I can find no reason why firmware set much lower speed at 400 steps/mm compared to 1600 steps/mm. To me it would be natural to get same speed for whatever number of steps/mm while now there seems to be some type of set time involved to comlete a movement.
This item has been discussed several times before but none of the suggestions/explanations I have found have improved or explained the extremely slow z speed. I am sure a change to an M8 standard screw would speed up things but the preloaded T8 screw should be a technically better solution I would like to keep.
Comments
There is allso a Z max feedrate and Z homing feedrate in the software tool under
Z axis stepper motor section under 'mechanics tab'.
currently i have mine set at 30 and 12 respectively, with a 400 step/mm lead screw which gives decent Z speed.
Glad to hear that speed could be OK at 400 steps/mm, remains to find the reason why mine behaves differently.
Speed seems to be the same/similar whether movement initiated from controller, from host buttons or with a G-command.
I already have tried changing Z max feedrate and Z homing feedrate without noticing any major change in z speed. Will try again to verify.
Still I can not see any logic in that speed changes when using different settings of steps/mm.
It seems to me that, If it moves 1 mm in 400 steps and is changed to 1 mm in 1600 steps it would have to turn 4 times faster at any given set speed to move that 1 mm.
You are right, of course, but that also means that the time is the fixed variable and not the speed. If speed is constant then time would be 4 times longer for 1600 steps, right?
Thank's, that might be the root of the problem. I have changed the eeprom param between trials but might have missed it. Or are there values which are not changed between compiles even if eeprom mode is changed?
However i allways prefer to do a
M502
M500
this will read the config.h and store values into eeprom.
When checking the eeprom values I found that these were not correct at all for max speed and homing speed. I do not know what happened because values were not in line with any value I ever did set nor the "standard" values coming from the config tool. After changing them manually with the host software z-speed became OK also for 400 steps/mm. Guess I should have cleared the eeprom before upload of the firmware.
Thank's a lot to everybody contributing to the solution.