Z speed issue after updating Host to version 84

I updated to version 84 and now I have a speed issue with the Z axis.
When I send it to the home position it moves very slowly in the positive direction and than blasts home.
Previous to the upgrade everything was working fine.
Any advice would be appreciated.
Rick

Thought I'd try again as I'm still having the same issue.
Everything was working fine until I updated the host and firmware.
When I open the host and connect to the printer my X and Y axes work as they should. They move at a constant speed in the positive direction and when I hit the home button they move at the same constant speed to the home position.
My problem is with the Z axis. When I move the Z axis in the positive direction it also moves at constant speed. The issue is when I hit the home button. It moves extremely slowly to the home position and once there it moves extremely fast when it retracts and returns home. It's so fast you can't see it change direction.
I used all the previous firmware version basic settings and didn't make any changes to any axis speeds.
I'm not sure what paramaters I should try changing or what values I should change them to.
Any advice would be greatly appreciated.
Thanks,
Rick

This is clearly a problem in the firmware. The home commands do not contain any speed settings.

If the main move speed is ok, you should check this part:

// For higher precision you can reduce the speed for the second test on the endstop
// during homing operation. The homing speed is divided by the value. 1 = same speed, 2 = half speed
#define ENDSTOP_X_RETEST_REDUCTION_FACTOR 2
#define ENDSTOP_Y_RETEST_REDUCTION_FACTOR 2
#define ENDSTOP_Z_RETEST_REDUCTION_FACTOR 2

it divides the speed for the retest. Values < 1 would do the opposite and increase the speed. That's the only reason I can think of at the moment matching your description.

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Thanks for the reply.
I was finally able to try your suggestion.

With all settings at the default 2:
Starting with the extruder in the x,y,z home position I homed x & y and they worked as they should.
I raised Z to 10mm and it moved at a steady pace as it did before the update. I than moved it down 10mm and it moved at the same steady pace as it did before the update.
Next, with it in the home position I hit the home button. It seems to reset the home position 1 or 2 mm above the end stop position. The first time it moves very slowly down about 1/3 of a turn until it activates the end stop, than up extremely fast and stops above my end stop switch home position. The next time I hit the home button it moves extremely fast up and than extremely fast down again stopping above my end stop position.
Next I moved it up 5mm and it worked fine. When I homed it it moved extremely slowly down, than extremely fast up stopping above my end stop position.

When I change the Z setting to 1:
When I manually raise and lower Z it moves as it should.
When I manually raise and than home it it moves extremely slowly down to the home position, than extremely slowly up and extremely slowly down again to the home again. This time all home positions are the actual end stop positions.

I'm at a loss as to what needs to be changed in the firmware. I know you said the home commands have nothing to do with speed settings but the Z home button is the only one that's giving me a problem.

Thanks again for any help.
Rick

I forgot to include that when I updated the host I also updated the firmware.

Edited 2 time(s). Last edit at 03/08/2013 07:30AM by Flyer2.

I seem to be the only one having this issue.
Can anyone offer some other specific settings I should check?
What I don't understand is when I change the retest reduction factor from the default 2 to 1, rather than speeding up the movement actually slows down to a crawl in both directions. And with it at the default 2 factor the home position is above the mechanical end stop position.
Anyone?
Please?
This is extremely frustrating.
Thanks,
Rick

Hi Rick,

what version are you using? If you are using 0.80 or higher make sure you have changed the feedrate to mm/s from mm/min in previous versions. If you have a look at the homing function for z in Commands.cpp:

  if(zaxis) {
    if ((MIN_HARDWARE_ENDSTOP_Z && Z_MIN_PIN > -1 && Z_HOME_DIR==-1) || (MAX_HARDWARE_ENDSTOP_Z && Z_MAX_PIN > -1 && Z_HOME_DIR==1)){
      UI_STATUS_UPD(UI_TEXT_HOME_Z);
      steps = (printer_state.zMaxSteps-printer_state.zMinSteps) * Z_HOME_DIR;         
      printer_state.currentPositionSteps[2] = -steps;
      move_steps(0,0,2*steps,0,homing_feedrate[2],true,true);
      printer_state.currentPositionSteps[2] = 0;
      move_steps(0,0,axis_steps_per_unit[2]*-ENDSTOP_Z_BACK_MOVE * Z_HOME_DIR,0,homing_feedrate[2]/ENDSTOP_Z_RETEST_REDUCTION_FACTOR,true,false);
      move_steps(0,0,axis_steps_per_unit[2]*2*ENDSTOP_Z_BACK_MOVE * Z_HOME_DIR,0,homing_feedrate[2]/ENDSTOP_Z_RETEST_REDUCTION_FACTOR,true,true);
#if defined(ENDSTOP_Z_BACK_ON_HOME)
      if(ENDSTOP_Z_BACK_ON_HOME > 0)
        move_steps(0,0,axis_steps_per_unit[2]*-ENDSTOP_Z_BACK_ON_HOME * Z_HOME_DIR,0,homing_feedrate[2],true,false);
#endif
      printer_state.currentPositionSteps[2] = (Z_HOME_DIR == -1) ? printer_state.zMinSteps : printer_state.zMaxSteps;
    }
  }

You see only homing_feedrate[2] and homing_feedrate[2]/ENDSTOP_Z_RETEST_REDUCTION_FACTOR are used. You could add a print command to see what speed is used in your case:

OUT_P_F_LN("Z homing speed:",homing_feedrate[2]);

You could also expand in motion.h

void move_steps(long x,long y,long z,long e,float feedrate,bool waitEnd,bool check_endstop) {

into

void move_steps(long x,long y,long z,long e,float feedrate,bool waitEnd,bool check_endstop) {
if(z) {
OUT_P_L("Z-Steps:",z);
OUT_P_F_LN(" Feedrate:",feedrate);
}

To see with which speed the move is executed in the call. Perhaps that sheds some light on your mysterious speeds.

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Me again,
Thanks again for the reply- I haven't been able to put as much time into the printer lately.

My setup;
ATmega 1280
Ramps 1.4
Host .84
Firmware .81
Skeinforge

I see the homing functions in commands.ccp and I appreciate what you suggest I should do but in all honesty I'm leary of making these additions as I'm not sure where to add them in the code or where to see the result (Host log?).

Regarding the retest reduction factor the only way I can get the Z axis to work is with it set at 1. The Z axis works at the same steady rate when homing and retesting and maintains the home position at the mechanical endstop.

With the factor set to anything other than 1 (1.1, 2, .5) the Z axis moves at a steady rate until it trips the mechanical end stop, than moves extremely fast to roughly 0,0,2 and stops. Doesn't return to 0,0,0. At times it makes the 0,0,2 position the new home position.

I've found a couple of new wrinkles.
I noticed that my Z axis is out of calibration by roughly 20%. Nothing has changed with my entries- I have it set to 2200 steps per mm in the EEPROM as it always has been. What I have found is that any changes made to the Z steps per mm affects the Z feed rate and that the amount of change in the feed rate is directly related to the amount of change to the Z steps per mm setting but it's especially noticeable when lowering the Z steps. For whatever reason 2200 seems to be somewhat of a base setting.
When I set it to 2190 the Z feed rate is less than half of what it was at 2200 (which isn't very fast).
When I set it to 2180 it becomes extremely slow- so slow you can see the steps.
At 2177 it barely moves.
At 2176 it moves as if I changed the reduction factor only now it moves extremely fast to the mechanical end stop, than extremely fast to 0,0,2 and stops.
When I add to the 2200 base setting the Z feed and homing rates increase but they always return to the mechanical home position. So if I start at 0,0,5 it moves to 0,0,0, than 0,0,2 and back to 0,0,0. However, the Z feedrate gets faster and faster as the number increases. I tried 2250, 2300, 2350, 2400, 2450 and 2500 and the movements were correct- they were just increasingly faster but always returned back to the mechanical end stop home position.
I haven't tried printing with a higher setting to see if it actually changes the actual print height- will give it a shot tonight.

As far as the Z homing feed rate value it's set as 30 in the firmware and EEPROM. When I changed it to 25 and than 35 I got the extremely fast movements and incorrect home settings.

Last, for some reason when I try to run a sketch now the initial move to the position where it should start printing the skirt involves an extruder retraction that gets larger each time I run the sketch. The very first time I run the sketch it extrudes as it should, but each successive run makes the amount of the retraction larger and larger. I've checked my firmware and skeinforge settings but don't see anything that should be causing this. I also checked the start g code file and there are no movements related to the extruder.

So I'm at a loss. The reduction factor isn't working, Z steps per mm affects feed rates, Z homing rates can't be adjusted and I'm getting an incorrect extruder move. I've tried downgrading both the host and firmware but even the old versions that were working fine before no longer do.

I hope someone can help me out. Thanks in advance,
Rick

Edited 1 time(s). Last edit at 03/25/2013 05:44PM by Flyer2.

You mentioned the solution in your last part. Feedrate30 ismuch too high. I can only go 4-5 mm/s. The 30 comes from an other printer without z rod. Reduce it to 3 and set z steps to 2560 for M8 rods and everything should work.

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Thanks Rep,

I made the changes and when I try to run a sketch and it moves to position to start the skirt the filament retracts completely out of the extruder. Any suggestions?

There are 2 possible reasons I can think of:

1. You didn't reset extruder with G92 E0 and it was on a higher position before from a previous print
2. Relative extrusion without saying it to the printer (Skeinforge does that).

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Can't thank you enough. I made all the changes you suggested and it seems to be working much better. Adding the G92 command to the start code solved the retraction problem at the beginning of trhe print but now it does the same thing at the end of the print. Only now it probably makes 10 complete revolutions before stopping.

Would a G92 end code do anything?

Thanks again for the help,
Rick

edit- think I figured it out. Wrong command.

Edited 2 time(s). Last edit at 03/26/2013 10:24PM by Flyer2.

At the end you need to find the source gcode line for that. G92 helps only if it is at the right place. Normally this does not happen, so I guess it is in your slicer end code or repetier end code. My guess is when the code was added it should retract 2 mm but beeing in e.g. absolute mode -2 means position -2 and if the print is at 400mm it will revert 402 mm.

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