Tool offset not working (RCBugFix) #4182
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Ok this is strange, sometimes the head moves when switching to T1 but only in Y direction. Maybe my "strange" setup has an influence on this? |
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If you're using auto bed leveling it will help if you enable The other thing to check is, where on the bed are you doing the tool change? If you are near the edges, it's probable that the movement during the tool-change is being constrained by the software endstops. Try moving the carriage to the middle of the bed before doing the tool-change and see if it works differently. As I look at the code for if (tmp_extruder != active_extruder) {
float xydiff[2] = {
hotend_offset[X_AXIS][tmp_extruder] - hotend_offset[X_AXIS][active_extruder],
hotend_offset[Y_AXIS][tmp_extruder] - hotend_offset[Y_AXIS][active_extruder]
};
for (uint8_t i = X_AXIS; i <= Y_AXIS; i++) {
current_position[i] += xydiff[i];
position_shift[i] += xydiff[i];
update_software_endstops((AxisEnum)i);
}
active_extruder = tmp_extruder;
SYNC_PLAN_POSITION_KINEMATIC();
prepare_move_to_destination();
} |
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I updated to latest RCBugFix again and tried what you said. Switching extruders does not move the head as it did in previous RCBugFix since RC6 maybe a week ago or so... Also the numbers on the LCD do not change... |
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If I do this with RC6 I switch to T1, numbers on the LCD change, moving to the same spot as before does move the head... |
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Here is my config if this helps:
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Your configuration seems fine to me. But oops! Can you do your logging of The last thing the tool-change is supposed to do is move back to the old position from the updated position, so the newly-active nozzle is in the same spot as the previously-active one. Since there is no move, I expect the leveling correction will be strange. But if it looks normal, then I will have to add more logging code to see what else might be going on. |
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Ok did it, here is the result:
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Alex9779
changed the title
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Ok @thinkyhead I found what causes this issue. The PR was #4010. Reverting both commits of this PR makes it working again... |
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This worries me a bit because that PR got merged 17 days ago... Am I the only one in the community actually testing Marlin on a real machine with multiple extruders and MBL? |
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I think these are the problematic lines: What is I changed it to this: and this made it working. But I have a question, why do you change the Z according to MBL? If you move the new extruder to the same spot then this does nothing, would only make sense if you don't move the nozzle with |
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Aha. I thought you were using Automatic Bed Leveling. That would have given us more logging. But we don't have any logging added to the Mesh Bed Leveling part of |
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I'm changing it to this… #else // !AUTO_BED_LEVELING_FEATURE
#if ENABLED(MESH_BED_LEVELING)
if (mbl.active()) {
float xpos = current_position[X_AXIS] - home_offset[X_AXIS] - position_shift[X_AXIS],
ypos = current_position[Y_AXIS] - home_offset[Y_AXIS] - position_shift[Y_AXIS];
current_position[Z_AXIS] += mbl.get_z(xpos + xydiff[X_AXIS], ypos + xydiff[Y_AXIS]) - mbl.get_z(xpos, ypos);
}
#endif // MESH_BED_LEVELING
// The newly-selected extruder XY is actually at...
current_position[X_AXIS] += xydiff[X_AXIS];
current_position[Y_AXIS] += xydiff[Y_AXIS];
#endif // !AUTO_BED_LEVELING_FEATUREThe |
Because the active nozzle is now at a different XY position (before we execute the move back to the old position). So we need to adjust Z to account for mesh variation. MBL will continue to correct Z (most likely returning it to its previous value) once we move the active nozzle from its current position back to the old position. |
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Ok looks good there are the things I didn't understand ;)... Still remains the question about the Z adjustment... Any thoughts on this? |
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Ok strike some points of my last comment because I wrote and you answered at the same time... |
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Ok I thought about this and I don't get why you calculate the positions you use to get the MBL spot differently than the change for the current positions... |
First, we need to get the "raw" current position that MBL can relate to. So we subtract all coordinate offsets that have been applied: float xpos = current_position[X_AXIS] - home_offset[X_AXIS] - position_shift[X_AXIS],
ypos = current_position[Y_AXIS] - home_offset[Y_AXIS] - position_shift[Y_AXIS];Now, we get Z at the new position… mbl.get_z(xpos + xydiff[X_AXIS], ypos + xydiff[Y_AXIS])…and the Z at the old position… mbl.get_z(xpos, ypos)…and we subtract the Z at the old position from Z at the new position. (Let's say the Z at the new XY position is 0.2mm higher, for our example.) mbl.get_z(xpos + xydiff[X_AXIS], ypos + xydiff[Y_AXIS]) - mbl.get_z(xpos, ypos);We add this difference to the current Z. current_position[Z_AXIS] += mbl.get_z(xpos + xydiff[X_AXIS], ypos + xydiff[Y_AXIS]) - mbl.get_z(xpos, ypos);Now we have Z set correctly (e.g., We had forgotten to update current_position[X_AXIS] += xydiff[X_AXIS];
current_position[Y_AXIS] += xydiff[Y_AXIS]; |
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Sorry this explains what but not why... Why do we need to calculate that stuff to get an MBL correction value for the same spot on the bed? I still think this will never result in a move of the Z axis because the coordinates for the old extruder change, the coordinates for the new change but if you look at this from the bed the new nozzle is where the old was and we have only one mesh for all nozzles so the Z correction value must be the same. In contrast if you do not move with Tx S1. Then the new nozzle stays where is was which is a different position on the bed and thus a different correction value... |
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The position always changes, at first. But it doesn't always move back to the old position. |
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Ok I think I got it, you calculate the Z difference for the new nozzle which is still in the different position. But why do you use home_offset and position_shift to get that positions for which you want the correction value and not just the xydiff values as when you set the new values to X and Y axes? |
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Oh well you are a bit too fast for me, I had a look at the PR and you changed other things too. |
Because MBL only works internally with unaltered positions. If your bed is 200x200, MBL recognizes positions from 0-200. If the coordinate system was shifted by 10 in the X (so your X now goes from 10 to 210) and you didn't un-shift it before querying MBL, you would get the wrong Z, and MBL wouldn't know at all what to do with positions like -10 or 210, which are outside of its mesh space. |
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Ya got it now.... Thanks for the explanations again... |
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Tested it, and seems to work now... |
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This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs. |
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I had a discussion recently about the tool offset and switching tool and got a feature introduced so a tool switch can be done with out moving but as for today's RCBugFix I can't get the machine to recognise the tool offset.
I set the offset with
M218 T1 X28 Y-18and then a switch from T0 to T1 should move the head but nothing happens. Moves after T1 is selected still position the first tool to the given coordinates...Another configuration error of me?
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