Move the Z after STOP URGENT

Roberto

Hello to all,
For my RailCore II ZTL300.
When I make an emergency stop or come to the end of a print, I can't get the Z down. I have to do an ALL HOMES. It is therefore difficult to remove the part that is being printed without lowering the plate.
Do you have a solution for lowering Z without going through ALL HOMES?
Thank you

o_lampe

@roberto You can use relative moves (G91) and G1 H2 Zxx Fnnnn, which moves the Z axis relative to the current position without checking endstops or homing status

G91
G1 H2 Z20 Fnnnn   ; raises the nozzle 20mm 
G90   ; back to absolute moves

If you have more than one individual Z-motor use Z20:20:20 (for three motors)

T3P3Tony

@roberto said in Move the Z after STOP URGENT:

When I make an emergency stop or come to the end of a print, I can't get the Z down

These are two different situations.

When there is an emergency stop the control board is reset so it does not know where any of the axis are so to move an axis it needs to either home it or use a command like @o_lampe suggested to move without homeing. The other options is to tell the printer roughly where the axis are in order to move Z, e.g. M92 Z50 (tell the printer that Z is roughly at 50mm. then you can jog the printer to increase Z until you can remove the part. After that you must do a Home All to let the printer know where all the axis are.
If the axis are being set to unhomed after a print finished then there is probably a M84, M18 in your end gcode. have a look to see what commands are sent at the end of a print. Also there could be an M0 and then you have M18 or M84 in your stop.g

Roberto

@o_lampe Thank you, I take good note of it. Tonight I will do the test.

Roberto

@t3p3tony Thank you Tony, it is very interesting and I am learning a lot.
I bought 4 RailCore II ZLT300. I will assemble 2 here (Belgium) and the other 2 will go to Africa for a humanitarian mission and students will assemble them there. Your informations is precious.

zapta

@roberto, if it helps, this is a macro file I am using for a similar use case, unconditional raise of the head (or dropping the bed, depending on the printer design). If you prefix the macro file name with a numeric value such as "02_raise z" it will also appear in the PandelDue's main page.

G91               ; relative positioning
M400
M913 Z25          ; Z motors to 25% current
G1 Z30 F2000 H2      ; drop Z by 30mm
M400
M913 Z100         ; Z motors to 100% current
G90               ; abs positioning

A side question, can you share why you chose RailCore for your project? That is, vs other similar designs such as RatRig, or more common printers such as Prusa, or low cost Chinese such as Ender 3.

Roberto

@zapta Hi Zapta, thanks for the macro, I will try to place it.
For the choice of the printer: I am an ortho-prosthetist and I do humanitarian missions in Africa. So I tried several printers. I work with soft materials to make feet and hands and some sockets. So I have to have an extruder with a direct drive. I can't have a platen that moves in XY and I need to have a minimum height of 60cm to print the thighs. I have a CR10V3 to make the feet.

zapta

@roberto, it seems that the main considerations were driven by kinematic (no moving bed) and dimensions (min height). That makes sense.

BTW, are your prints customized per person? In that case, how do you take measurements and create the STL model?

Roberto

@zapta Hello Zapta,
the prostheses are completely personalized.
There are two ways to make the sockets. The technician who is in Africa, take the scan of the patient's stump or with the plaster, he makes the mold of the child's leg, he makes the corrections and then sends it to me by internet. I do the modeling with the software and I set the G-code and I send it to the technician who will print it at home.