Unable to print in centre

Troubleshoot issues with the Tarantula
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noelmm
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Joined: Sat Nov 04, 2017 12:18 pm

Unable to print in centre

Post by noelmm » Sun Nov 26, 2017 7:43 pm

Hi everyone,

I was hoping you would be able to help me. I’ve had my Tevo Tarantula for a couple of weeks now and I’ve been calibrating all of the stepper motors so that when I print a 20mm test cube everything is within 0.2mm tolerance which for now is ok for me.

What I have noticed is that my prints are not printing in the centre of the bed but are offset to the back right corner. I have the 220 x 280 bed size and this is defined within the firmware I am running (The latest Marlin from here https://github.com/JimBrown/MarlinTarantula/).

When I auto home the print head the nozzle sits in the front left hand corner however I have noticed that the print head is 24mm towards the right on the x axis (this is obviously part of the design) so I thought that by entering the following into the firmware this may resolve it #define X_HOME_POS 24 however it appears to have no effect on where the printer starts.

The front of the calibration cube is started at 139mm from the front of the build plate and the start of the edge is 124mm from the left side of the build plate,

I have uploaded a picture here https://www.dropbox.com/s/hepm8v2km42io ... 1.jpg?dl=0 so this can be seen a little more clearly.

have also uploaded a copy of my configuration.h file here https://www.dropbox.com/s/k0r8qj7hhizoa ... ion.h?dl=0 if anyone could take a look and help.

Is anyone able to tell me how to resolve this as I really like the printer but this one small aspect is bugging me and I don’t know how to solve it/

Thanks everyone for your help.

Noel

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royg
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Re: Unable to print in centre

Post by royg » Mon Nov 27, 2017 9:19 am

I think that the key to identifying the cause of this problem is to first make sure that when the printer Homes the X and Y Axes, that the nozzle homes about 10mm in from the front of the bed, and about 10mm in from the left hand edge of the bed.

You can do this two ways; 1) Using the Printer's LCD Control Panel, or 2) Using a program such as Octoprint or OctoPi, which provides you with access to the printer's text terminal.
  • If you're using the Printer's LCD Control Panel, use the menu to execute the "Home All Axes" command. Note: The actual wording might vary a little bit, depending on who's version of Marlin for Tarantula you're using. The nozzle should end up at the front left corner as noted above.
  • If you've got access to Octoprint/OctoPi (or similar software), then you can go into the Printer's Text Console Terminal, and execute a "G28" command. (G28 is the Gcode command for Home All Axes).
If the printer does not home to the correct X and Y Axis position, then adjust the position of the End Stop Limit Switches.

Once you've got the printer homing the X and Y Axes to the correct position, then use the Printer's LCD Control Panel to move the X Axis to the 100 mm position, and the Y Axis to the 140 mm position. The Nozzle should now be at, or very close to, the middle of the print bed.

To do a complete check, move the printer to each of the remaining four corners of the heated bed, 0,0 0,200 280,200 and 280,0.

Once you've got the printer homing correctly and travelling correctly each corner of the bed, you should then be able to print an object (including any brim or skirt) that is 200mm x 280mm in the X and Y Axis sizes.

Hope that info helps.

Regards,

RoyG
Tevo Tarantula - Large Bed - E3dV6 - BLTouch
OctoPi (on a Raspberry Pi 3B)
Cura

buffalo
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Re: Unable to print in centre

Post by buffalo » Tue Nov 28, 2017 6:48 am

Good Morning.

Do you have centered your nozzle and z-probe like here described?

https://github.com/JimBrown/MarlinTarantula/wiki

Maybe you set the offset in wrong point of the firmware (#define X_HOME_POS).

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