Iv had this trouble with my printer after sanding down the platform to achieve a smooth finish to aid with removing objects printed without a raft. It seems to me that in your case the distance of the platform to the LCD screen is too high due to an incorrect adjustment of the Z axis cut off, (this is set at Zortrax factory, but you can adjust this yourself at home). Your calibration tests are not coming out well because the distance is too large between the screen and the platform, meaning your first layer is huge, soft and nothing will adhere properly to it.
Have your platform in the raised position with printer turned on. If you take a look at the bottom of the z axis screw you will notice a sensor with a red light. This sensor detects when your platform is all the way to the bottom. Calibrating the machine doesn’t change when this sensor activates. A small metal part screwed to your z axis block is what activates the sensor. The platform goes down, the metal part is inserted between the two sensor points and the machine believes the platform is against the LCD screen.
You can adjust this to ensure your platform is actually resting on the LCD screen for its first layer. Carrying out this will bring your platform closer to the screen which will then make sure that objects around the edge of printed more successfully as the first layer will be correct size, and therefore correctly cured.
Heres how I calibrate my Z axis screw and platform correctly.
- Machine turned off
- Tank on with little resin.
- Platform on and pushed down on the screen.
- Now carry out manual calibration while the machine is turned OFF! ie loosen the platform joint, push down on the sides while platform square and flush, now tighten the joint again, all while keeping the machine turned off.
- Turn machine on. Dont move platform by hand.
- In the far right corner of the upper face of the Z axis block, there is a small hole with a grub screw inside. You need to adjust this until the red light goes off (z axis sensor) when the platform is in its bottom position. This grub screw just adjusts the metal part I talked about earlier, which you can see if you look under the z axis block. Note the red light should BARELY turn off, too much and the platform will be too high when the sensor activates during the zeroing of the platform before the print.
Word of warning, if by chance you havnt correctly adjusted this grub screw and even when the platform is at it most down position, and the red light hasnt turned off, the machine will continue to force the z axis down, trying to zero the platform. The machine will make loud noises before sending a error code. You can protect yourself here, by being ready to turn the machine off from the switch at the back in the event of this happening. The only time this will happen is at print start. Simply readjust and try again if you need to.
I hope this helps, if anything is unclear then I can clarify again no problem.