Leveling and Z-Axis offset

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Tshulthise
Posts: 17
Joined: Mon May 20, 2013 11:11 am

Leveling and Z-Axis offset

Post by Tshulthise » Mon May 20, 2013 11:54 am

I own a CubeX Duo and it seems to me that its inordinately difficult to level the platform and accurately set the Z-axis offset. For some reason the bed does not stay level for very long. I also have to reset the z-axis offset every print or two.

It would be easy to design a 3 point leveling system (mechanical, manual) that would allow 2 minute accurate leveling of the bed. with a simple and cheap touch sensor or dial indicator built into the extruder assy. The idea would be to:
1. Flip down a lever with the touch sensor or digital depth gauge on it
2. Touch the table at one of the 3 leveling points and zero the gauge. Three leveling points ensure no teetering. leveling screws should be on easy to access labeled dials or cap head adjusters on the front of the unit. Simple tube in tube flex tubes could accomplish this. The CubeX build plate only moves up and down so if the Lulzbot table moves in x or y then the remote adjusters may not be feasible. They should be easy to access at a minimum.
3. Touch the table at each of the other two leveling points and manually turn the leveling screws until the gauge reads zero.
4. Move the table up until it reaches a calibrated distance from the extruder head to ensure the Z axis offset is perfect for whatever settings are being used for each print. I assume that different z-axis offsets would work better for different layer heights, I'm not sure.
5. Flip the gauge up out of the way before printing.

This would ensure the first pass will stick even for someone without technical skills to truly accurately level the bed. The parts for this can be had from a $15 set of digital dial calipers that have 0.0005" accuracy.

Next level - For consumers that are not capable of or not interested in having to adjust their printer (most of the world, think ... ink jet printer simple) build a closed loop feedback so the system self calibrates before each print. If the resolution/accuracy of the steppers/screws/belts are good enough to remap the g-code so the system will account for slight out of level conditions of the print bed without physically readjusting the print bed, that would be the ultimate no-friction (easy to use even for non technical users) system.

Tshulthise
Posts: 17
Joined: Mon May 20, 2013 11:11 am

Re: Leveling and Z-Axis offset

Post by Tshulthise » Mon May 20, 2013 11:56 am

I suggest using the cheap linear encoder technology since its lower cost for better accuracy than high resolution touch switches. It also would allow more flexibility in various settings than a touch switch would. It may also allow self calibration for various temperatures if that ends up being an issue.

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