I3 Z Limit Chock Block by jimb15122

Last crawled date: 3 years ago

"One less thing - That's good" - My favorite Forrest Gump quote!
This block can be used to lock-in your Z-limit switch height. This eliminates a critical variable which is the second most likely cause of needing frequent bed re-leveling. (read on for the primary cause and solution).
The block is a 10 sided irregular polyhedron, with the unique property that the opposing faces are each a different dimension. In this case, the five opposing sets of faces provide spacing of 22, 23, 24, 25 and 26 mm. Just turn the block to the size closest to what you need, and slide it under the Z limit switch. Then re-tighten while pressing the switch against the block. Use the bed screws to fine tune the level.
If you need different sizes, just scale this in your slicer before printing.
So what is the actual primary cause of frequently needing to re-level the bed?
The cause is: Loss of Z rod synchronization. This happens when one of the Z rods turns when the other does not. This often occurs when changing filament, due to the large amount of downward force needed to compress the extruder spring. It can also happen if one Z stepper skips and the other does not.
The fix:
Turn off the printer or disable the steppers.
Use a real level to verify that the x carriage rods are perfectly level (or even better - match the level of the table the printer is on!). Manually turn the Z rod collars until perfect.
Make a small mark on the very front of each Z-screw collar. (see second photo)
Perform a normal bed leveling. During the process, make sure the marks on the collars stay in sync. (relative to each other). Take time to be precise, because this one should last a while.
From this point on, all you need to do is make sure the marks are in the same clock position before starting a print. You can also just turn them both to 6 o'clock. It is best to turn the Z rods while the printer is off or the steppers are disabled.
It is especially important to re-sync the Z rods after changing filament.
During brim or skirt printing, observe the bead. If you need to raise or drop the bed, turn all 4 bed screws by the exact same amount. I use a screwdriver with a easy to see mark on the handle to keep track of fractional turns.
By using both of these techniques, I have been able to forgo the complexity of adding an auto bed leveling system.
P.S. If you found this useful, then please check out my new product The "OFFi" Auto-off switch for ANET A8 at: http://www.ebay.com/sch/i.html?_nkw=jimb15122
Thanks
JimB15122
Inventor of the original "Stiffi" x axis bracing system.http://www.thingiverse.com/thing:1985444
"Try to solve the real problem, in the simplest way possible."