How are the knob turns calculated?

Each corner's height difference from the lowest corner is divided by the screw thread pitch. One full turn of an M3 knob moves the bed 0.5 mm, so a 0.1 mm correction needs 0.2 of a turn.

What thread pitch should I enter?

Most printer bed knobs use M3 or M4 screws. M3 has a 0.5 mm pitch (the default here) and M4 has a 0.7 mm pitch. Check your hardware if unsure; the wrong pitch scales every turn count.

What does the tilt angle tell me?

It reports how far the bed plane leans left-to-right and front-to-back in degrees. A perfectly trammed bed reads near 0° on both axes. The angle is useful for spotting a warped or sagging frame.

Why use the lowest corner as the datum?

Bed knobs only raise the bed toward the nozzle, so the calculator treats the lowest measured corner as fixed and raises the others to meet it. This avoids asking you to move a corner past its travel.

What deviation is good enough?

Aim for under 0.05 mm across the whole bed for reliable first layers. Auto-leveling probes can compensate for small residual tilt, but mechanical tramming first gives the mesh the best starting point.

Bed Tramming Angle Calculator

A perfectly level (trammed) bed is the foundation of a good first layer. This calculator turns four corner probe readings into concrete instructions: exactly how far to raise each corner and how many turns of each leveling knob that takes. It also reports the bed’s tilt angle so you can spot a warped frame.

How it works

The tool reads the Z height at each corner from your bed mesh or paper test. It finds the lowest corner and treats it as the datum, because bed knobs raise the bed toward the nozzle rather than lower it. The adjustment at every other corner is simply how much higher it needs to be:

adjustment = corner height − lowest corner height

That distance is converted to knob rotations using the screw thread pitch:

turns = adjustment ÷ thread pitch

An M3 knob has a 0.5 mm pitch, so a 0.10 mm correction is 0.10 ÷ 0.5 = 0.2 of a turn. The tilt angles use the average corner heights on each edge and the bed span: angle = atan2(edge difference, span), reported separately for the left-right and front-back axes.

Worked example

Suppose probing gives front-left 0.00, front-right 0.08, back-left -0.04, back-right 0.12 mm on a 220 mm bed with M3 knobs. The lowest corner is back-left at -0.04, so it becomes the datum. Back-right is 0.12 − (−0.04) = 0.16 mm high, needing 0.16 ÷ 0.5 = 0.32 of a turn to raise it level. The overall deviation is 0.16 mm — above the 0.05 mm target, so one or two adjust-and-re-probe cycles are needed.

Tips

Always adjust corners in small steps and re-probe — the corners interact because they share the same bed plate. After tramming mechanically, run your printer’s auto bed mesh to compensate for any residual warp. If a single corner is wildly out of range, check for a bent bed, loose Y carriage, or a sagging gantry rather than chasing it with the knob alone.