Touch Probes & Zeroing

Probing is how you tell the machine where stock is, how flat it is, and how long the tool is. Routers usually want a simple corner-probe block; mills want a real 3D probe; PCB mills need a surface-leveling probe grid; plasma tables need ohmic plate probing. Macro support varies sharply by controller / firmware and sender.

XYZ corner probes (router default)

• ★ Carbide 3D BitZero v2 — paid (~$70); aluminum corner-probe block, alligator clip on the bit. Pairs with Carbide Motion's probing wizard. The "shipped with my Shapeoko" default.
• ★ Triquetra 3D Touch Plate — paid (~$60); USA-made; works with UGS, gSender, CNCjs, Mach3, LinuxCNC via macros. Most-recommended generic XYZ probe block.
• OneFinity touch probe — vendor-specific; works with their Buildbotics / Masso UI.
• Sienci AutoZero / Touch Plate — vendor; ships with LongMills, gSender support.
• Inventables / Easel touch probe — vendor; integrates with Easel.
• Mason Probe — paid; USA-made aluminum block; popular as a Triquetra alternative.
• Generic Aliexpress XYZ blocks — cheap (~$15); fine if your sender's macros line up.

Edge finders (mills, manual zeroing)

• Mechanical edge finders (0.200" tip) — paid, cheap; spin in a collet, tip walks over and shifts when it hits stock. The pre-CNC standard, still useful for one-axis touchoffs on a manual mill.
• Haimer Centro / 3D-Taster — paid (~$300+); analog dial 3D touchoff; the prosumer mill default. Not a probe — you're reading a dial — but it's the gold standard for fast manual setup.
• Tschorn / Insize 3D edge finders — paid; cheaper Centro-class options.

3D touch probes (mills, real CNC probing)

• ★ Renishaw OMP40 / OMP60 / OMP400 — paid, premium ($1500+); the industrial standard. Spindle-mount probes that talk to a separate optical receiver. Used cheap on eBay if you can find them.
• ★ Tormach Passive Probe / Power Probe — paid (~$300 passive / ~$1000 power); Tormach's 3D probes; PathPilot has built-in macros (Probe Screen). The realistic prosumer benchtop option.
• Tschorn 3D probes — paid; mid-range alternative to Renishaw.
• PWB Swiss / Centroid Probe — paid; industrial.
• Mesa BHC + DIY M18 probe — DIY; cheap LinuxCNC-friendly option.
• G38.x probing macros — built into GRBL, grblHAL, FluidNC, LinuxCNC, Mach. Any switch closure can become a probe.

Plasma probing (ohmic / floating head)

• ★ Ohmic probing — uses electrical contact between torch tip and (clean) sheet metal to find Z=0 before each pierce. Standard on Langmuir FireControl and most Mach3+THC plasma builds.
• Floating head + Z switch — mechanical; the torch carriage drops onto the sheet, hits a limit switch. Backup when ohmic isn't reliable (paint, scale, oil).
• Proma THC ohmic — built-in to Proma Compact / Proma Sensor; see Plasma & THC.

Surface probe grids (PCB milling, warped stock)

• ★ bCNC auto-leveling — open source; the gold standard for surface probe grids. Probes a grid of points, builds a heightmap, applies it to G-code at runtime. The reason bCNC exists. Essential for PCB milling.
• CNCjs autolevel widget — open source; lighter alternative.
• FlatCAM — open source; PCB-CAM tool with built-in autoleveling.
• G-code Ripper (Scorch Works) — free; Windows; applies a heightmap from a probe scan to existing G-code. Used a lot for engraving warped wood.
• Candle autolevel — built into Candle (Windows GRBL sender).

Auto-zero macros (controller-specific)

• GRBL / FluidNC G38.2 + sender wizard — every modern sender has a probing wizard. UGS, gSender, CNCjs, Carbide Motion all bundle one.
• grblHAL probing plugin — extends G38.x with G38.6 (toolsetter) and tool-length-offset macros.
• LinuxCNC O-words / NGCGUI Probe Screen / Probe Basic — the LinuxCNC ecosystem's probing UIs; very capable, slightly intimidating.
• Mach3 probing wizards (Vital Systems, Big Tex) — paid plugin land; the realistic Mach3 probing answer.
• PathPilot Probe Screen — bundled with Tormach; the easiest mill-probing UI on this page.

Setters (XYZ for tool changes)

• Toolsetter / fixed Z probe — bolt to the table corner; touch every tool to it after a change. Standard on grblHAL, FluidNC, Centroid, PathPilot, LinuxCNC. Often a $5 limit switch.
• BitSetter (Carbide 3D) — vendor toolsetter for Shapeokos. See Tooling.
• Renishaw HPRA — industrial.

Pick this if…

• First Shapeoko / Sienci / OneFinity, just want a corner probe: the vendor block (BitZero v2 / Sienci AutoZero / OneFinity probe).
• Generic GRBL router, any sender: Triquetra or Mason XYZ block.
• Tormach / PM-25 prosumer mill: Tormach Passive Probe + PathPilot Probe Screen.
• Production benchtop or Bridgeport with budget: used Renishaw OMP40 + receiver.
• PCB milling, single-sided FR-4 always warped: bCNC autoleveling, no question.
• Plasma: ohmic probe through your THC; mechanical floating head as backup.
• Manual or sometimes-CNC mill: Haimer Centro for fast 3D touchoff.