Fixtures
Custom End-of-Arm Tooling Plates, Machined to Print
The plate between the robot wrist and the gripper, drilled to both patterns and kept light enough not to spend your payload.
An end-of-arm tooling plate is the machined adapter between a robot wrist and whatever the robot holds: grippers, vacuum cups, sensors, a tool changer. It carries the wrist bolt pattern and locating boss on one side and the tooling pattern on the other, dowelled so a rebuilt tool returns to the same point. Thickness and pocketing are a payload decision. Send both patterns and the tooling layout; a person quotes in 24-48 hours, standard lead time 4-6 weeks.
Updated September 2026
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Commercial work only. We don’t quote firearms, DoD, ITAR, or EAR-controlled parts.
Two patterns, one plate, and a locating feature on each side
The plate has a job on each face. On the robot side it matches the wrist mounting pattern: a bolt circle, a centre boss or counterbore that locates the plate concentric with the wrist axis, and usually a dowel or keyway that sets the rotational position. On the tool side it carries whatever the cell needs, and that pattern is yours. Get either one wrong and the tool is out of position in a way no program offset fixes cleanly.
So both patterns belong on the print as dimensioned features referenced to the same datum, with the fit class on the locating boss and the dowel holes stated. Robot makers publish the wrist pattern in the mechanical section of their manuals, and the safest thing to send is that page alongside your model. A tool changer between the two shifts the question but does not remove it: the plate then matches the changer’s tool-side pattern instead.
Payload: why the plate is pocketed and not just plate
Every ounce on the wrist comes out of the robot’s rated payload, and it comes out twice because mass hung far from the wrist also raises the moment the robot has to carry. That is why EOAT plates are pocketed, ribbed and cut away rather than left as solid plate: the stiffness is kept where the loads run, between the wrist pattern and the mount points, and the metal in between is removed.
Aluminum is the usual answer for the same reason. 6061-T6 covers most plates; 7075 earns its cost where a thin plate has to stay stiff under a long reach. Steel appears only where a small, heavily loaded detail needs it. Tell the quote the payload budget and the robot model, and the pocketing can be drawn to it rather than guessed at. The laser-cut robot plate page covers the flat, cut-profile version of the same part when no machined features are needed.
Flatness, dowels and getting the tool back after a crash
Two things keep an automation cell repeatable: the plate is flat enough that bolting it down does not twist it, and everything on it is dowelled so it returns to position after it comes apart. Both are worth calling out. Flatness and parallelism belong on the print for the mounting faces, and every gripper, cup mount and sensor bracket that must return to the same place gets two dowel holes with a stated fit class rather than relying on clearance bolts.
That matters most the day a cell crashes. A dowelled tool comes off, gets inspected, goes back on and runs the old program. A tool located only by bolt clearance has to be taught again. Cast tooling plate is worth it where flatness carries the datum: the MIC-6 brochure (howardprecision.com/wp-content/uploads/2017/08/Mic-6-brochure-1-1.pdf) gives 0.005 in maximum deviation from flat on plate 3/4 in and thicker, and ATP-5 (public.vistametals.com/products/atp-5-precision-tooling-plate.pdf) guarantees 0.005 in over 0.500 in thick.
What else ends up on the plate
EOAT plates are rarely just plates by the time a cell is running. They carry tapped holes for gripper bodies and sensor brackets, clearance and counterbores for cap screws, dowel holes, cable and hose routing slots or tie-off points, through-holes for vacuum lines, pockets for a valve manifold or a sensor block, and often a cutaway so a camera can see past the tool. All of that is ordinary CNC milling work once it is on a print.
Vacuum tooling adds one more: a plate can be drilled and ported so the vacuum runs inside it to each cup location instead of through external tubing, which is tidier and less likely to snag. Say if that is wanted, because it changes the plate from a flat part with holes into a part with an internal circuit, with the sealing and port sizes that go with it.
What to send for an EOAT plate quote
Send the STEP model and a PDF print with: the robot wrist pattern or the manual page it comes from, the tool-side pattern and the components it mounts, the locating boss and dowel fit classes, flatness and parallelism on the mounting faces, plate material and thickness, the payload budget and the robot model, any internal vacuum porting, and the finish if the plate gets one. Any file type is accepted and STEP plus PDF is ideal.
If the tooling layout is still moving, say what is fixed. The wrist side is almost always settled long before the tool side, and a plate can be quoted with the wrist pattern held and the tool pattern named as the open item, so the quote reflects what is actually known. No design service is offered here and none is implied: the plate is made to the print you send, and the quote lists what is missing before a build-to-print number can be given.
Inspection, cell sets and lead time
Every plate is checked against its print before it ships: hole sizes with pin gages, hole position by CMM where the print calls it out, thickness with a micrometer, flatness and parallelism on a surface plate where specified, and tapped holes with a thread gage. What cannot be checked as drawn is flagged in the quote rather than shipped unchecked.
One plate is a normal order and there is no minimum; a cell set, or a duplicate plate held as a spare so a crash costs an hour instead of a week, is quoted alongside it and made from the same setup. Standard lead time is 4-6 weeks from approval with the quote back in 24-48 hours, and rush at 1-2 weeks is quoted when a runoff date is fixed, and extended is 6-8 weeks when timing is flexible. Integrators building whole cells will find the rest of the range under robotics and automation parts.
Questions
Before you send a job.
01 What do you need to match the robot wrist pattern?
The bolt circle and hole sizes, the locating boss or counterbore diameter with its fit class, and the dowel or keyway that sets rotation, all referenced to one datum. The safest thing to send is the mechanical page from the robot manual alongside your model. If a tool changer sits between, send the changer’s tool-side pattern instead.
02 How thick should an EOAT plate be?
Thick enough to stay stiff under the load and the reach, and no thicker, because mass on the wrist spends payload twice: once as weight and again as moment. Plates are usually pocketed and ribbed so stiffness stays between the wrist pattern and the mount points. Give the payload budget and the robot model and the pocketing can be drawn to it.
03 Should the tooling be dowelled or just bolted?
Dowelled, wherever it must return to the same place. Two dowels with a stated fit class per component mean a tool that comes off after a crash goes back on and runs the old program; bolt clearance alone means teaching it again. Call the dowel scheme out on the print.
04 Can vacuum run inside the plate?
Yes. A plate can be drilled and ported so vacuum reaches each cup through the plate instead of external tubing, which is tidier and does not snag. Say so with the order, because it turns a flat part with holes into a part with an internal circuit, with port sizes and sealing to call out on the print.
05 Do you design the end-of-arm tooling?
No. The plate is made to the print you send, and the quote lists what is still missing before a build-to-print number can be given. If the tool side is not settled yet, the plate can be quoted with the wrist pattern held and the tool pattern named as the open item.
06 Can I order a spare plate at the same time?
Yes, and it is worth doing. A duplicate made from the same setup turns a crash into an hour of downtime rather than a rebuild, and it is quoted alongside the first plate rather than as a new job later. There is no minimum either way.
Related
Where to go next.
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The hub: every fixture family, quoted from your print.
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The flat, cut-profile version when no machined features are needed.
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