BDS A024 vs B024 Compact Datum: How to Choose a Positioning Datum for Robot-Handled Fixture Carriers

Should the robot pallet use the smaller BDS A024, or step up to B024? Both bodies list the same hold-down force. Compare table space and complete robot payload first, then verify actual support-contact spacing and the selected model’s approved load and moment limits.

A compact positioning datum is the small receiver on the machine table. The robot carries a matching pallet, often called a fixture carrier. The pallet drops onto the receiver. The receiver holds it while the mill cuts. Shop air then opens the lock so the robot can lift the pallet out.

NEXTAS sells this stack as the BDS family. The two common bodies are A024 and B024. The selected model drawing still wins over this page.

What sits on the table?

Keep two parts distinct. The datum body stays on the machine, the trunnion, or a setup bench. The datum pallet is the part the robot moves. Vises, nests, or dovetail blocks bolt to that pallet. If you order the wrong pair, the robot cannot seat the job.

BDS is the compact family for that handoff. It is smaller than a large multi-receiver zero-point plate. Use BDS when the table, the 5-axis platter, or the gripper needs a short stack. Use a larger plate family when the fixture is wide and the cut is heavy. The BDS product page is the current product-page source for the retained numbers in this article.

The retained product information describes the same spring-and-ball lock for A024 and B024. Hardened balls, pushed by springs, pull the pallet down. Shop air at 0.5 to 0.8 MPa compresses those springs to unlock. When air vents, the springs hold again. That shared lock does not make an A024 pallet interchangeable with a B024 body. The hold is a process hold. It is not a safety-rated stop unless the full cell safety design says so.

The retained product information also describes a centre lift inside the receiver. Confirm the actual unlock, lift, cleaning and seat-check mechanisms for the selected body and pallet pair. Air extends that lift so the pallet first lands on a cushion, not on the precision locating faces. Seals and an air blast help keep chips out of the seat. An air-seat check can then watch the seat: it is a process check that can block Cycle Start when the pallet is not down, not a safety stop. Set the leak or pressure limit on the real cell.

Same listed force, two different bases

A common first question is: if A024 and B024 both list 60,000 N and seat closer than 0.003 mm, why pay for the larger body?

The listed force is the spring pull-down on the selected body, not the side load or overturning moment a tall fixture can accept. The effective support contacts, their spacing and the load path determine resistance to tipping. External body width does not establish that contact geometry. Review the approved support, moment and load limits for the actual body, pallet and fixture.

A024’s body is 320 × 240 × 50 mm. B024’s body is 330 × 267 × 50 mm. The short side grows from 240 mm to 267 mm, an external-footprint difference of 27 mm. These dimensions help check table fit. They do not show the effective seating area, support-contact spacing or an increase in approved tipping resistance.

The retained product information gives the same reseat closeness: below 0.003 mm on both main bodies. That figure is how close the pallet sits again on the selected interface. It is not a finished-part tolerance, and it is not a coordinate measuring machine (CMM) transfer result. Prove those on the project.

Retained sizes and weights

Values below are retained from the current BDS product page and have not been independently catalogue-verified. Confirm the latest selected body and matching pallet drawings and your order confirmation before freezing dimensions, weights, robot payload or operating limits.

Keep the body and pallet in the same family. An A024 pallet is not a drop-in on a B024 body. Confirm the pair on the interface drawing before the robot program is written.

Both bodies use four Ø13 mm mounting slots. Torque the screws on a clean, flat plate. Confirm flatness on the approved drawing. Do not twist a hardened body onto a bowed subplate and then blame the seat.

Can a side cut tip the pallet?

A024 has the smaller listed footprint and may enter a shortlist for a compact 5-axis platter or enclosure after drawing review. B024 adds 27 mm on the external short side. For a tall fixture or heavy side cut, compare the actual support-contact geometry and approved moment/load limits. Do not use the 320 × 240 mm body outline as the effective seat size or infer that B024 resists more tipping from its footprint alone.

This is planning talk, not a NEXTAS load test. Send part height, tool path, and fixture mass if the cut is aggressive. Do not treat 60,000 N as a licence to cantilever a tall tombstone on the small body.

Will the robot still lift it?

Every kilogram on the pallet is a kilogram the robot cannot spend on the part. The A024 pallet lists 7.5 kg. The B024 pallet lists 10 kg. That is 2.5 kg of extra empty-pallet weight on every transfer.

On a compact six-axis arm in the 12 kg to 20 kg class, 2.5 kg can be the difference between keeping the current robot and buying a heavier one. Count the pallet, the gripper fingers, the vise, and the part. Write “unknown” on any line you have not weighed.

If the robot payload is tight and the fixture is tall or the cutter pushes sideways, do not freeze A024 from payload alone. Send height, tool path, fixture mass, and the arm chart at the real centre of gravity. The actual support geometry and approved moment/load review may favor B024, A024 or a larger plate; body width alone cannot decide.

An arm in the 25 kg class or above and a table that accepts 330 × 267 mm may make B024 feasible for the shortlist. They do not prove a wider effective seat or better tipping resistance. Confirm actual support contacts, allowed moment/load and the complete pallet payload before selecting either body. Those robot classes are planning ranges, not a NEXTAS robot spec. Use the arm maker’s payload chart at your real centre of gravity. A pallet that is legal at rest can still over-torque the wrist in a fast flip.

Planning example: robot pallet placement

The following sequence and approximate approach window are planning examples, not an approved cell program. Confirm the selected body and pallet drawings, actual unlock and lift mechanisms, support and gripper handoff, interlocks and the complete cell qualification with the integrator before programming. Rushing the last 20 mm can scar the precision locating faces.

1. Planning example: bring the pallet to about ±0.5 mm of the seat. Confirm the allowed approach window for the actual mechanism; this is not a precision claim.
2. Turn on unlock air at 0.5 to 0.8 MPa. The lock balls retract. The centre lift rises.
3. Lower the pallet onto that lift, not onto the precision locating tapers.
4. Let the air blast clear chips from the seat.
5. Release the gripper. Vent the air. The springs pull the pallet down.
6. Confirm the monitored seating state, mechanical lock, robot clearance and all released machine/cell-ready conditions before permitting Cycle Start.

If unlock pressure is low, the balls may not clear. The robot then drags the pallet. Wet or oily air can impair operation. Follow the selected model’s released air-quality, inspection and service requirements; do not infer a universal service interval. Confirm pressure at the receiver, not only at the compressor.

The air-seat check should block Cycle Start when the pallet is not down. It is not proof of a safety-rated function. Four 90° landing rotations let the robot set the pallet down in four square angles. That helps when the enclosure is not square to the load aisle. Confirm the home angle on the drawing. Do not assume every station uses the same one.

One datum from the bench to inspection (CMM)

Reclamping between roughing, wash and inspection can add variation. Keeping the part on the same identified pallet may avoid that reclamp, but matching BDS interfaces on the setup bench, mill and coordinate measuring machine (CMM) do not by themselves preserve one coordinate origin. Each station adds mounting, alignment, reference and measurement effects.

Use approved matching body/pallet pairs at every station, then define station alignment and a controlled transfer measurement. Record reference points, raw and corrected results separately, measurement uncertainty and acceptance limits. Release only the tested transfer chain. A BDS pallet combined with another receiver adds an interface that also needs review; a family label alone proves neither fit nor datum transfer.

If the fixture is already a full-size zero-point plate, do not force BDS into that job. Size the receivers from the 85 / 120 / 160 / 195 mm receiver guide. BDS is the compact fork, not a substitute for a four-receiver plate on a wide tombstone.

Which model should you shortlist?

Lean toward A024 when:

• The table or 5-axis platter cannot take a 330 × 267 mm body.
• The robot payload is tight, and 7.5 kg of pallet mass matters.
• The cut is light to medium: aluminium, drilling, or finish work.
• You want more than one compact datum on one subplate.

Lean toward B024 when:

• The fixture or part extends beyond A024’s 320 × 240 mm external outline and the actual support/load review calls for a different layout.
• The table can take the 330 × 267 mm body.
• The robot can carry a 10 kg pallet plus the vise and the part.
• The approved support-contact geometry and moment/load limits meet the job; the 27 mm footprint increase alone is not evidence of that fit.

Shortlist conditions are not acceptance limits. Confirm actual support contacts, mounting, load and moment for either body. If neither fits the table or meets those approved limits, stop. You may need a larger zero-point plate, not a bigger BDS. Say that in the quote pack. Do not stretch a compact datum across a job it cannot support.

What to put in the BDS quote pack

NEXTAS can review the BDS body, the matching pallet, and open questions on the stack. We cannot sign off a robot brand, a cell safety plan, or a coordinate measuring machine (CMM) program from this page. Send this brief so the quote talks about the same machine.

• Table: machine model, platter or tombstone size, leftover tool length, and a photo of the current plate. Write “unknown” if a field is open.
• Robot: maker and model, listed payload, and the true centre of gravity with gripper plus pallet.
• Job: part size, material, fixture height, and whether the cutter takes a heavy side cut.
• Flow: setup bench, mill, wash, and inspection (CMM). Note which stations need a matching receiver.
• Air: pressure you can hold at the receiver, not only at the compressor.

Ask for the body and pallet pair, the index home, and the open questions. The cell builder still owns reach, guarding, and recovery. The process owner still has to prove chips, probes, and first-part checks on the mix.