When a Mitutoyo BHN506 coordinate measuring machine is on the fritz, the diagnosis is rarely 'replace the whole CMM.' More often, one component has aged out of spec: the calibration ball, the pressure switch, the axis drive motor, or the scale-reading head. These four used replacement parts are built for the BHN506, but they solve very different problems. Choosing the wrong one means downtime continues, and choosing the right one depends on matching the part to the symptom. For anyone maintaining a BHN506 in a dimensional metrology machine inspection program, the decision starts with identifying which subsystem is failing.
Quick take
- Mitutoyo 06AAC557 Master Ball for calibration and probe qualification.
- Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T for air-supply fault signals.
- Yaskawa Minertia UGTMEM-06MMT51 for drive response and positioning.
- Mitutoyo 908926 SRD Head 10/10 for linear scale feedback.
All four are used components with Japanese origin, so the choice comes down to function.
Listed price comparison
| Replacement part | Listed price | Price bar | Role |
|---|---|---|---|
| Mitutoyo 06AAC557 Master Ball | USD 1,299.00 | Probe calibration reference | |
| Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T | USD 399.00 | Safety interlock | |
| Yaskawa Minertia UGTMEM-06MMT51 | USD 1,998.00 | Axis drive servo motor | |
| Mitutoyo 908926 SRD Head 10/10 | USD 399.00 | Linear scale reading head |
Decision matrix
| Symptom or task | Recommended part | Why it fits |
|---|---|---|
| Probe tip qualification | Mitutoyo 06AAC557 Master Ball | Reference for probing system alignment and error compensation |
| Low-pressure fault | Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T | Monitors pressure to air bearings and triggers fault signal when pressure drops |
| Axis movement accuracy | Yaskawa Minertia UGTMEM-06MMT51 | High-torque, low-inertia DC servo motor for smooth travel |
| Scale feedback | Mitutoyo 908926 SRD Head 10/10 | Reads linear scale graduations and converts movement to signals |
Product notes
#### Mitutoyo 06AAC557 Master Ball for Mitutoyo BHN506 Coordinate Measuring Machine
If the CMM is reporting probe misalignment or inconsistent tip measurements, the 06AAC557 Master Ball is the component to look at. The master qualification ball serves as a reference for probing system alignment, tip qualification, and error compensation, making it a calibration fixture rather than a motor or sensor part. The BHN506 model number confirms it is a direct system match. The trade-off is functional scope: this ball does not monitor pressure, drive the axes, or read the scale. Its role starts and ends at giving the probe a known surface to measure. That makes it the part to pick when the goal is restoring confidence in measurement data, not fixing a mechanical failure.
#### Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T Coordinate Measuring Machine
When the BHN506 alarms on air supply, the Sanwa Denki SPS-8T pressure switch is the component made for that fault. It monitors the air pressure feeding the air bearings and pneumatic counterbalance, then triggers a system interlock or fault signal when pressure drops below the operational threshold. That makes it a protective part: it prevents damage to guideways and axis mechanics. The limitation is the narrow scope. It cannot calibrate a probe, move an axis, or translate scale readings, so it is only the right choice when the symptom points to pressure loss. Its model number ties it directly to the BHN506.
#### Yaskawa Minertia UGTMEM-06MMT51 for Mitutoyo BHN506 Coordinate Measuring Machine
For a CMM that hesitates, vibrates, or drifts while moving an axis, the Yaskawa Minertia UGTMEM-06MMT51 is a high-torque, low-inertia DC servo motor built for the BHN506. It is intended to provide rapid dynamic response and precise positioning, which supports smooth travel along the guideways during inspection routines. The motor is the most expensive component in this comparison, so it is best reserved for problems that point clearly to the drive axis. It will not address probe calibration, pressure interlocks, or scale-reading feedback. If the axis drive is the weak link, this is the part that matches the mechanical need. The Yaskawa Minertia motor is tied specifically to the BHN506 system.
#### Mitutoyo 908926 SRD Head 10/10 For Mitutoyo BHN506 Coordinate Measuring CNC
If the BHN506 controller is losing position feedback, the SRD Head 10/10 is the part that reads linear scale graduations and converts axis movement into high-resolution electrical signals. In a CNC coordinate measuring machine, that feedback loop is what keeps positioning repeatable. The head is a scale-reading component, so it is the right pick when the problem is in the data path rather than the pressure or drive systems. Its limitation is equally specific: it will not help with calibration, pressure faults, or motor travel. The model 908926 gives a clear reference to the BHN506 and its CNC operation.
Final recommendation
Match the part to the subsystem: choose the 06AAC557 Master Ball when you need a calibration reference for the probe, the SPS-8T pressure switch when pressure faults trigger alarms, the Yaskawa Minertia motor when axis drive performance is the problem, and the SRD Head 10/10 when scale feedback is unreliable. If you are working through a dimensional metrology machine inspection, the two fault-path parts cover pressure and scale-reading failure modes. If measurement confidence is the issue, the Master Ball directly supports accuracy.
