Choosing between these two Mitutoyo items for dimensional metrology machine inspection comes down to what you actually need to do. The BHN506 is a replacement pressure switch assembly for a coordinate measuring machine, while the Surftest SJ-210 is a portable surface roughness tester. One restores a safety function in a CMM; the other measures surface finish. The price spread is wide: USD 399.00 versus USD 1,500.00, with the lower-priced part about 73% below the higher-priced tester.
Quick Verdict
If your CMM needs its air-pressure safety switch replaced, the Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T Coordinate Measuring Machine is the direct solution. If your work involves surface finish measurements and you can provide a power supply, the Mitutoyo Surftest SJ-210 Portable Surface Roughness Tester measuring instrument is the more useful tool. Both are in used condition, so keep that in mind before relying on either one.
Comparison
| Product | Price | Price indicator | Condition | Role | Best for |
|---|---|---|---|---|---|
| Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T Coordinate Measuring Machine | USD 399.00 | Used | CMM pressure switch assembly | Replacing the air-pressure safety switch in a CMM | |
| Mitutoyo Surftest SJ-210 Portable Surface Roughness Tester measuring instrument | USD 1,500.00 | Used | Portable surface roughness tester | Measuring surface finish at the machine or on the shop floor |
The BHN506 is a component; the SJ-210 is a measuring instrument. That distinction drives every practical difference.
Where Each Product Wins
- The BHN506 wins when you need a specific CMM pressure switch assembly. It is the only one of the two that fits that safety-sensor role, and it comes in at the lower end of the price spread.
- The Surftest SJ-210 wins when you need a portable measuring tool. It takes surface roughness readings, which the pressure switch cannot do, and it is priced at the higher end of the spread.
Product Notes
Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T Coordinate Measuring Machine
This assembly uses a Sanwa Denki SPS-8T adjustable pressure switch to monitor air pressure feeding a CMM's air bearings and pneumatic counterbalance. If pressure drops, the switch helps trigger a system interlock or fault signal. For a shop with a CMM waiting on this component, the part is the reason to buy: it addresses a specific safety point in the machine rather than requiring you to adapt a generic switch. The limitation is that it is not a complete measuring instrument. You need the surrounding CMM system and a way to confirm the assembly operates correctly in your air-pressure safety circuit. Because this is a replacement part for an existing machine, it belongs in a CMM repair workflow rather than on a bench as a standalone tool.
Mitutoyo Surftest SJ-210 Portable Surface Roughness Tester measuring instrument
The Surftest SJ-210 is a portable surface roughness tester from Mitutoyo, and it saw little use before the power supply went missing. Without that power supply, the unit could not be tested, so it is in an untested state. If your shop already has the correct power supply or can source one, this is a way to add portable surface finish measurement without buying new. The main limitation is the missing power supply: you cannot take a reading until you power the unit, and you will need to solve that before the tester becomes useful. If you need a ready-to-run instrument, this one requires an extra step before it can deliver any measurement.
Final Choice by Use Case
- For CMM air-pressure safety repair: Mitutoyo BHN506 Pressure Switch Sanwa Denki SPS-8T Coordinate Measuring Machine.
- For portable surface roughness measurement: Mitutoyo Surftest SJ-210 Portable Surface Roughness Tester measuring instrument.
If you need a replacement part to keep a CMM interlock functioning, the BHN506 is the clear match. If you need a portable instrument to measure surface finish and can manage the missing power supply, the Surftest SJ-210 is the one to consider.
