When you're setting up dimensional metrology machine inspection, the first decision splits into two different purchases: tension clamps that hold a workpiece on a CMM fixture, and an optical light source that supports non-contact inspection on a specific machine. The three clamp sets here differ by thread and reach, while the Mitutoyo Scope CF20 serves a completely separate role on a Mitutoyo BHN506 CMM. The practical starting point is to match the thread type and clamp reach of the fixture system you already use.
Listed price comparison
The table below puts the four options side by side. The price bars are scaled to the spread from the lowest to the highest listed price.
| Product | Listed price | Price bar |
|---|---|---|
| CMM Fixtures Tension Clamp R-CT-160-275-20 KMG | USD 20.21 | |
| M6 Spring Fixed Board Fixed Pole L55mm | USD 20.00 | |
| DANTECH CMM Tension Clamp M6 L87mm | USD 26.00 | |
| Mitutoyo Scope CF20 Optical Light Source | USD 2,698.00 |
Decision matrix
| Your setup | Product to look at | Why it fits |
|---|---|---|
| Compact clamp for M6 threads | M6 Spring Fixed Board Fixed Pole L55mm | 55 mm clamp in a set with one tension clamp and one post |
| 1/4-20 threaded fixture | CMM Fixtures Tension Clamp R-CT-160-275-20 KMG | 1/4-20 thread with 55 mm clamp and 78 mm post |
| Longer clamp reach with M6 | DANTECH CMM Tension Clamp M6 L87mm | 87 mm clamp with M6 thread |
| Optical light for Mitutoyo BHN506 | Mitutoyo Scope CF20 Optical Light Source | CF20 light source designed for non-contact optical inspection |
Product notes
CMM Fixtures Tension Clamp R-CT-160-275-20 KMG
This SUXING set is the match when your fixture uses a 1/4-20 threaded post. It is a new set that includes one tension clamp and one post, with a 55 mm clamp and a 78 mm post. In practical terms, that gives you a compact hold-down method for keeping a workpiece steady during inspection. The clamp length is short enough to fit many small fixture plates, and the 78 mm post gives the clamp something to grip. The limitation is the thread standard: 1/4-20 will not thread into an M6 hole, so the set is only useful for fixtures and tooling plates built around 1/4-20 hardware. If your workholding is already metric, this set is not the one to start with.
M6 Spring Fixed Board Fixed Pole L55mm
For M6-based fixture builds, this compact set is the starting point. It includes one tension clamp and one post, and the 55 mm clamp length keeps the setup small. The fixed board and fixed pole design gives you a simple way to identify the M6 option, and the M6 thread is a common standard for CMM tooling plates. The package is a single set, so you know exactly what arrives: one clamp and one post rather than a bulk lot. The limitation is reach: if your part sits farther from the mounting surface, this 55 mm clamp is the shorter choice and you would want the 87 mm M6 version instead. For close-in inspection work, the compact footprint is the main draw.
CMM Tension Clamp/Inspection Tooling M6 Spring Fixed Board Fixed Pole L87mm
DANTECH makes this M6 tension clamp set, which trades a more compact footprint for 87 mm of clamp length. The set retains a 78 mm post, so the extra reach comes from the longer clamp rather than a taller post. That makes it the better fit when the workpiece is positioned farther from the fixture plate, or when you need to clear a raised feature on the part. The M6 thread also matches the same standard as the L55mm set, so it can work alongside it on the same tooling plate. The limitation is the opposite side of the same tradeoff: the longer clamp is more than you need in a tight fixture where a 55 mm clamp would clear the area more easily.
Mitutoyo Scope CF20 Optical Light Source
This is not a tension clamp; it is a specialized illumination unit for a Mitutoyo BHN506 CMM. It is a used unit made in Japan, and its intended role is to supply bright, uniform light for non-contact optical inspection and edge-detection work through the CF20 scope assembly. The CF20 light source is a machine-specific part for a CMM that already uses the CF20 microscope setup. The limitation is compatibility: the light source is for the BHN506/CF20 setup, not a generic replacement that can be adapted to just any CMM.
Final recommendation
Let the fixture thread and reach decide among the three clamp sets: the SUXING clamp handles the imperial-thread fixture case, and the two metric pole sets split by clamp length. The optical light source sits at the high end of the price spread, which runs from USD 20.00 to USD 2,698.00. That spread shows that the mechanical clamps and the optical light source are solving very different problems in a dimensional metrology machine inspection workflow.
