Welding Table editorial research · September 17, 2026 · Comparison method
A 5/8-inch dimension converts to 15.875 mm. It does not convert to 16 mm. The difference is small enough to disappear in rounded product copy and large enough that compatibility needs an explicit answer.
Strong Hand sells separate 16 mm and 5/8-inch Inserta clamp families. It also excludes FixturePoint tooling from several of its other systems. A shared brand name is therefore not a compatibility guarantee.
The diameter difference is only the first check
Subtracting 15.875 from 16 gives 0.125 mm. That calculation compares nominal labels, not the measured clearance between a specific pin and bore. Actual pin dimensions, bore tolerances, wear and the way a clamp locks still matter.
A smaller post entering a larger opening proves only that it can enter. It does not establish secure clamping, repeatable location or suitability for the force you intend to apply. Conversely, a nominally larger post should not be forced into a smaller system.
The grid mismatch can accumulate
Two inches is 50.8 mm, while a 50 mm grid is exactly 50 mm nominal spacing. Across four intervals the nominal center positions are 203.2 mm and 200 mm. A rigid multi-hole fixture built around one pattern cannot be assumed to align with the other.
A fixture using a single locating post avoids that particular multi-hole spacing issue, but its diameter and locking arrangement still require confirmation. A long adjustable slot may solve a positioning problem only within the accessory’s documented range.
Buy by the full part number
Strong Hand’s UDN6150 belongs to its 16 mm clamp range; UDN5150 belongs to its 5/8-inch range. Similar names and nearly identical product photographs make this an easy ordering mistake.
Keep the selected variant visible when reviewing an Amazon offer. A listing can group multiple sizes, and the title may describe the whole family. The selected size, included quantity and exact product image should agree before checkout.
When the manufacturer says no
The FixturePoint compatibility exclusion is more useful than a casual report that a tool “fits.” Respect an explicit exclusion even if the accessory appears to insert successfully. The manufacturer may be distinguishing engagement geometry or intended table construction as well as nominal size.
When neither manufacturer documents the pairing, treat it as unconfirmed. Ask for written confirmation naming both part numbers. Buying one sample to inspect can reveal an obvious mismatch, but a trial fit cannot replace approval for an unsupported combination.
Choosing a system before you own fixtures
Make a list of the tools your projects actually need: short hold-downs for flat stock, taller clamps for tubing, stops for repeated dimensions and brackets for upright parts. Price a usable set within each candidate system before selecting the table.
If you already own a substantial fixture collection, exact compatibility can outweigh a small difference in table price. Label storage by system and keep visually similar posts separated so a future helper does not have to identify them by eye.
Treat 16 mm and 5/8 inch as separate purchasing systems unless the exact pairing is explicitly supported.
Questions & answers
Can 5/8-inch clamps work in 16 mm holes?
Do not assume so from the conversion. Verify the exact clamp and table combination with the manufacturer; entering a hole is not the same as correct engagement.
Are 50 mm and 2-inch grids interchangeable?
No. Their nominal pitches differ by 0.8 mm per interval. Fixed multi-pin accessories are especially sensitive to that difference.