Spring Pin · Roll Pin Reference
Spring Pin & Roll Pin Size Chart
Measure the hole the pin installs into, then read across. The recommended hole size columns (highlighted) are your drill/ream target — the pin compresses on its slot to grip the bore.
Slotted spring pin
| Pin diameter · nominal (in) | Recommended hole / drill | Spring-pin dimensions | Wall | Insertion tool | |||||
|---|---|---|---|---|---|---|---|---|---|
| Decimal | Fraction | Min | Max | A · Go ring | D* · Avg Ø | B · Max Ø | C · Slot gap | Wall | B&M Pintool |
| Insertion tool | Pin diameter · nominal | Recommended hole / drill | Guide bore | ||||||
| B&M Pintool | Nominal Ø (mm) | Decimal Ø (in) | Recommended hole, H12 (mm) | øG (in) · min / max | |||||
| .062 | 1/16 | .062 | .065 | .069 | .066 | .059 | .011 | .012 | PT-062 |
| .078 | 5/64 | .078 | .081 | .086 | .083 | .075 | .014 | .018 | PT-078 |
| .094 | 3/32 | .094 | .097 | .103 | .099 | .091 | .018 | .022 | PT-094 |
| .125 | 1/8 | .125 | .129 | .135 | .131 | .122 | .024 | .028 | PT-125Flagship |
| .156 | 5/32 | .156 | .160 | .167 | .162 | .151 | .028 | .032 | PT-156 |
| .187 | 3/16 | .187 | .192 | .199 | .194 | .182 | .036 | .040 | PT-187 |
| .219 | 7/32 | .219 | .224 | .232 | .226 | .214 | .042 | .048 | — |
| .250 | 1/4 | .250 | .256 | .264 | .258 | .245 | .042 | .050 | PT-250 |
| .312 | 5/16 | .312 | .318 | .328 | .321 | .306 | .060 | .062 | — |
| .375 | 3/8 | .375 | .382 | .392 | .385 | .368 | .060 | .077 | — |
| .437 | 7/16 | .437 | .445 | .456 | .448 | .430 | .060 | .077 | — |
| .500 | 1/2 | .500 | .510 | .521 | .513 | .485 | .060 | .094 | — |
| PT-2MM | 2 mm | .0787 | 2.00–2.10 | .097 / .101 | |||||
| PT-3MM | 3 mm | .1181 | 3.00–3.10 | .140 / .145 | |||||
| PT-4MM | 4 mm | .1575 | 4.00–4.12 | .183 / .187 | |||||
| PT-5MM | 5 mm | .1969 | 5.00–5.12 | .222 / .226 | |||||
| PT-6MM | 6 mm | .2362 | 6.00–6.12 | .266 / .270 | |||||
All dimensions in inches · D* = average diameter · chamfer features optional
Installing or removing a pin? See:
- How to Install a Roll Pin Without Marring the Finish
- How to Remove a Roll Pin Without Damaging the Part
Chart Notes: Nominal pin diameter, recommended drill hole size, go-ring gage, average diameter, slot gap and wall thickness — 12 slotted spring-pin sizes from 1/16″ to 1/2″ (inch, ASME B18.8.2). Metric Pintool sizes (2–6 mm) cover standard ISO 8752 / DIN 1481 spring (roll) pins — recommended holes per ISO 286 H12, with guide-bore (øG) references. Spring pin and roll pin are the same part; this chart covers both.
Size to the hole, not the loose pin
A free spring pin measures slightly oversize and compresses on its slot as it enters the bore. Drill/ream to the recommended hole range and the pin self-retains — no adhesive, no staking.
Spring pin = roll pin = slotted pin
All three name the same hollow, slotted spring-steel pin. "Spring pin" and "slotted pin" are the engineering terms; "roll pin" is the common shop name. This chart serves all of them.
Reading the chart
- Inch view in inches; metric view in millimeters, with decimal-inch equivalents
- D* represents the average diameter
- Chamfer features are optional
Stop fighting your roll pins
The B&M Pintool holds the pin square to the bore and presses it straight — no dropped pins, no peened ends, repeatable across a production run.
Working with spring pins
Hole prep, install & reference
The dimensions above do the specifying. Here's how to put them to work.
Drill, ream, deburr
Drill to the recommended hole min, ream toward max for a controlled press fit, and deburr the lead-in. Through-holes want a slight chamfer so the pin starts without shaving.
Press square, every time
Start the pin by hand, then drive it with the matching B&M Pintool — by hand, hammer, or arbor press. The guide keeps it from walking or mushrooming over.
Specs these follow
Slotted spring pins are commonly specified to ASME B18.8.2 (inch) and ISO 8752 (metric). Use those alongside this chart when calling out a pin on a drawing.