Grip number against stack thickness
Where to buyStack = total thickness of the sheets at the hole, measured. Both systems number the grip in sixteenths of an inch as the maximum grip; each number covers one sixteenth below it. CherryMAX writes two digits (CR3213-4-04), Hi-Lok one or two (HL18PB8-8).
| Grip no. (CherryMAX / Hi-Lok) | Max grip | Stack covered, in | Stack covered, mm |
|---|---|---|---|
| -01 | 1/16 in | .025 to .062 | 0.6 to 1.6 |
| -02 / -2 | 1/8 in | .063 to .125 | 1.6 to 3.2 |
| -03 / -3 | 3/16 in | .126 to .187 | 3.2 to 4.7 |
| -04 / -4 | 1/4 in | .188 to .250 | 4.8 to 6.3 |
| -05 / -5 | 5/16 in | .251 to .312 | 6.4 to 7.9 |
| -06 / -6 | 3/8 in | .313 to .375 | 8.0 to 9.5 |
| -07 / -7 | 7/16 in | .376 to .437 | 9.6 to 11.1 |
| -08 / -8 | 1/2 in | .438 to .500 | 11.1 to 12.7 |
| -09 / -9 | 9/16 in | .501 to .562 | 12.7 to 14.3 |
| -10 | 5/8 in | .563 to .625 | 14.3 to 15.9 |
| -11 | 11/16 in | .626 to .687 | 15.9 to 17.4 |
| -12 | 3/4 in | .688 to .750 | 17.5 to 19.0 |
CherryMAX ranges as printed in Cherry CA-1015 (CherryMAX Process Manual), p. 4. Hi-Lok ranges are derived: the drawing says the second dash is the maximum grip in 1/16 in, with a grip tolerance of ±.005 in; the range is not printed there. mm converted from inches (25.4).
CherryMAX minimum grip, number -01
| Diameter | Universal head, min (in) | mm |
|---|---|---|
| 1/8 (-4) | .025 | 0.64 |
| 5/32 (-5) | .031 | 0.79 |
| 3/16 (-6) | .037 | 0.94 |
CA-1015 p. 4, "-01 minimum grip guidelines". The flush-head and Unisink columns of that table are read in the manual, not repeated here. For double-dimpled sheets add the countersink head height to the thickness (same page).
Hi-Lok pin protrusion above the collar
After the collar shears off, the pin must stand inside this window. Too short: use the next longer grip. Too long: the next shorter, if the drawing allows it.
| Diameter dash | Min (in) | Max (in) | Min–max (mm) |
|---|---|---|---|
| -5 (5/32) | .302 | .384 | 7.7–9.8 |
| -6 (3/16) | .315 | .397 | 8.0–10.1 |
| -8 (1/4) | .385 | .467 | 9.8–11.9 |
| -10 (5/16) | .490 | .572 | 12.4–14.5 |
| -12 (3/8) | .535 | .617 | 13.6–15.7 |
NASA PRC-9007C (Sept 2020), section 6.3, Table 1, "Hi-Lok Pin Protrusion"; the Omega Technologies catalogue p. 12 repeats -5 to -12. Larger dashes are in the NASA table.
How to pick the number
CherryMAX. Measure the structure at the hole with the 269C3 grip gauge (CA-1015 p. 11), reading at the visible surface; if the structure is dimpled or countersunk, measure to the surface of the structure, not to the dimple. Take the number equal to the next higher gauge reading; if the reading is exactly on a line, either that number or the next higher one.
Hi-Lok. Grip dash n = the stack in sixteenths rounded up (derived from the drawing's "second dash = maximum grip in 1/16"; the Omega grip scale p. 13 shows a 6/16 in stack taking -6). One step longer or shorter is allowed only if the engineering drawing permits it (NASA PRC-9007C 6.2.3). Check the protrusion table after installation.
Ordering. Stocked part numbers skip some dashes: the 3/16 CherryMAX listing in our data sheet has no -10, and the shortest Hi-Lok dash depends on diameter. Check the data sheet of the exact series before ordering.
Worked example
Two sheets, 0.063 + 0.090 in, measure 0.152 in (3.86 mm) at the hole.
- 0.152 × 16 = 2.43, rounded up: 3.
- CherryMAX: -03 covers .126 to .187 in. Hi-Lok: -3 covers .0625 to .1875 in (derived).
- Part numbers: CR3213-4-03 for a 1/8 universal CherryMAX; HL18PB6-3 for a 3/16 Hi-Lok shear pin.
Grip number 3 in both systems; check the drawing for the series.
Questions people actually ask
Is a Hi-Lok grip the same as a CherryMAX grip?
The numbering idea is the same (maximum grip in sixteenths), so the band for a given number is the same. The parts are not interchangeable, and the gauges are not.
What if my stack falls exactly on a boundary?
For CherryMAX the gauge rule allows either number when the reading is on a line. For Hi-Lok use the longer pin and check protrusion, unless the drawing says otherwise.
Where is the hole size?
Not here. Hi-Lok holes are prepared to NAS618, which is not public, and CherryMAX holes follow Cherry's tables. Take them from the SRM, drawing or maker data.
Limits — when NOT to use this chart
What the sources support, and no further.
- Hi-Lok ranges are derived, not printed by the maker. Confirm with the drawing.
- Other blind fasteners (Cherrylock, Olympic, Visu-Lok) number their grips their own way.
- Stock lists differ from the standard. The standard or maker may list dashes that a listing omits.
- The SRM, drawing and IPC govern the choice of fastener and whether a one-step substitution is allowed.
Where to buy
Distributors coming soon.
Sources
- Cherry CA-1015, CherryMAX Process Manual (SPS Fastener Division), pp. 4 and 11 — numbering system, grip table -01 to -12, -01 minimum grip, 269C3 grip gauge and its use.
- Hi-Shear / LISI drawing HL18 rev. 28 (2016-02-25) — second dash as maximum grip in 1/16 in, grip tolerance ±.005 in.
- NASA PRC-9007C (Sept 2020), section 6.2.3 and 6.3 Table 1 — one-step grip substitution; Hi-Lok pin protrusion.
- FAA AC 43.13-1B CHG 1, Chapter 4, par. 4-57 — CherryMAX diameters, heads, and lengths in 1/16 in increments.