What are Tri-Fold Rivets?
Tri-fold rivets are blind rivets that split into three legs on the blind side when set. The legs spread load over a wide area, which helps prevent cracking and pull-through in soft or brittle materials.
What are tri-fold rivets used for on plastic and fiberglass?
- Panels and fairings made from plastics, fiberglass, and composites
- Thin sheet where a standard rivet head might pull through
- Repairs and field installs where thickness varies
Tri-fold vs bulb-tite, which should I choose for higher strength?
- Tri-fold: Excellent load distribution in soft materials, non-structural strength profile
- Bulb-tite structural: Higher shear and tensile for demanding joints, choose when a specification calls for structural blind rivets
Do tri-fold rivets need a sealing washer for waterproof installs?
Use a sealing-washer version when splash resistance is required. For demanding exposure, pair correct hole sizing and deburring with a compatible sealant.
What drill size and hole prep do tri-fold rivets require?
Use a snug, clean hole and deburr both sides. Common pairings are listed below, verify the exact drill for your series.
| Nominal rivet diameter | Recommended hole size (in) | Common drill size |
|---|---|---|
| 3/32 in | 0.097 to 0.100 | #41 |
| 1/8 in | 0.129 to 0.133 | #30 |
| 5/32 in | 0.160 to 0.164 | #20 |
| 3/16 in | 0.192 to 0.196 | #11 |
| 1/4 in | 0.257 to 0.261 | Letter F |
Notes: Drill square to the surface, deburr both sides, keep the hole just over the body diameter for consistent setting.
Will tri-fold rivets work in oversized or irregular holes?
The three legs provide wider bearing on the blind side, which can help in slightly irregular holes. If the hole is significantly oversized, move up in diameter or use a backing washer.
How to choose grip range, head style, and material
- Grip range: Match to the total stack thickness, if near the limit, select the next range
- Head style: Dome for most panels, large flange to add bearing on thin or soft materials, countersunk for a flush surface
- Material: Aluminum body with aluminum or steel mandrel for most builds, stainless for added corrosion resistance
- Low-profile options: Shave-head and recessed-crown styles reduce the visible profile after installation
Installation and best practices
- Measure total stack thickness, choose a rivet whose grip range covers it
- Drill to the size above and deburr both sides
- Insert from the finished side, support the joint, keep the tool square so the legs form evenly
- Pull the mandrel until it snaps
- For sealing at the head, use a sealing-washer version and seat fully
Common issues and quick fixes
- Legs tear through soft material, move up in diameter, add a backing washer, or use large flange on the visible side
- Rivet spins in the hole, hole is oversized, step up diameter or confirm correct drill size
- Uneven leg formation, tool not square or hole not deburred, correct technique and re-set
Why buy Tri-Fold Rivets from AlbanyCountyFasteners.com
- Wide range of diameters, grip ranges, and head styles
- Sealing-washer, shave-head, and recessed-crown options
- Fast shipping with contractor-friendly quantities and bulk pricing
- USA-based support for drill sizes, grip selection, and installation tips
FAQs
Answers to high-intent questions about selecting, drilling, and using tri-fold rivets.
Are tri-fold rivets structural?
No, they are non-structural. For higher shear or tensile needs, choose structural blind rivets such as bulb-tite styles in a different category.
Do I need a sealing washer for outdoor use?
Use a sealing-washer version for splash exposure, for full waterproofing, combine correct hole sizing with a compatible sealant as needed.
What drill size should I use for 1/8 in and 3/16 in?
Use #30 for many 1/8 in series and #11 for many 3/16 in series, see the table above and verify for your exact part number.
Can tri-fold rivets be shaved for a lower profile?
Yes, shave-head and recessed-crown versions allow a lower finished profile at the head after installation.
Do tri-fold rivets work in slightly oversized holes?
The three legs help with irregular holes, if the hole is too large, move up in diameter or add a backing washer.