Clinched nail
A clinched nail is driven completely through the pieces being joined and bent over on the far side, so it holds by the bend rather than by friction. The Uniform Standard requires clinched pallet nails to fully penetrate the stack and be at least 1/4 in longer than its thickness.
Also called clinch nail, clinched fastener, mat nail
Reviewed
Where clinching is used
The main use is the block-pallet deck mat: top deckboards are nailed to the stringerboards with nails that pass through both boards and hit a steel plate on the assembly table, which turns the points over. PDS records this as "Mat Fasteners Clinched". A typical mat nail is a 1-5/8 in smooth nail.
Rules for clinched nails
- The nail must fully penetrate the stack
- It must be at least 1/4 in longer than the combined thickness of the pieces
- Clinched mat nails can be plain shank, because the bend provides the holding power
For example, a 3/4 in deckboard over a 7/8 in stringerboard is a 1-5/8 in stack, which calls for a nail of at least 1-7/8 in to clinch properly under that rule.
Why it matters
Thin boards give too little penetration for a straight nail to hold well by withdrawal. Clinching turns a short, cheap nail into a secure joint and keeps the mat together while it is nailed to the blocks. Soft mat nails score high MIBANT angles (over 100 degrees on one PDS sheet), which is what lets them bend. See pallet nails.
Questions
- How long should a clinched nail be?
- At least 1/4 in longer than the total thickness of the boards it joins, so there is enough shank to bend over.
Related
- Deck matA deck mat is the top deckboards and stringerboards of a block pallet pre-assembled as one unit, usually with clinched nails, before being nailed to the blocks.
- Plain-shank nailA plain-shank (smooth) nail has no threads and a withdrawal characteristic of 1.0, so pallets mainly use smooth nails as clinched deck-mat nails.
- Block classBlock class is the pallet class whose top deck sits on blocks, usually 9, joined by stringerboards. EPAL and 48x40 pooled pallets are block class.
- Pallet nails: types, sizes and how manyPallet nails are usually 2 to 3 in helical or annular threaded nails, 11 to 12-1/2 gauge. A GMA 48 x 40 uses 84 nails: 2 or 3 per joint by board width.
- Companion stringerA companion stringer is a repair part fastened alongside a cracked or broken stringer to restore it. The Uniform Standard lists it with plugs and C-blocks.
- CP palletCP pallets (CP1 to CP9) are nine standard block pallet designs for the chemical and plastics industry, from CP1 at 1000 x 1200 mm to CP9 at 1140 x 1140 mm.
Sources
- Uniform Standard for Wood Pallets (NWPCA, now Woodpack Global), 2012 edition
- Guide to Understanding the PDS Specification and Analysis (block class, metric)
- PalletOne: anatomy of the block pallet