A 25mm Throw and a Collar That Spins: Deadbolts D101 and D102

A deadbolt is the second lock on a door, and it exists because the first one cannot do this job. A latch is sprung, so it can be pushed back; a deadbolt is thrown by a key or a turn and has no spring behind it, which means the only way past it is through the bolt, the door or the frame. Everything worth specifying about one follows from that sentence.

The throw is the first number and ours is 25mm (1") on both the D101 and the D102. Twenty-five millimeters is the figure most specifications mean when they ask for a full-throw or one-inch deadbolt, and the reason it is a specification at all is the frame: a bolt that engages less than about 20mm (13/16") can be forced by spreading the jamb, which is a two-minute attack with a car jack that does not look like forced entry afterwards.

The bolt itself is published as zinc die-cast with a hardened steel roller pin. The roller pin is the anti-saw feature and it works mechanically rather than by hardness alone: a hacksaw blade drawn across it makes the pin rotate, so the teeth skate instead of cutting. It is a detail that costs almost nothing to include and is left out of cheap deadbolts, and it is invisible in a product photograph, which is why it belongs in a comparison rather than in a showroom.

The cylinder on the D101 is published as a five-pin tumbler with a solid brass plug and two nickel-plated keys. Five pins is the residential standard; the plug being solid brass rather than a zinc casting is what lets it be re-pinned cleanly, which matters on any building where keys will be changed between tenants. If your project needs more than five pins or a restricted keyway, that is a different conversation and worth having before the order.

The feature that decides more attacks than any of the above is the free-turning cylinder trim. The collar around the cylinder spins freely, so a wrench or a pipe put on the outside of the lock turns the collar and not the mechanism. Without it, the commonest forced entry on a deadbolt is simply twisting the whole cylinder out of the door, which takes about as long as it takes to describe. Both the D101 and the D102 publish it.

Both are fully reversible, left or right hand, and both publish an internal chassis of zinc-plated steel with exposed trim available in stainless steel, brass or steel. Finishes differ between the two: the D101 is published in antique brass (US5) and antique copper (US11) among others, the D102 in antique copper and polished brass (US3). Those US numbers are the older convention; antique finishes are relieved rather than uniform, so they are not translatable to a single BHMA number, for the reason set out in our finish-code article.

The row that turns these from a component into a specification is keying: both are published as keyable to pair with an entrance bored lock. That is what a building actually wants, one key for the lever set and the deadbolt on the same door, rather than a tenant carrying two. It also means the deadbolt has to be ordered in the same keying group as the lock above it, which is a decision taken at order stage and not afterwards.

If the door you are working on cannot take a bored deadbolt at all (because it is glazed, because the stile is too narrow, or because it is an existing door nobody wants to drill twice) the rim night latch is the alternative, and we have written that range up separately. A 564 or a 1073 mounts on the face and needs one hole, and the rim deadbolt versions of those throw the same 25mm. It is a different fixing, not a lesser lock.

The door preparation, and why it matches the lock above

Two rows decide whether a deadbolt fits the door at all, and on the D101 and D102 they are the same two rows as on our cylindrical locks: a backset adjustable between 60mm (2-3/8") and 70mm (2-3/4"), and a door thickness of 35mm (1-3/8") to 45mm (1-3/4"). That match is deliberate rather than convenient. A door bored for one of our entrance locks at 60mm takes the deadbolt at 60mm too, the two sit in a vertical line, and one key can work both, which is the arrangement the keying row exists to support.

Outside that door range, say so before the order. A leaf thicker than 45mm needs a longer cylinder and tail piece, and a leaf thinner than 35mm leaves the trim unable to clamp properly. Both are solvable; neither is solvable on site with the parts in the box.

Single or double cylinder: a decision about the building

The D101 DSPB is published as single cylinder, for entrance doors: a key outside, a thumbturn inside. A double-cylinder deadbolt needs a key on both faces, and the argument for it is always the same: glass within reach of the lock, where someone could break a pane, reach through and turn the thumbturn.

The argument against it is also always the same, and it is stronger: in a fire, the key has to be found before anyone gets out. Many jurisdictions restrict or prohibit double-cylinder deadbolts on doors used for escape, for exactly that reason, and the rule that applies to your door is the local one, not ours. If the glass is the problem, the better fixes are usually to change the glass or move the lock, not to put a key between the occupants and the street. We will supply what the building allows; the decision belongs to whoever answers for the building.

A 25mm throw only works if the frame holds

A full-throw deadbolt is a strong bolt going into a weak place. The bolt passes into the strike on the frame, and the strike is screwed to the frame lining; on many doors that lining is a thin strip of softwood nailed to the structure behind it. Kick the door and the bolt does not break, the lining splits and the strike comes away with it.

So the most effective security upgrade on a deadbolt costs almost nothing: screws long enough to pass through the lining into the structural frame behind it, at the strike and at the hinges on the opposite edge. That is general practice rather than a feature of our product, and it is worth putting in the installation note on any schedule, because the installer who fits the lock is rarely the person who will be asked why it failed.

Rekeying between tenants

Both models are published with the cylinder removable for rekeying, and with a solid brass cylinder. That pairing is what makes a deadbolt economical on a rented building: when a tenant leaves, the cylinder comes out and is re-pinned to a new key instead of the whole lock being replaced. It is also why keying belongs in the order rather than after it: a deadbolt ordered to match the lever set on the same door should arrive in the same keying group, and a building that expects to rekey often should say so, so the keying plan leaves room for it.

What the rest of the family publishes, and what it does not

The D101 is published in several finishes, including antique brass (US5), antique copper (US11) and polished brass; the D102 in antique copper (US11), polished brass (US3) and satin stainless steel (US32D). For an exterior door in a coastal climate, satin stainless is the finish to ask about first, and it is worth asking which trim material comes with it, since the trim is published as stainless steel, brass or steel. There is also a Keyed Deadbolt Lock Set, published with the same core specification: 25mm throw with the hardened steel roller insert, 5-pin tumbler with a solid brass plug, free-turning trim and keying to pair with an entrance lock.

Two records in the family publish nothing at all: the D01 AB and the D103 AC carry photographs and no specification rows. We are not going to fill them in from their neighbors. They may well share the D101's throw and backset, but a throw copied from a similar-looking deadbolt is a number nobody tested. If either is the one you want, ask and we will measure it.

Comparing two deadbolt quotations

Two deadbolts at different prices usually differ in rows that do not show in a photograph, so compare them row by row rather than by picture. The rows that matter, in the order they matter: the throw (25mm or less); an anti-saw insert in the bolt, and what it is made of; free-turning trim around the cylinder; the cylinder, pin count, and whether the plug is solid brass or a casting; whether the cylinder is removable for rekeying; the backset and door-thickness range; the number of keys; and whether it can be keyed to the lock above it. Our D101 DSPB publishes every one of those rows; the D102 records publish all of them except the pin count, which we will confirm on request. A quotation that leaves several of them blank is not necessarily a worse lock, but it is a lock you are being asked to buy without knowing.

For a quotation: the door thickness, whether the deadbolt is single or double cylinder, and whether it is keyed with the lock above it. That third one is the question most inquiries leave out and the one that determines how the keys arrive.