Door Hardware Drawings 2026: PDF, DWG, STEP and BIM Compared, and What a Factory Can Actually Give You

"Can you send the CAD?" is the most common technical request a hardware factory receives and the least specific. CAD is not a format, and the three things people mean by that sentence need three different files.

The cost of the ambiguity is a week. A buyer asks, a factory sends what it has, the buyer discovers it will not do what they needed, and the exchange restarts with better words that could have been used the first time.

Three drawings that answer three different questions

Before the format, decide which question you are asking. Almost every mismatched request is really a mismatch here.

A general arrangement will not let you cut a door. A template will not tell you whether the lever clears a return wall. Asking for "a drawing" and receiving the wrong one of these three is not the factory being unhelpful; it is the question having three answers.

The formats, and what each is honestly for

The row worth reading twice is the last one. A BIM family is not a file format conversion of a drawing — it is a modelled object carrying parameters, and producing it is a separate piece of work with its own cost. A factory that says "yes" to BIM and sends a PDF renamed has not misunderstood the format; they have deferred the discovery.

Why a 3D solid often does not exist

This surprises people, and it is worth explaining because it is not a sign of an unserious factory.

A great deal of hardware is designed and tooled in 2D. The die is cut from 2D profiles, the machining is programmed from 2D, and the part is inspected against 2D drawings. Nobody ever needed a solid model, so nobody made one.

That means a request for STEP can be answered honestly with "that does not exist" by a factory that has made the part for fifteen years and can give you every dimension of it. The correct follow-up is not to doubt them; it is to ask whether a dimensioned 2D drawing will serve, because usually it will.

Where a 3D model genuinely matters — clash detection in a coordinated model, or a machining operation on your side — say what you need it for. A factory that knows the purpose can sometimes produce the specific section you need rather than a whole solid.

A drawing without tolerances is a nominal drawing

Every dimension on a drawing is a target. What a drawing may or may not tell you is how far from that target the real part is allowed to be.

This matters most where two parts have to meet: a lock case in a pocket, a spindle in a follower, a glass fitting on a pane. A nominal 29mm case in a nominal 29mm pocket does not fit; the pocket needs clearance, and the clearance comes from the tolerances rather than from the nominal figures.

So when fit is the question, ask explicitly whether the drawing carries tolerances, and if it does not, ask what the working clearance should be. A factory can answer that from experience even when the drawing does not print it.

What makes a drawing authoritative

A title block with the model number, a revision number and a date. A scale, or an explicit "not to scale". Units stated, once, unambiguously. A projection convention — first angle or third angle — because the same part drawn in the two conventions puts the side views on opposite sides.

What does not make a drawing authoritative: being a screenshot, being a photograph of a printed drawing, or arriving with no revision number. A drawing with no revision cannot be superseded, which means nobody can tell whether it is the current one.

Our own coverage, as a number

Suppliers describe drawing availability in adjectives. Here it is in figures, counted from what is actually on the site.

Eighty-five dimensioned drawings against 924 products is roughly nine per cent, and stating it that way is deliberate. It tells you the honest thing: for most models the specification table is what exists, and a drawing has to be requested and may have to be produced.

The published drawings are SVG, which means they scale to any size without going soft and print cleanly at A3 or A0. They are not CAD source and we do not describe them as CAD.

How to ask so that the first answer is the right one

Name the question, not the format. "I need to check the lever clears a 90mm return wall" gets you a dimensioned elevation; "send the CAD" gets you whatever is nearest to hand.

State what you will do with it. Cutting a door, building a model, comparing two products and writing a schedule are four different needs and three different files.

Say which model numbers, exactly. A drawing request for a range is a request the factory cannot fulfil in one action, and it will come back as a question.

Say the units you work in. We publish millimetres and give imperial equivalents on the English pages, but a drawing dimensioned in both is a drawing with twice the chance of a transcription error, so it is better to know which you want.

When there is no drawing, and you need one anyway

For most of our catalogue this is the real situation, so it is worth saying what to do rather than leaving the reader at nine per cent.

The fastest route is a sample and a caliper. A physical part answers every dimensional question a drawing would, and it answers them for the part you will actually receive rather than for the part somebody drew. Our page on samples and incoming inspection covers what to ask for and what to measure when it arrives.

What happens next is the part that matters, and it is a question of ownership rather than of measurement. A dimension you took off a sample is your measurement. If you put it in a specification and a door is cut to it, responsibility for that number has moved to you — and a factory that later ships a part half a millimetre different has not necessarily done anything wrong, because a nominal and a tolerance were never agreed between you.

So measure the sample, then send the numbers back and ask the factory to confirm them in writing. That converts your measurement into their statement, which is what a drawing would have been. It costs one email, and it is the whole difference between a dimension and an assumption.

Two measurements are worth taking even when a drawing does exist, because they are the two drawings most often leave out. The first is the working clearance a part needs in its pocket or bore, as opposed to its own nominal size — covered above, and the reason a 29mm case does not enter a 29mm pocket. The second is the true projection measured from the finished face of the door rather than from the rose, which is what decides whether a lever clears a return wall.

Both are the difference between a part that fits on paper and a part that fits. Neither takes more than a minute with the sample in your hand, and both are cheaper to establish now than to discover after a container of doors has been machined.

The gap we are not going to paper over

Nine per cent drawing coverage is not a boast. It is the number, and the missing drawings are missing because they have to be produced from the real part rather than generated from a description.

We would rather publish that figure than publish 924 plausible drawings. A drawing is the specification's second draft — the photograph is the first — and a drawn dimension that nobody measured is the same error as an invented figure in a spec table, with the added weight that somebody will cut a door to it.