Binding Planner Schematic
A case is the hard cover of a book: two boards and a spine inlay glued to one piece of covering material, made apart from the pages and fitted to the sewn text block. This page takes the block's measurements and works out the board size, the spine inlay width, the joint gap and the covering material to cut, then draws a schematic you can print with the cutting list on its second page. Nothing is uploaded and no account is needed.
Your text block
Flat back only. A rounded spine needs a wider inlay than these numbers give, because the curve adds to the width the inlay has to cover.
One page, spine to fore-edge, after trimming.
One page, head to tail, after trimming.
Measure the sewn block at the spine with a caliper or a ruler, endpapers on.
The greyboard or millboard you will cut the covers from.
Book cloth is about 0.5 mm (0.02 in). Paper is thinner and leather thicker.
Turn-in and square
The margin of covering material folded over each board edge.
How far the boards overhang the pages at the head, tail and fore-edge.
Cut to these sizes
- Boards, each (W x H)
- 148.5 mm x 216.0 mm
- Spine inlay width
- 17.0 mm
- Joint gap, each side
- 6.0 mm
- Board to board
- 326.0 mm
- Covering material (W x H)
- 356.0 mm x 246.0 mm
- Square
- 3.0 mm
- Turn-in
- 15.0 mm
Cutting list
Grain runs parallel to the spine on every piece. The mull that lines the spine and laps past the joints onto both sides is not on the list.
| Part | Qty | Width (mm) | Height (mm) |
|---|---|---|---|
| BoardsCut both from the same board so they match. | 2 | 148.5 | 216.0 |
| Spine inlayThinner card than the boards, cut to the same height. | 1 | 17.0 | 216.0 |
| Covering materialIncludes the turn-in on all four sides. | 1 | 356.0 | 246.0 |
| EndpapersOne sheet per board, folded once at the spine to the trim size. | 2 | 296.0 | 210.0 |
The PDF prints in millimetres on any paper size. It is a drawing with the numbers on it, not a template to cut against.
The schematic
How the numbers are worked out
The board width is the trim width, less one board thickness, plus the square. The board height is the trim height plus two squares, one at the head and one at the tail. The spine inlay is the text block thickness plus two board thicknesses, so it spans the block and the two boards that sit either side of it.
The joint gap is twice the covering material thickness plus 4 mm, and never less than 6 mm. It is the strip of bare material between each board and the inlay that lets the cover open. The covering material width is two boards, plus the inlay, plus two joint gaps, plus two turn-ins. Its height is the board height plus two turn-ins.
These are craft-practice formulas, not measured rules, and they have been validated on one case so far. Check the swing of the cover on your first case and widen the joint gap if it binds.
Have the PDF? Folio imposes it into signatures and fills these numbers in from the page count.
Questions binders ask
What is a case in bookbinding?
The case is the hard cover made separately from the pages: two boards and a spine inlay glued to one piece of covering material, with the material turned in over the board edges. The sewn text block is glued into it afterwards, which is why the case is sized from the block and not the other way round.
How do I measure the text block thickness?
Close the sewn block with its endpapers on, press it gently the way it will sit in the case, and measure across the spine folds with a caliper or a steel rule. Take the reading at the spine, not the fore-edge: the sewing thread swells the spine a little and that swell is what the inlay has to cover.
Why is the board narrower than the page?
The board width is the trim width minus one board thickness plus the square. The board thickness comes off because the board sits back from the spine edge of the pages by about its own thickness to leave room for the joint to bend. The square goes on so the fore-edge overhangs the pages by the same lip as the head and tail.
Does this work for a rounded spine?
No. The numbers are for a flat back only. Rounding the spine widens it by the curve, so a rounded book needs a wider inlay and a wider joint than these formulas give, and the extra depends on how far you round it.
Which way should the grain run?
Parallel to the spine on every piece: boards, inlay, covering material and endpapers. Paper and board expand across the grain when they take on moisture from the glue, and a piece with its grain running the wrong way warps the board or cockles the page after the case is made.
Are these numbers proven?
They are the working formulas binders use, and they have been checked on one case so far: a journal with a 14 mm block, 3.1 mm boards and cloth at 0.5 mm, which fitted. Treat the joint gap as the number to check first on your own materials, and adjust it if the cover does not open freely.