Hardwood Dimension Stock: Cut Size Specs, Face Rules and Yield Math

Dimension stock is hardwood cut to the size of the part before it reaches your plant. That changes what you write on the order. For lumber, the grade rule carries most of the spec. For dimension stock, the part drawing carries it, and the grade only tells you what the mill started from. This page lists what a dimension order should state and shows the arithmetic that sets the price.

Spec line	What to write	Why it matters
Species and botanical name	Hard maple (Acer saccharum), not just “maple”	Species changes hardness, color and the paperwork
Finished size	Thickness x width x length, with a tolerance	The part you will machine next
Rough or surfaced	Rough, S2S, S4S or ripped and crosscut only	Decides the oversize allowance
Face rule	Which faces must be clear, which may show sound defects	Replaces the lumber grade for the part
Blank type	Solid, edge glued or face glued	Glue lines, color match and moisture risk
Moisture	Target and upper limit, with the test method	Parts move after cutting if the stock is wet
Count and tally	By piece, with spare allowance	Dimension is bought by the part, not by the board
Packing	Bundled by size, end sealed, labeled	Protects the stock and speeds receiving

What NHLA grades cover and what they do not

NHLA grades describe lumber that will be cut into smaller pieces. A board’s grade depends on how much of it can be cut into clear pieces of a minimum size. The factory grades, FAS, F1F, Selects, No.1 Common and No.2A Common, are clear face cuttings grades, and No.2B Common is the sound cuttings grade, where sound defects are admitted in the cuttings. Our NHLA grades guide and the Selects and F1F page show the numbers.

The USDA and extension summaries that describe these grades say plainly that a summary is not the full rulebook. The rulebook holds exceptions by species and special rules. No public, widely cited grade set for finished dimension parts turned up in the sources used for this page, so the page does not quote one. Do this instead:

1. Name the rulebook edition if you refer to NHLA at all.
2. Write the face rule for the part in your own words: for example “both faces clear, edges and ends sound” or “one face clear, reverse face sound defects allowed”.
3. Attach the drawing or a photo of an accepted part.

That is how a buyer and a mill agree when no published dimension grade is named. It is also how a cabinet or furniture plant writes the same rule twice, once for the show face and once for the hidden face.

From lumber grade to part yield

A dimension order is a yield problem. The mill chooses a grade of board, cuts out the clear pieces and discards the rest. The cost per part is the cost of the board divided by the parts it yields, plus the cutting.

The arithmetic uses board feet. One board foot is 144 cubic inches of finished volume.

Step	Example part	Result
Part size, finished	3/4 x 2 1/2 x 30 in	56.25 cubic inches
Board feet per part	56.25 / 144	0.39 bf
Parts needed	1,000	390.6 bf of finished parts
Rough lumber at 50% yield (illustration)	390.6 / 0.50	781 bf of rough
Rough lumber at 40% yield (illustration)	390.6 / 0.40	977 bf of rough

The yield figures are illustrations, not typical values. Real yield depends on species, grade, part size, kerf and planing losses and how the mill cuts. The point is that a 10-point yield change moves the rough lumber need by about a quarter. A lower grade of board at a lower price per board foot can cost more per part, and a higher grade can cost less. Ask the mill for its yield basis or for a price per piece, and compare quotes on the part, not on the board.

The same logic explains why Common grades exist. The upper grades suit long clear work, and the Common grades are meant to be cut into shorter clear pieces. That favors Common grades for short parts. For long parts, such as stair stringers or door stiles, the upper grades give more usable length per board. Our guide to rough lumber versus S4S versus dimension parts compares the product forms. The guide to straight line rip and gang rip edge options covers how edges are prepared before cutting.

Sizes and oversize allowance

Write the size twice: the finished size you need and the size the mill ships.

• Finished size and tolerance. For example 3/4 in thick, plus or minus an agreed amount, measured at a stated moisture.
• Rough oversize. If your plant planes and rips the parts, the mill ships oversize in thickness, width and length. The allowance depends on your machines and on how much the stock will move, so agree it on the order.
• Crosscut or random length. Say whether the parts are cut to length, cut to a length range or sold in random lengths with a minimum.
• Imperial and metric. The NHLA rules are written in inches and feet. If your drawing is metric, give both units and say which one is the reference.

Solid, edge glued and face glued blanks

A blank is a piece cut or glued to a size larger than the part.

• Solid blanks come from one board. Color and grain match within the part, and width is limited by the board.
• Edge glued blanks join strips side by side to make a wider panel. The spec should name the glue line spacing, the color match rule and how strips are arranged for balance.
• Face glued blanks build thickness by laminating boards flat. They are used for legs and thick parts. Name the number of plies and the grain direction.

Name the adhesive type if the part has a service condition such as moisture or heat. Do not rely on the word “glued” alone.

Defects, color and sorting

Face rules are easiest to set when you list what you accept and what you refuse:

Item	Common ways to write it
Knots	None on show faces. Sound tight knots up to a stated size on hidden faces
Stain and color	Natural color variation accepted. Sticker stain, mineral streak or sapwood limits stated per species
Checks and splits	None through the part. End checks removed
Wane	None on finished dimension
Worm holes	Pin holes accepted on hidden faces only, or none
Heartwood and sapwood	Mixed, sapwood only or heartwood only for colors that matter

For species where color matters, such as hard maple (white sapwood) or walnut (dark heartwood), also say whether a color sort is required.

Moisture and stability

Parts cut from drier wood stay closer to size. Ask for a moisture target and an upper limit, the method that decides disputes and a sampling plan. Our page on lumber moisture test methods explains the oven-dry reference and the meters. Parts that are cut and surfaced should be bundled and wrapped soon after cutting, because thin pieces take up moisture quickly in damp storage. End sealing on long parts reduces end checking in transit.

Tally and receiving

Dimension is counted by the piece. A tally should show quantity by size, plus the spare allowance the order permits. Ask for a count by bundle and a label on each bundle with the size, species and lot. Our guide to hardwood lumber tally covers the habits that carry over from lumber.

On receipt:

1. Count the pieces in a sample of bundles against the label.
2. Measure a sample against the drawing, in all three directions.
3. Check the show faces against the face rule, with the accepted part photo in hand.
4. Check moisture on a sample.
5. Record the result against the order and send it to the supplier the same day.

What a mill can say about itself

Hardwood Vendor does not cut dimension parts, grade them or set any dimension rule. A mill that quotes dimension stock should state its yield basis, its face rule and its tolerance in writing. Ask for a sample or a photo of an accepted part before the first order.

What to write on the RFQ

• Species and botanical name, and the color sort if it matters.
• Part drawing or finished size with tolerance, and the rough oversize if you plane.
• Face rule in words, and the reference photo.
• Blank type: solid, edge glued or face glued, with glue line rules.
• Moisture target, upper limit and test method.
• Quantity by piece, with the spare allowance and the pricing basis (per piece or per board foot of finished parts).
• Packing: bundled by size, end sealed, labeled.

Send your lumber RFQ with the part size and the face rule, and we pass it to up to 3 mills or yards that cut dimension stock.

RFQ line: Hard maple (Acer saccharum), dimension stock 3/4 x 2 1/2 x 30 in S4S, one face clear and reverse sound, solid blanks, KD 6-8%, count 1,000 pieces plus 2%, priced per piece, bundles labeled by size.