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Lesson 1 of 8

The machine families: where each saw fits

The first cut decides most of what follows

The machine that breaks a log into boards, cants or flitches sets the sawdust loss, the dimensional accuracy that downstream edgers and planers must live with, the processing speed and the kind of logs the mill can handle. Oklahoma State University Extension (USA, 2017) describes the headrig as the machine centre that strongly affects overall mill productivity. It has four jobs: determine log geometry and grade, orient and fix the log, transport it, and cut it.

Today a headrig may be a single band saw on a carriage, twin or quad band saws, a canter line with circular saws, a sash gang, or a chipper-canter line.

The five families

Family	Principle	Typical strength	Typical weakness
Band saw	Thin flexible steel loop on two wheels, kept in tension	Thin kerf, flexible log handling, relatively low cost	Accuracy depends heavily on setting and maintenance
Circular saw	Rotating disc, stiff, tolerates high feed speed	Speed: resaws, canter lines, edgers, trimmers	Disc must be thick enough to stay flat, so large headsaws cut wide kerf
Frame (sash gang) saw	Many parallel blades in a reciprocating frame, whole cant sawn in one pass	Straight, consistent cuts from rigid guidance	Low feed speed per frame, relatively thick blades
Chipper-canter / profiling line	Mills the outer slabs off as chips, then saws the cant	Small softwood logs, chips as saleable by-product	Needs scanning and automation; open yield comparisons are thin
Curve sawing	Scanner steers the cut to follow log sweep	Sweepy logs give higher yield	Needs scanning investment

The OSU Extension text calls band saws the most widely used headrig in many mills and multiple circular resaws the most widely used secondary breakdown machine.

Matching machine to mill

The portal's machinery article offers a decision guide. It is the author's synthesis, not a measured ranking:

Small hardwood mill, variable logs, grade lumber: band headrig, thin kerf, operator decisions.
Small softwood or mixed mill, low capital: band mill or circular resaw, manual or semi-automatic edging, green chain.
Mid-size softwood mill: twin or quad band, or canter with circular saws, scanner-guided edger, drop sorter.
Large softwood plant, small to medium uniform logs: chipper-canter or profiling line, curve sawing, automated edging and trimming.
Uniform small logs, few stable dimensions: frame saw or gang line can be competitive.

European canter lines suit uniform plantation logs sorted into many size classes; a 2004 trade column argued that North American log supply is too variable for that, so machines there are set per log. That is a regional, dated opinion, not a law.

Feed speed is not throughput

Feed speeds quoted in the sources vary widely and come from different kinds of evidence:

Band saw: about 66 to 110 m/min in software tutorial examples (USA, 2009; ft/min converted with 1 ft = 0.3048 m).
Circular saw: about 53 to 101 m/min in the same software examples.
Frame saw: up to 20 to 25 m/min, a manufacturer quote cited in a paper.
Chipper-canter: 20 to 150 m/min in a German vendor brochure (2020), a vendor claim.

A frame saw cuts many boards per stroke, so it cannot be compared with a single blade by feed speed alone. Software examples are not field measurements, and vendor figures are maximums under ideal configurations.

Worked example

A mill buyer is told "line A feeds at 200 ft/min, line B at 22 m/min". Convert: 200 ft/min is 200 x 0.3048 = 61 m/min. Line A is faster per blade, but if line B is a frame saw with dozens of blades, the comparison tells nothing about boards per minute. The right question is boards or cubic metres per hour under your log mix, plus recovery and accuracy.

Checklist before comparing machines

Are the figures from measurement, software, a trade column or a vendor?
Which country and year?
Is the figure a maximum or an average?
Is the unit feed speed, or output of finished product?

Key points

The headrig strongly affects overall mill productivity and sets sawdust loss and accuracy for everything downstream.
Band saws favour thin kerf and flexibility; circular saws favour speed; frame saws favour straight, consistent cuts; chipper-canters favour small softwood logs.
The decision guide is a synthesis, not a ranking.
Compare feed speeds only with their source type in mind, and never as a stand-in for throughput.

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