Every setting, and what it actually does
Most of these change the numbers on your cutting sheet. Two of them change whether the parts fit at all. This page shows what each one does, and draws the geometry the plan is built on, so you can check the plan against the drawing on your bench before you cut anything.
Kerf, the blade eats material
Every cut turns a sliver of the bar into dust. That sliver is the kerf, and it is the width of the blade. Cut ten 600 mm parts out of a 6 m bar with a 3 mm blade and you need 6,027 mm of bar, not 6,000, which is why the tenth piece comes up short if nobody told the plan about the blade.
How to set it: measure a finished cut, or read the blade. Drop-saw blades are typically 2-3 mm; thin metal cut-off discs 1-2 mm; an 1/8" blade in inch mode is just 1/8. Shearing or snapping removes nothing, leave it at 0.
End trim, mill ends are not square
Stock arrives with ends that are rough, painted, out of square, or damaged from the rack. Switch end trim on and the plan takes one blade width off each end of every bar before it measures anything, so parts start from clean material.
Mitres & angles
This is the setting people get wrong, and it is the one that costs real material when they do. The rule is short: an angle is measured inside the piece, off its longest face. Everything else follows from that.
45° and 135° are different pieces
They are the same cut on the saw and the opposite piece in your hand. The long face tells them apart: at 45° the piece leans in over its long face, at 135° it leans out.
Shortcut: if you have the top angle instead, because that is what the drawing gives you, type it as a negative number. -45 means "the top angle is 45", and the plan works out the bottom for you (180 − 45 = 135).
Why it asks for the material width
A square cut is a line. An angled cut is a ramp: it enters the near face at one place and leaves the far face somewhere else, and how far apart those two places are depends entirely on how wide the material is. Without the width there is no way to know how much bar a mitre consumes, and the plan would be a guess.
Two parts meeting: one cut, or two and a wedge
When the facing ends of two neighbouring parts are parallel, one pass of the blade makes both, the plan puts them together and you get the cut for free. When they are not parallel, both ends have to be cut and the triangle between them drops out as waste. That wedge is real material, and it is why a job full of opposing mitres uses more bar than the arithmetic suggests.
Symmetry: may the plan turn a part over?
This is the setting that pays for itself, and the one nobody touches because the name means nothing. Here is what it actually does.
Take a 920 part mitred 45° at both ends. Lay two of them nose to tail the obvious way and the two sloping ends run away from each other: the saw has to make two cuts, swinging from one side to the other, and the triangle between them drops on the floor. Turn the second one over and the ends become parallel. One cut makes both. The blade never moves, and the pair takes up 100 mm less bar.
Whether the plan is allowed to do that is a question about your material, not about geometry, and only you can answer it. A square tube can be turned any way you like and it is the same part. An extrusion with a face, a channel, a pattern, a weld seam or a coated side cannot. Axial symmetry names the axes your material can be rotated 180° about without changing what it is, and the plan will only use the flips you allow.
| Setting | What the plan may do | Use it when |
|---|---|---|
| None | Nothing. Every part is cut exactly as entered. | The material has a face, a pattern, a seam or a coated side. |
| X | May turn a part over, so its top face becomes its bottom. | The section is symmetric, but the two ends are not alike. |
| Y | May swap a part end for end. | The section has a top and a bottom, but the ends are alike. |
| Z | May rotate a part 180° in the plane, which is both of the above at once. | The section is symmetric about its own length. |
| XYZ | Any of it. The plan has a free hand, and will use it. | Square and round tube, plain bar, solid rod. |
What that looks like in the rack
Square & round tube, plain bar, rod
XYZ
Nothing tells one face from another and nothing tells one end from the other. The plan has a free hand. This is where flipping pays.
Rectangular tube, flat bar
XYZ
Symmetric about both axes, so long as you do not care which face ends up uppermost. If one face is the "good" one, treat it as a face and say none.
Angle iron, channel, T-section
Y only, or none
It has an up. Turn it over and the leg points the wrong way. You may still swap it end for end (Y) if both ends are alike, but never flip it.
Extrusion with a groove, slot or key
None
The groove has to end up where the drawing says. A flipped part is a mirror-image part, and it will not go together.
Anodised, powder-coated, veneered, grained
None
The finish is on one side. So is the pattern, the print and the grain. Turn it over and you have scrap with a nice back.
Seam-welded tube, mill-marked stock
X or Y, rarely XYZ
Round, but the seam is not. If the seam has to face a particular way in the finished job, it is a face like any other.
When in doubt, say none. A plan that never turns anything is always cuttable. A plan that turns a part you cannot turn produces a pile of mirror-image scrap, and you will not find out until the parts refuse to go together.
Method, what "best" means to you
Every method returns a plan that fits. They disagree about what to spend to get there.
| Method | Optimises for | Use it when |
|---|---|---|
| Balanced | Fewest bars, then least waste | The default, and right for most jobs. |
| Least waste | The smallest total offcut | Material is expensive and the bar count is not the constraint. |
| Offcuts first | Clearing the rack | You are drowning in short ends and want them gone. |
| Fewest setups | The fewest distinct saw-stop positions | Setting the stop costs more than the steel, long runs, one operator. |
| Cheapest | Money | You buy several stock lengths at different prices. Needs a price on at least one stock, with no prices there is no cost to optimise. |
Offcuts and the remnant threshold
Offcuts are the useful ends already on your rack: tell the plan about them and it will cut from them before it buys anything. The minimum remnant is the other half of that conversation, the shortest leftover you would actually keep. Anything shorter is counted as waste, and the plan stops carefully preserving 40 mm stubs that you will sweep up anyway.
Material groups
One job, several materials. Tag a part with a material and it will only ever be cut from stock and offcuts carrying the same tag, a 40×40 upright is never planned out of a 50×25 rail, however neatly the numbers would have worked out. Leave the tags empty and everything is one pile, which is what you want for a single-profile job.
Units and fractions
The unit is mostly a label: use anything you like, as long as every field uses the same one. The exception is inches (fractions), which lets you type 15 3/4 or 1' 3 3/4 in any field, kerf included, and gives results, diagrams and PDFs back as fractions rather than as 15.75.