How do you cut square tubing straight without a chop saw?

Clamp a speed square across the tube as a fence, set back from your line by the distance from the saw's shoe edge to the blade. Run the portable band saw's shoe along the square and the blade follows the line.

How far back do you set the guide for a portable band saw?

By your own saw's offset: the distance from the edge of the shoe that rides the guide to the near face of the blade. It varies by model, so measure it with the shoe in its cutting position and confirm it on a scrap cut.

Which side of the line does the guide go on?

The keep side, measured to the near face of the blade. That way the kerf lands in the waste and the piece you keep is the length you marked.

Why is my portable band saw cut not square?

Freehand cuts drift on the top face, and tilting the saw throws the sides out of square. A clamped fence fixes the top. Keeping the saw upright as the blade goes down the side walls fixes the rest.

Cutting, Not HackingMetal & PipeSpeed square Portaband guide

How do you get a square cut on tubing with a portable band saw?

No chop saw, a stack of square tube, and a Portaband. Freehand, the blade wanders. Not much, but 1° off square across a 2 in (51 mm) face is just over 1/32 in (0.9 mm) of gap at the joint, and you'll be filling that with weld. Adam Fleisch clamps a speed square to the tube and lets the saw's own shoe ride it like a fence.

A portable band saw has an exposed blade in its throat and throws hot, sharp chips off metal. Wear eye protection, clamp both the tube and the square so neither can move, keep your hands out of the throat and clear of the blade path, and let the blade stop before you lift the saw out of the cut. Fresh-cut tube edges are razor sharp: deburr before you handle them bare-handed.

⚡ Rule of thumb

Clamp a speed square across the tube as a fence, set back from your cut line by the distance from the blade to the edge of the saw's shoe, on the keep side. Run the shoe along the square the whole cut and the blade tracks your line square instead of wandering.

Starting point

Fence offset = your saw's shoe-edge-to-blade distance, measured · square clamped, not hand-held

Measured

From the edge of the shoe that rides the square to the near face of the blade, shoe in its cutting position

Confidence

Creator technique

▶ Source video — Need a straight cut on square tubing without a chop saw? — Adam Fleischwatch on Facebook ↗

Applies to

Process: Metal cutting and fabrication without a chop saw or horizontal bandsaw
Materials: Square and rectangular tube, flat bar, angle; anything with a flat face for the square to sit on
Setup: Portable band saw, speed square, quick clamp or bar clamp, tape, marker
Orientation: Tube clamped to the bench, square flat on the top face with its lip hooked over the near edge

Why it matters

An out-of-square cut doesn't stay a small problem. Butt two of them together and the gaps add up, then you're grinding the ends back or bridging the gap with filler and hoping it looks intentional.

A speed square already has a lip that hooks the tube's edge, so it sits square to the side the moment you set it down. Clamp it, and you've got a straight fence for free. The only number you need is how far the blade sits from the edge of the shoe.

Measure it once.

Write it on the saw. Every cut after that is set the square, clamp, cut.

What good looks like

The kerf runs along the line on the top face, in the waste
The cut end checks square against the speed square
Butt joints close up with no daylight
The shoe stayed against the square from the first tooth to the last

How to apply it

Mark the cut line square across the tube with the speed square.
Measure your saw's offset: from the edge of the shoe or guard that will ride the square to the near face of the blade. Measure with the shoe in its cutting position, since some guides retract.
Set the speed square that offset back from the line, on the keep side, lip hooked over the tube edge.
Clamp the square to the tube. Clamp the tube to the bench.
Rest the shoe against the square's edge and cut, keeping it in contact the whole way through.
Check the cut end with the square, against two neighbouring faces.

Test it on your setup

Offset check: cut a piece of scrap first and measure where the kerf landed against the line. Adjust the offset once, then mark the final number on the saw.
Square check: hold the speed square on the cut end against the top face and against a side face. The fence controls the top. The sides are you holding the saw plumb.

Exceptions & tradeoffs

The fence only steers the blade across the top face. Down the sides, square depends on keeping the saw upright, so watch the blade, not the shoe, as it comes through the side walls.

Retracting or sprung guides change the effective offset. Measure with the shoe where it sits mid-cut, not where it parks.

Mind you, it's only as accurate as three things: the line, the offset, and the clamp. A square that creeps 1/16 in (1.6 mm) moves the cut 1/16 in.

For a run of identical cuts, a chop saw, a cold saw or a Portaband table is faster. This is the method for when you've got the saw in your hand and nothing else.

Common mistakes

Setting the square right on the cut lineSet it back by the shoe-to-blade offset
Fencing on the waste side, then cutting the keeper short by a kerfFence on the keep side and measure to the near face of the blade, so the kerf falls in the waste
Holding the square with your other handClamp it. The saw pushes it, and your hand ends up near the blade
Trusting a remembered offset after a blade or guide changeRe-measure after any blade change and re-mark the saw

Frequently asked questions

How do you cut square tubing straight without a chop saw?Clamp a speed square across the tube as a fence, set back from your line by the distance from the saw's shoe edge to the blade. Run the portable band saw's shoe along the square and the blade follows the line.
How far back do you set the guide for a portable band saw?By your own saw's offset: the distance from the edge of the shoe that rides the guide to the near face of the blade. It varies by model, so measure it with the shoe in its cutting position and confirm it on a scrap cut.
Which side of the line does the guide go on?The keep side, measured to the near face of the blade. That way the kerf lands in the waste and the piece you keep is the length you marked.
Why is my portable band saw cut not square?Freehand cuts drift on the top face, and tilting the saw throws the sides out of square. A clamped fence fixes the top. Keeping the saw upright as the blade goes down the side walls fixes the rest.

Adam FleischSource & visual reference

A clamped speed square, set back from the line, used as a fence for a portable band saw's shoe on square tube — Need a straight cut on square tubing without a chop saw? ↗ at 0:16–0:54.

Summarized and independently edited by Start Here from Adam Fleisch's Facebook reel: sampled frames and the on-screen captions, no audio. The clamped speed square as a shoe fence is clearly his. His saw's actual offset isn't readable on screen (the caption only says "over another inch"), so I've left it as a number you measure on your own saw rather than quoting his. The side-wall caution, the gap arithmetic, the safety notes and the test steps are mine.