Which Laser Bed Size? Start With Your Largest Piece

Bed size is the first thing a laser cutter is sold on and the one most often chosen by looking at what a neighbour bought. It does not have to be a guess. It comes from one measurement — your largest pattern piece — and one allowance you add to it.

One measurement, one allowance

Take your largest regular pattern piece and measure its length and its width. Then add clearance on every side: room for the cutting head to travel and for the piece to sit square on the bed. Because the clearance goes on both sides of each dimension, it is counted twice.

A worked example

These figures are made up to show the sum. They are not a recommendation for any unit and not a claim about any machine. They are the values the bed size calculator opens with, so you can check them there.

The largest piece is 70 cm by 55 cm and the clearance is 5 cm a side. The bed has to be at least 70 + 10 = 80 cm by 55 + 10 = 65 cm.

The calculator compares four bed sizes: 900 × 600 mm, 1300 × 900 mm, 1600 × 1000 mm and 1800 × 1200 mm. The smallest, 90 × 60 cm, is long enough at 90 against 80 but not wide enough: 65 does not fit in 60. Turning the piece does not help. The next size, 1300 × 900 mm, fits.

One centimetre can change the bed

Same piece, same four beds, only the clearance changes:

• 2 cm a side: the piece needs 74 × 59 cm and fits the 900 × 600 mm bed, with 1 cm to spare.
• 3 cm a side: it needs 76 × 61 cm. The width now overshoots 60 by 1 cm, and the answer is 1300 × 900 mm.
• 5 cm a side: 80 × 65 cm, 1300 × 900 mm.

One centimetre of clearance decided between two machines. So do not take a clearance from a brochure or a neighbour. Ask the supplier what this machine needs around a piece to sit square and let the head travel, and use that figure.

Rotating a piece

The calculator has a box for allowing the piece to be turned 90°, and it matters. Take a wide piece, 40 cm long and 85 cm across, with 5 cm of clearance. It needs 50 × 95 cm. With rotation allowed it fits the 1300 × 900 mm bed. Without it, the 95 cm side does not fit the 90 cm side of that bed and you need 1600 × 1000 mm.

Rotation is therefore worth a whole bed size in that example — and it is only allowed when the piece has no grain line to respect. A piece cut off-grain to save space produces a garment that hangs wrong after the first wash. Tick the box only for pieces that can genuinely be turned.

What the bed size does not tell you

• How many pieces fit. The calculator checks the largest single piece. A bigger bed holds more pieces in one pass, and the areas are a rough guide: against the smallest, 1300 × 900 is about 2.2 times the area, 1600 × 1000 about 3.0 and 1800 × 1200 exactly 4. How much that matters depends on your marker, not on this arithmetic.
• Whether other sizes exist. Four are compared here. Other makers sell others, and a custom or conveyor machine is an option for pieces larger than any of them.
• The floor. A 1300 × 900 mm machine needs roughly 2.2 m of clear run once you allow for the lid, the exhaust duct and someone standing at the side. Measure your own floor, and confirm the exact footprint with the supplier before you commit.

Before you decide

• Measure your largest regular piece, not an exception you cut twice a year.
• Get the clearance in writing from the supplier, for that machine.
• Decide which pieces may be rotated and which may not.
• Measure the floor, and ask for the full footprint, not just the bed.

Put your own figures into the bed size calculator. The laser cutting guide covers what else to check before the advance, the cost-per-garment calculator works out what the machine costs to run, and the payback and EMI article asks whether it is worth buying at all.