Tab and Slot Clearance for Laser-Cut Sheet Metal
Tab and slot clearance for laser-cut sheet runs about 0.003-0.005 in per side up to 1/8 in, more for plate or coating. Starting points and test fits.
Self-locating parts are great until the tab won't go in. Tab and slot clearance is a small number that decides whether assembly takes seconds or a hammer.
How Much Clearance Should a Laser-Cut Slot Have Around Its Tab?
About 0.003–0.005" per side up to roughly 1/8" thick is a common starting point. Go larger for thick plate or coated parts, and cut a test pair before committing.
An r/cad user designing flat-pack furniture, a stool and a chair, asked for a reference on what clearances to use for specific materials. It's a common question, and the published answers mostly come from fabricators.
Published tab and slot clearance figures
SendCutSend's tab and slot guide gives a table by thickness: .003" per side for .060" sheet, .005" for .125", and .010" to .020" for .250" plate and up. So up to about 1/8" it runs .003–.005" per side. It calls .005" per side a great starting point and says to add another two or three thousandths per side for powder coating.
Fictiv's design article gives a broader rule of 0.1–0.2 mm per side, tighter for laser cutting. It also suggests keeping slots at least 1.5× thickness away from a bend tangent.
Those numbers roughly agree. The thickness is what changes the answer.
Why the sheet isn't the drawing
Sheet thickness varies within its tolerance, so a slot drawn to nominal can be tight on a thick sheet. Laser edges also taper slightly on thicker material, which is covered in why laser cutting leaves a tapered edge. For narrow features, cutting a slot vs drilling the ends matters too. If the part is bent as well, be clear about inside vs outside dimensions.
Design the slot as a parameter tied to thickness. Then changing gauge doesn't mean redrawing every slot.
Getting it cut
Our sheet metal capability page lists laser cutting with "±0.13 mm cut, ±0.5° bend angle". That ±0.13 mm is about 0.005", roughly the same size as the clearance itself, so test fits matter. For the slot clearance we'd suggest at your thickness, ask us when you quote.
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