Models / Kerf and fit test

Kerf and fit test

Slots from a little narrower to a little wider than the material. Push a scrap of the same sheet into each slot: if the one marked 0 is snug, $kerf and $thickness are right. If a + slot fits best, your material is thicker than you said; if a - slot does, it is thinner.

The cut file as the downloads lay it out: 87.2 × 33.2 mm, 1 part on 1 sheet. Rendered by KerfScript 0.2.0 from the source below.

Open in playground kerf-test.kerf SVG DXF

Parts

Part	Qty	Size
part	1	81 × 27 mm

Settings

Setting	Default	Range
`$thickness`	`3`	1 to 10
`$kerf`	`0.15`	0 to 0.5
`steps` How many slots	`7`	3 to 11
`step` Change in width from one slot to the next	`0.1`	0.05 to 0.3
`depth` How deep the slots go	`15`	8 to 30

Check cut order, power, speed and material settings in your laser software before cutting. Laser software notes

Source 30 lines

// Slots from a little narrower to a little wider than the material.
// Push a scrap of the same sheet into each slot: if the one marked 0 is
// snug, $kerf and $thickness are right. If a + slot fits best, your
// material is thicker than you said; if a - slot does, it is thinner.
 
/* [Material] */
$thickness = 3; // [1:0.5:10]
$kerf = 0.15; // [0:0.01:0.5]
 
/* [Slots] */
// How many slots
steps = 7; // [3:2:11]
// Change in width from one slot to the next
step = 0.1; // [0.05:0.05:0.3]
// How deep the slots go
depth = 15; // [8:1:30]
 
pitch = $thickness + 8;
width = steps * pitch + 4;
deltas = [for (i = [0:steps - 1]) round((i - (steps - 1) / 2) * step * 100) / 100];
 
difference() {
  rect([width, depth + 12], r = 2);
  for (i = [0:steps - 1])
    translate([pitch / 2 + 2 + i * pitch - ($thickness + deltas[i]) / 2, 12])
      rect([$thickness + deltas[i], depth + 1]);
}
engrave() for (i = [0:steps - 1])
  translate([pitch / 2 + 2 + i * pitch, 4])
    text(str(deltas[i] > 0 ? "+" : "", deltas[i]), size = 3.5, halign = "center");