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DESIGN GUIDELINE

Heat-Set Insert Design Guide

We press knurled brass inserts into 3D-printed parts with a heated tip, giving plastic parts durable metal threads that hold up to repeated assembly. Model your holes to this guide and your inserts will sit straight, flush and secure, with a faster turnaround.

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01 · SIZE CHART

Size Specifications

Swipe to scroll the table →

ThreadInsert ODDLengthsLHole Dia.ØDMin. Hole DepthH ≥ L + 1Min. WalltCenter to Edgemin. eInsert Spacingmin. p
M22 ODs3.032.641.53.06.0
3.22.5 / 3 / 42.83.5 / 4 / 51.53.07.0
M2.53.54 / 53.15 / 61.63.57.0
M32 ODs4.65.74.06.71.84.010.0
5.04 / 5 / 64.45 / 6 / 71.84.010.0
M46.04 / 6 / 85.35 / 7 / 92.25.012.0
M57.06 / 7 / 106.37 / 8 / 112.56.014.0
M62 ODs8.087.393.07.016.0
9.088.393.07.518.0
1/4"-20tripod thread8.012.77.313.73.07.016.0

All dimensions in mm. The table lists the double-knurled brass heat-set inserts we stock. M2, M3 and M6 each come in two outer diameters, so size the hole for the insert you actually choose; if unsure, check with us first. Where one OD comes in several lengths, match the hole depth to the chosen length (e.g. M3, OD 5.0, length 6 → hole depth ≥ 7). If no length is specified, we use the longest insert that fits within the hole depth.
Model holes at the "Hole Dia." value as listed. There is no need to compensate for print shrinkage; for special materials or tight tolerances, we fine-tune as needed.

02 · CROSS SECTION

Hole Cross-Section

Insert L ØD H L Gap ≥ 1 mm t (≥ min. wall) Chamfer Part surface
ØDRecommended hole diameter: a straight hole with no draft, 0.4–0.7 mm smaller than the insert OD, so the plastic displaced during pressing locks into the knurling.
HHole depth: for blind holes, at least insert length + 1 mm, giving the molten plastic somewhere to flow so the insert seats fully instead of being pushed back out.
LInsert length: finishes flush with the part surface after installation (0–0.2 mm recess allowed).
tWall thickness: the solid material between the hole and the part's outer edge. Too thin and it will bulge or crack.
CEntry chamfer 0.3–0.5 mm: helps alignment and prevents a burr from forming at the hole edge.

03 · DESIGN TIPS

Design Tips

Hole Orientation

  • Keep the hole axis perpendicular to a flat face; the heated tip presses straight down from above. For holes on slopes or curved surfaces, add a flat landing.
  • Leave clearance above the hole of diameter ≥ insert OD + 6 mm and 15 mm height so the heated tip can reach it.
  • Align holes with the print direction (printed facing up) for the roundest, most accurate hole walls.

Hole Shape

  • A straight hole is all you need, with no taper. Blind holes can have a flat or conical bottom.
  • Through holes are fine too, but the back side needs a supporting surface, or tell us how deep the insert should go.
  • Keep supports out of the holes; redesign horizontal holes ≤ 10 mm in diameter into a support-free shape.

Strength & Spacing

  • Do not go below the size chart values for wall thickness, center-to-edge distance or insert spacing.
  • For high loads or frequent disassembly, choose the next size up or a longer insert of the same thread.
  • Surround inserts with solid material or a thickened boss rather than relying on a thin shell.

Marking Your Holes

  • In your file or a reference image, mark the thread size and quantity for each hole, e.g. "M3 × 8".
  • If one part uses several sizes, distinguish them by color or number.
  • Note separately any specific insert length, OD, or a height other than flush.

04 · MATERIALS

Suitable Materials

GOODPLA / PLA+The most common choice; installs at about 200–220 °C with a high success rate. For parts exposed to sustained heat (> 50 °C), consider PETG or higher.
GOODPETGTough and crack-resistant; installs at about 230–245 °C.
GOODABS / ASA / PCGood heat resistance and the firmest insert grip; ideal for mechanical and outdoor parts.
GOODPETG CF / PA CFInserts can be installed, but carbon-fiber materials need a slightly adjusted hole size. Please check with us first.
AVOIDTPU (flexible), resin partsFlexible filaments cannot hold an insert in place; cured photopolymer resin does not soften with heat and cracks easily, so heat-setting does not apply.

05 · PRINT SETTINGS

Print Recommendations

Applied automatically when we print your parts.

Walls & Infill

  • Wall loops: at least 3–4, so the area around the hole is solid.
  • Infill: 25% or more recommended; 40% or more for load-bearing parts.
  • Keep at least 1 mm of solid bottom layers below the hole.

Troubleshooting

  • Tilted insert: the hole isn't perpendicular or clearance is insufficient. Check hole orientation and the space above it.
  • Bulging or cracking around the insert: wall thickness or edge distance is too small, or the hole is undersized.
  • Insert spins or pulls out: the hole is oversized or not deep enough.

06 · PROCESS

How It Works

  1. Send files or parts: upload STEP / STL files (holes modeled to this guide), or ship us parts you have already printed.
  2. Mark hole locations and sizes: include the thread size and quantity for each hole (an annotated screenshot is fine).
  3. Design review: we check hole diameter, depth and wall thickness against this guide and suggest changes if anything is off.
  4. Installation & inspection: each insert is heat-pressed individually, checked for squareness and flushness, and test-fitted with a screw.
  5. Packing & shipping: choose convenience-store pickup (Taiwan), home delivery or studio pickup.

07 · CHECKLIST

Pre-Submission Checklist

Questions about your design? Send it over

Share a file or screenshot and we'll help confirm hole placement and insert sizes, or upload your model for an instant quote.

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