Nut and bolt STL: DIN and ISO fastener 3D models with a torque calculator
Pick one of 36 parts and a size (and a length for 19 of them) and get a 3D model for STL or 3MF, with a true helical thread on 25 of the parts. The handbook works out the tightening torque by strength class.
Opens without an account 3 times a day. A free account removes the limit.
- 36 partsbolts, nuts, washers, pins
- True threadon 25 of 36 parts
- Tightening torqueclasses 4.6 to 12.9
- STL and 3MFfor printing
What a nut and bolt STL from this tool is
This is a free online tool from EduFacturing that builds a 3D model of a bolt, nut, washer, pin or circlip to DIN and ISO and gives it for printing as STL and 3MF. Where a part has a thread (25 of 36) it is a true helix, and the dimensions come from the standards' tables.
There are two modes: the Configurator with 8 categories and 36 parts (a size and, for 19 parts, a length; a panel shows checks of the pitch, the holes and the grip) and the Fastener handbook with a tightening torque calculator.
A bolt, nut or washer as STL and 3MF
Builds 36 parts in 8 categories
Bolts (7), screws (5), grub screws (4), nuts (7), washers (5), pins (3), circlips (3) and other (a threaded rod and a heat-set insert). Standards: DIN 933, DIN 912, ISO 7380, DIN 934, DIN 985 and more.
Sweeps a true thread on 25 parts
The tooth profile to ISO 68-1 is swept along the helix: crest P/8, root P/4, depth 0.613·P. Internal thread on nuts has a 0.35 mm clearance for printing. Washers, pins and circlips have no thread.
Checks the size and the holes
The tap drill and the ISO 273 clearance hole are in the panel for 15 of the 16 bolts and screws. The pitch is shown for 4 of them, for 4 of the 7 nuts, the threaded rod and the insert. The hex and flange nut warn under 2×D, the threshold for printed plastic.
Gives a handbook and a calculator
Eight sections: threads, ISO 898-1 classes, torque, engagement, holes, choosing a head and a nut, locking, printing. The calculator gives a torque range for M3 to M20 and classes 4.6 to 12.9.
When you need a printable bolt and nut
A fastener has to fit in the drawing, in the calculation and in the printer.
A bolt and nut to print
Print a bolt and a nut in one size. The nut has a 0.35 mm clearance in its thread so it can screw on.
A mock-up in CAD
An STL or 3MF with the standard dimensions goes into the drawing as a model of the fastener.
A lesson on machine elements
A student calculates one bolt in class 8.8 and 10.9 and sees how the proof load and the torque change.
How the bolt tightening torque is calculated
The dimensions come from the standards' tables. The tightening torque is worked out in three steps.
Proof load
A_s is worked out with the coarse pitch P to ISO 261, and F_proof is for the chosen class. Class 8.8 splits at M16: 640 MPa up to it, 660 MPa above it.
Target preload
From 60 to 75% of F_proof. The share comes from the EduFacturing rules core, based on VDI 2230.
Torque
K is 0.20 for a dry thread, 0.18 zinc-plated, 0.14 oiled and 0.10 with PTFE. The result is a range.
| Applies to | Formula | Meaning |
|---|---|---|
| Stress area | A_s = π/4 · (d − 0.9382·P)² | in mm², P is the pitch |
| Proof load | F_proof = A_s · Rp0.2 | in N, with MPa and mm² |
| Target preload | F = (0.60 to 0.75) · F_proof | a range under VDI 2230 |
| Tightening torque | T = K·F·d | in N·m, with d in metres |
| Tap drill | D_hole ≈ D − P | for M8: 8 − 1.25 = 6.75 mm |
Printable threads and torque as a range
The class follows the standard, not the rule of thumb
For 10.9 and 12.9 the calculator takes the published 940 and 1100 MPa for Rp0.2, not the 900 and 1080 that the class-reading rule gives.
A choice of drive
The five machine screws offer slot, Phillips, Pozidriv, Torx or square. Torx follows the ISO 10664 table and the screw size.
Tightening by torque is inexact: between 60 and 90% of the torque goes into friction and the preload differs by about ±25%, so the calculator gives a range. Only the coarse pitch is calculated, and VDI 2230 supplies only the target share: this is not a full joint check.
The material (8 printing materials) changes the colour and the note, not the geometry or the calculation. No STEP file is provided.
Bolt, thread and torque questions
What is the pitch of an M8 bolt?
1.25 mm. The tap drill is D − P, which for M8 is 6.75 mm. The coarse pitches to ISO 261 in the calculator are: M3 0.5, M4 0.7, M5 0.8, M6 1.0, M8 1.25, M10 1.5, M12 1.75, M16 2.0 and M20 2.5 mm.
How to calculate bolt torque?
T = K·F·d, where F is 60 to 75% of A_s·Rp0.2. For M8, class 8.8, dry thread: A_s = 36.6 mm², F_proof = 23.4 kN, preload 14.1 to 17.6 kN, torque 22.5 to 28.1 N·m.
What size wrench for an M10 bolt: 16 or 17 mm?
It is 16 mm under ISO and 17 mm under the old DIN 933. The tool's table uses 16 mm for M10 and 18 mm for M12, where the old DIN has 17 and 19 mm.
How deep should a bolt go into the thread?
The minimum in the rules core is 1×D in steel, 1.5×D in cast iron, 2×D in aluminium and 2.5×D in soft materials such as plastic. For M8 in steel that is 8 mm.
Do 3D printed threads work?
Yes, from M6 up by the handbook. Below M6 an insert or a metal bolt is preferred.
Can I download a nut and bolt STL for free?
Yes. 3 times a day without an account, no limit with a free account. You download STL or 3MF, and no STEP file is provided.
The bolt and nut 3D models is free. Pro opens the rest
Pro costs 15 EUR a month and opens 45 Pro tools.
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Opens without an account 3 times a day. A free account removes the limit.