How to Mate Parts with Threads in SOLIDWORKS Assemblies

Contents

SOLIDWORKS assemblies offer many mate types, but one of the most useful for threaded motion is the Screw mate (found under Mechanical Mates). A screw mate couples rotation to linear travel along a shared axis—so when you rotate a bolt, it advances into (or out of) a nut just like a real fastener.

This article shows a practical workflow for mating two M10×1.0 threaded components, then expands into best practices, thread modeling tips, and troubleshooting.

What a Screw Mate Actually Does (and What It Doesn’t)

A screw mate:

keeps two components concentric (same axis), and
adds a pitch/lead relationship between rotation and translation.

Important: A screw mate is a motion relationship, not a detailed thread-contact simulation. In most projects you do not need fully modeled helical thread geometry for the mate to work—you mainly need a reliable axis (or cylindrical faces) and the correct screw advance value.

Step-by-Step: Constraining Two M10×1.0 Fasteners

The steps below mirror a real-world workflow when threads are modeled and selections can be tricky.

Fully constrain one of the two items. In this case, the nut is constrained to the origin (or otherwise fixed/fully mated so it cannot drift).
Turn temporary axis visibility on. Use the Hide/Show Items button in the graphics area and choose View Temporary Axes (or use the equivalent menu option in your SOLIDWORKS version).
Align the bolt and nut axes. Create a new mate and select the axis of the nut and the axis of the bolt. Apply a concentric-style alignment (often done by selecting axes or cylindrical references). Use Mate Alignment if you need to flip the orientation.
Create a section view through the nut/bolt. A section view makes it much easier to pick the correct cylindrical faces (especially when modeled threads create many small faces and edges).
Create the Screw mate (Mechanical Mates > Screw). Select the cylindrical faces (or appropriate reference entities) that represent the thread’s working diameter. Set the screw advance value to match the thread:
- For M10×1.0, the thread advances 1.0 mm per revolution (single-start thread).
- If the motion direction is backward, use the mate’s Reverse option (or flip alignment) so tightening moves the bolt in the expected direction.

Once mating is complete, return to the full view of the model. You can tighten/loosen the bolt by selecting it and rotating it within its allowed degrees of freedom—the screw mate should convert that rotation into realistic linear travel.

Understanding the Screw Mate Settings

Distance per Revolution: Use the Correct Value

The key input in a screw mate is typically distance per revolution—how far the component translates for one full turn.

Metric threads: for common single-start fasteners, distance/rev = pitch. Example: M10×1.0 → 1.0 mm per revolution.
Inch threads (TPI): distance/rev is the inverse of TPI (e.g., 20 TPI → 1/20 in per revolution).
Multi-start threads or lead screws: distance/rev should be the lead (pitch × number of starts), not the pitch.

Reverse and Mate Alignment

If rotation drives translation the wrong way (tightening appears to “unscrew”), you generally fix it by:

using the mate’s Reverse option, or
flipping mate alignment (aligned/anti-aligned) depending on how your references were selected.

Modeling Threads in SOLIDWORKS: Cosmetic vs. Physical Threads

Thread geometry can add realism, but it also adds file size and rebuild/solve cost—especially in assemblies with lots of hardware.

Cosmetic Threads (Recommended for Most Assemblies)

Cosmetic threads are lightweight and ideal for drawings, callouts, and general design communication. They visually represent threads without building full helical geometry, which keeps assemblies fast and stable.

Physical (Modeled) Threads (Use Sparingly)

Modeled threads can be appropriate for:

3D printing where threads must be physically present,
close-up renders, or
interference checks that rely on actual thread geometry.

If you do model threads, keep an eye on performance and consider limiting modeled threads to only the components that truly require them.

Selection Tips (Especially When Threads Are Fully Modeled)

Modeled threads often create many small faces, making it easy to select the wrong geometry. These techniques help:

Use a section view (as in the workflow above) to expose the intended cylindrical surfaces.
Temporarily hide obstructing faces while selecting mate references (SOLIDWORKS provides shortcuts to help with obscured selections).
Mate to robust references when possible: axes, reference geometry, or clean cylindrical faces tend to be more stable than tiny thread facets.

How to Test (and Trust) a Screw Mate

Quick Functional Test

Open the assembly containing the screw mate.
Click the bolt (or nut) component and rotate it (drag-rotate or use the assembly move/rotate tools).
Confirm the paired component translates smoothly along the axis and that the direction matches tightening/loosening expectations.

Common Problems and Fixes

The bolt spins but doesn’t move axially: the screw mate may not be applied to the correct references, or the component may still be free to rotate without the screw relationship driving translation.
Motion is backward: flip alignment or use the mate’s Reverse control.
Assembly becomes over-defined: screw mates already enforce concentric behavior plus a motion relationship. Remove redundant mates that duplicate the same constraints.
I can’t select the right face: use section view and obscured-selection tricks; avoid mating to tiny thread facets whenever possible.

Conclusion

The Screw mate is one of the cleanest ways to simulate threaded motion in SOLIDWORKS assemblies. When you set the correct distance-per-revolution value (and choose stable reference geometry), you get a realistic tighten/loosen behavior without needing heavy thread geometry everywhere. Use cosmetic threads for speed, model threads only when you need the actual helical form, and always sanity-check the direction and travel before building more mates around it.