---
title: "What Are Mirror Screws with Dome Caps Used For?"
description: "Mirror Screws with Dome Caps (Trade series (mirror screw and cap)) are used for fixing into sheet, timber or plastic by forming their own thread as they are…"
url: https://engineeringhardware.com/applications/mirror-screws-dome-caps/
source: Engineering Hardware & Fasteners
---

# What Are Mirror Screws with Dome Caps Used For?

Screws · Trade series (mirror screw and cap) · Application guide

Typical applications, the industries that specify mirror screws with dome caps, and how to choose the right size, material and finish for the joint.

Mirror Screws with Dome Caps are used for fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole. They are manufactured to Trade series (mirror screw and cap), and selection is driven by the screw size, the fit and tolerance the assembly requires, and the service environment.

- **Primary duty:** Fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole
- **Governing standard:** Trade series (mirror screw and cap)
- **Screw size range:** No.8 / 4.2 mm to No.12 / 5.5 mm
- **Category:** Screws

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

![What Are Mirror Screws with Dome Caps Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/09/Mirror-Screws-Dome-Caps.webp)

Mirror Screws with Dome Caps (Trade series (mirror screw and cap)) are specified where the joint requires fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole. The sections below cover the typical end-uses by industry, the size and material decisions for each, assembly practice, and the applications this fastener type is not suited to. Stocked across roughly 8 to 12, they cover general to heavy-duty work.

## Typical Applications for Mirror Screws with Dome Caps

The most common settings where these are specified:

- **Maintenance & repair (MRO):** a stocked size for servicing existing plant where the original fastener spec must be matched.
- **Fabrication & metalwork:** bench and on-site assembly of steel frames, enclosures and weldments.
- **Electronics & enclosures:** mounting PCBs, panels and lids where the drive style and head height matter.
- **Appliances & consumer goods:** high-volume assembly with power tools and consistent seating.
- **Machine guarding & panels:** removable access covers that are opened for service.

Product catalog

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[View all Cap, Dome & Acorn Nuts →](https://engineeringhardware.com/fastener-products/nuts/cap-dome-acorn-nuts/) [Full product catalog](https://engineeringhardware.com/products/)

## How to Specify Mirror Screws with Dome Caps for Your Application

- **Size:** Match the nominal size to the mating thread or hole. This product spans 8–12; check the full table below for the exact dimensions of each size.
- **Drive & head:** Pick the drive (socket, cross, slot) and head style for the tool access and seating surface; a recessed drive resists cam-out under power tools.
- **Environment:** For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- **Standard:** This product is supplied to Trade series (mirror screw and cap). Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

## Installation & Assembly Practice

- Match the driver exactly to the recess (PH ≠ PZ; hex key sizes per ISO 2936) and keep the tool axial — side load is the main cause of stripped drives.
- In tapped holes, engage a thread length of at least 1× the nominal diameter in steel, 2× in aluminum.
- Set power tools to a torque that seats the head without embedding it into the mating surface.

## Common Selection Mistakes with Mirror Screws with Dome Caps

- Under-sizing the drive for the installation torque — a small recess at high torque strips before the screw is seated.
- Using a countersunk head in thin sheet where the countersink removes most of the load-bearing material.
- Specifying stainless in high-strength duty: A2-70 is roughly class 7 steel, not a 10.9 substitute.

## Where Mirror Screws with Dome Caps Are Not the Right Choice

Not for high-preload structural joints (use a property-class bolt and nut), and not in thin sheet where a self-drilling or self-tapping type suits better.

Custom manufacturing · Made to drawing

## Need a mirror screws with dome caps outside the standard range?

Dimensions, material, finish and form are specified from the drawing — a screw outside the standard range is a variation on existing tooling rather than a new design. Made by cold heading or warm forging.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

[Custom screw manufacturing](https://engineeringhardware.com/custom/screws/)[Send a drawing](https://engineeringhardware.com/custom/screws/#rfq)

## Technical Drawing

Dimensioned line drawing of No.8 / 4.2 mm Mirror Screws with Dome Caps to Trade series (mirror screw and cap). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Screw length (mm):** 32
- **Cap thread:** M4
- **Cap diameter (mm):** 12
- **Cap height (mm):** 5.0
- **Cap finish:** Polished chrome
- **Screw drive:** PH2
- **Material:** Steel, nickel plated

## Dimensions & Specifications (Trade series (mirror screw and cap))

| Screw size | Screw length (mm) | Cap thread | Cap diameter (mm) | Cap height (mm) | Cap finish | Screw drive | Material |
| --- | --- | --- | --- | --- | --- | --- | --- |
| No.8 / 4.2 mm | 32 | M4 | 12 | 5.0 | Polished chrome | PH2 | Steel, nickel plated |
| No.8 / 4.2 mm | 38 | M4 | 12 | 5.0 | Polished chrome | PH2 | Steel, nickel plated |
| No.10 / 5 mm | 38 | M4 | 14 | 6.0 | Polished chrome | PH2 | Steel, nickel plated |
| No.10 / 5 mm | 50 | M4 | 14 | 6.0 | Satin nickel | PH2 | A2 stainless |
| No.12 / 5.5 mm | 50 | M5 | 16 | 7.0 | Polished brass | PH2 | Brass |

Inside the plant

## Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift.
2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g.
3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1.
4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227.

## Frequently Asked Questions

### Which industries use Mirror Screws with Dome Caps?

They are commonly specified in maintenance & repair (mro), fabrication & metalwork and electronics & enclosures, among other sectors.

### How do I choose the right size of Mirror Screws with Dome Caps?

Match the nominal size to the mating thread or hole. This product is available from 8 to 12; the full dimension table on this page lists each size.

### What drive type do Mirror Screws with Dome Caps use?

Drive depends on the head style — socket (hex key), cross (Phillips/Pozi) or slot. A recessed drive resists cam-out when driven with power tools; check the product head style on this page.

### What material should Mirror Screws with Dome Caps be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

### Can I get a quote for Mirror Screws with Dome Caps in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.

## Related Pages

Product page: [Mirror Screws with Dome Caps — specifications & sizes](https://engineeringhardware.com/fastener/mirror-screws-dome-caps/)

### Mirror Screws with Dome Caps Specification Guides

### Related Fastener Applications