Pack of 1 - single 20 x 3 mm N42 neodymium disc magnet on a half-inch reference grid

20mm x 3mm N42 Neodymium Disc Magnets

1
$4.16
$4.16
Skip to product information
Pack of 1 - single 20 x 3 mm N42 neodymium disc magnet on a half-inch reference grid
  • Pack of 1 - single 20 x 3 mm N42 neodymium disc magnet on a half-inch reference grid
  • Overview panel for 20 x 3 mm N42 neodymium disc magnets - 4300 g calculated pull to steel at zero gap, NiCuNi plating, axial magnetisation
  • Stacked rows of 20 x 3 mm N42 neodymium disc magnets shown at real size
  • Infographic - calculated pull reference of 4300 g for a 20 x 3 mm N42 disc magnet on clean flat steel with zero gap
  • Stacked rows of 20 x 3 mm neodymium disc magnets with black spacers between the discs on a dark background
  • Angled view of 20 x 3 mm neodymium disc magnets stacked in parallel rows with black spacers between the discs
  • Rows of 20 x 3 mm neodymium disc magnets separated by black spacers viewed from the side on a dark background
  • Wide block of 20 x 3 mm neodymium disc magnet stacks with black spacers between each disc
  • Long stacked rows of 20 x 3 mm neodymium disc magnets with black spacers on a dark background
  • Magnet safety warning panel: swallowing two or more magnets can cause serious internal injury; keep away from children and medical devices, handle and store with care
  • Infographic - separating small disc magnets safely: slide sideways, keep the stack controlled, mind loose steel and blades
  • Infographic - how diameter and thickness affect disc magnet holding strength and how to read the D x H size format
  • Size chart comparing 2 x 1 mm, 3 x 2 mm and 5 x 3 mm disc magnets on a cutting mat with calculated zero-gap pull of 50 g, 210 g and 650 g
  • Infographic explaining magnet holding force: full pull at direct contact, weaker shear under sideways load, reduced hold across a gap
20mm x 3mm N42 Neodymium Disc Magnets
Hobby Heaven

20mm x 3mm N42 Neodymium Disc Magnets

$4.16
$4.16
Shipping calculated at checkout.
Pack Size
Number of packs

In stock · same-day dispatch before 3pm

  • Store rating 4.9/5 · 2169 reviews
  • UK tracked delivery

DWG · Product Information

PROJ: MAG/D20X3/1 · SHEET 2 / 4

View · Overview

Product overview

At 20 × 3 mm, this N42 neodymium disc sits at the top of the diameter ladder and is almost the size of a 1p coin. The 3 mm thickness keeps the mounting depth manageable, while the 20 mm face spreads the load across a much larger area than the 15 × 3 mm option.

This is the format for transport cases, tool boards, substantial access covers and high-load removable fixings. Its 4,300 g pull is a calculated, zero-gap reference figure rather than a working-load promise, and the sideways shear estimate is approximately 640 g. That combination suits jobs which might otherwise be given a screw or mechanical latch, provided the surrounding material is substantial enough to hold the insert. Black plastic spacers are interleaved through every stack so the discs can be handled one at a time with control. Keep them in place during storage and slide the top magnet sideways with its spacer before removing the spacer from the individual disc.

Use a 20 mm bit and a depth stop to form a 3.2 mm flat-bottomed socket; for a 3D-printed mount, design a 20.1 mm opening. A magnet of this diameter needs a properly supported panel or block, so clamp the work, keep the recess square and confirm the closure geometry before applying adhesive.

Notes · Q & A

Which magnet size should I choose for miniatures?

A 2×1 mm disc suits infantry weapon swaps, while 3×1 mm is a practical step up for arms and small components. Sizes around 3×2 to 5×2 mm work well for basing and larger parts, with 5×3 mm and above better suited to vehicles, large models and army transport. Each listing includes a calculated pull figure in grams so you can compare sizes on the same basis.

What does the N42 magnet grade mean?

The grade describes the magnetic material: at identical dimensions, a higher number generally produces more pull. N52 is typically around 20–25% stronger than N42 at the same size, but increasing the magnet's diameter or thickness usually makes a larger practical difference than changing grade alone. Our range is clearly specified as N42.

How do I keep the polarity consistent?

Before separating the stack, mark one face with a permanent marker and use that mark as your polarity reference. Dry-fit every pair before applying adhesive, and glue the two halves while the magnets are still attracting each other in the intended orientation. Reversing one magnet is one of the most common magnetisation mistakes.

What size hole should I drill for a magnet?

Use a drill matching the magnet diameter; for a designed 3D-printed socket, allow roughly 0.1 mm extra diameter. Make the recess approximately the magnet thickness plus 0.2 mm for adhesive so the face can sit level with the surrounding surface. CA adhesive is suitable for fixing these magnets into plastic, resin or metal parts.

How should neodymium magnets be handled safely?

Swallowing two or more magnets can cause serious internal injury, so keep loose magnets away from children and use them only for adult hobby work. Neodymium magnets are also brittle and may chip if allowed to snap together. Bring them together slowly from the edge rather than letting their flat faces strike each other.

Notes · Logistics

Shipping

Orders placed before 3pm (Mon–Fri) are dispatched the same day. UK delivery is by Royal Mail 24 Tracked. Free UK delivery on orders over £70. International delivery available via Royal Mail International Tracked or courier.

Returns

If you're not happy with your purchase, contact us within 30 days for a full refund or exchange. Items must be unused and in original packaging.

Table · Specification

Technical specifications

Product details
Brand
Hobby Heaven
Product code
MAG/D20X3/1
Type
Accessories
Made in
China
Dimensions & contents
Diameter
20 mm
Thickness
3 mm
Weight per magnet
7.16 g
Magnetic properties
Grade
N42
Pull to steel (calculated, zero gap)
4300 g
Pull to steel
42.17 N
Magnet-to-magnet pull
4300 g
Shear resistance (estimate)
640 g
Magnetisation
Axial
Max working temperature
80 °C
Coating
Nickel-Copper-Nickel (NiCuNi)
Usage & compatibility
Drill bit
20 mm
Hole in 3D prints
20.1 mm
Recess depth
3.2 mm
Size comparison
20 mm — almost exactly a 1p coin (20.3 mm)
Related sizes
Also consider
10mm x 3mm N42 Neodymium Disc Magnets
15mm x 3mm N42 Neodymium Disc Magnets

Product

20mm x 3mm N42 Neodymium Disc Magnets

Code (proj)

MAG/D20X3/1

Brand

Hobby Heaven

Hobby Heaven · By hobbyists, for hobbyists

Sheet 2 / 4

End of sheet

Complete The Job
Brand More from Hobby Heaven