Magnets for 3D Printing

Disc magnets for 3D prints

Choose from the stock sizes below. Sizes are diameter x thickness in millimetres, and each product page lists the grade, pull force and tolerance.

Popular sizes

Larger and screw-fixing

Small and thin

Need a different size or shape?

If you can't see the grade or size you require, get in touch. We may have it off the shelf, and if not, we can quote to have it made.

Which size to choose

Magnets turn up in almost every kind of print: electronics cases and box lids, tool holders, Gridfinity and workshop storage, modular models, cosplay props and helmets, tabletop miniatures and terrain, fridge magnets and fidget toys. If you're printing someone else's model, check its description first, because the designer drew the pocket for one particular magnet.

If you're designing your own, size the magnet to the part:

• Small, light parts such as bins, boxes and small lids: 6x2mm and 6x3mm discs are the usual choice.
• Bigger parts that are handled a lot such as box lids, cases and tool holders: 8x3mm and 10x3mm give a firmer hold.
• Heavy or wall-mounted parts: go up a size, use more than one magnet, or choose a countersunk magnet you can screw in.
• Miniatures and very small parts: the smallest discs, so the magnet hides inside a base or a joint.

To compare the pull of different sizes, use the MagNet™ Pull Force Calculator.

Sizing the hole

Magnets can measure slightly under their stated size. In a pocket drawn for 3mm, a thin magnet sits low and the joint feels weak; in a press-fit hole it can fall straight out. Each of our product pages lists the tolerance, so you know what you're designing for.

Let the software size it for you with our 3D Print Magnet Designer. Upload your model and it measures the magnet hole, resizes it for a stronger magnet, or adds a new hole sized for your printer. If you'd rather work it out by hand:

• Printed holes usually come out slightly smaller than drawn. The amount depends on your printer, material and slicer settings.
• For a glued fit, draw the hole a little larger than the magnet so there's room for adhesive.
• For a press fit, the hole needs to be very close to the magnet's size so the plastic grips it.
• A simple way to find your numbers is to print a small test block with a row of holes in small steps, then try the magnet in each one. Do it once per printer and material, and keep the result.
• Make the pocket deep enough for the magnet to sit flush or just below the surface. A magnet that stands proud gets knocked out.

Press-fit, glue or print over

Why magnets come loose

When a magnet comes loose, it's nearly always the joint, not the magnet.

• The wrong glue. Superglue is brittle once set and can crack under stress. Use a two-part epoxy for parts that are handled or dropped.
• A greasy or dusty surface. Wipe the magnet and the hole with isopropyl alcohol before gluing.
• An oversized hole. Glue won't make up for a loose fit. Use your test block to get the hole right.
• A magnet that sits proud. Recess it flush or slightly below the surface.
• Two strong magnets meeting. The pull between them can drag one out of its hole. If you face this issue, use a smaller magnet on one side, or pair the magnet with a steel disc or washer.

Don't sand or scuff the magnet to give the glue more grip. The coating protects neodymium from corrosion, and if it's chipped or cracked the magnet can rust. Some coatings are more suitable than others, depending on where the part will be used: a damp shed or outdoor part needs more protection than one kept indoors. Our guide to magnet coatings compares each coating and what it suits.

Getting polarity right

Two parts that should snap together will push apart if one magnet goes in the wrong way round, and once it's glued it's hard to fix.

• Stack your magnets into a single column before you fit anything. While they're stacked, every magnet faces the same way, so every top face is the same pole.
• Mark that top face with a dot of paint or permanent marker while they're still stacked.
• Fit the marked faces facing out on one part and facing in on the mating part. Test the pair dry before any glue goes in.

If a magnet does go in backwards, don't try to drill it out. Neodymium is brittle and can chip or break. It's usually easier to reprint the part.

Grade and heat

A higher grade gives more pull from the same size, which helps when you can't make the magnet any bigger. Each product page lists its grade and maximum working temperature. If a part will sit in a hot enclosure, near a heated bed or in a car in summer, see our high temperature magnets and the neodymium magnet grades guide.

Pull force figures are for a straight pull on thick bare steel with no gap. In a print, any plastic between the magnet and what it holds acts as a gap, and pull falls quickly as that gap grows, so keep the layer over the magnet as thin as you can. To compare grades and sizes, and see how much pull is left through a gap, use the MagNet™ Pull Force Calculator.

Safety

Neodymium magnets are not toys. Keep them away from children: swallowing even small magnets can cause life-threatening internal injuries. Keep them away from pacemakers and other implanted medical devices. Read our magnet safety guide before you start.

Frequently asked questions

What size magnets do most 3D printing models use?

6x2 and 6x3mm discs are among the most popular, with 8x3 and 10x3mm for bigger parts. Check the model's description, because the designer drew the pocket for one particular magnet.

How big should I make the hole for a 6x3mm magnet?

It depends on your printer and material, because printed holes usually come out slightly small. Print a test block with holes in small steps around 6mm and use the one that gives the fit you want: snug for a press fit, slightly looser for glue. Or upload your model to the 3D Print Magnet Designer.

What's the best glue for magnets in 3D prints?

A two-part epoxy. It fills small gaps and stands up well to impact, while superglue cures brittle and can crack. Clean the magnet and the hole with isopropyl alcohol first, and let the epoxy cure fully.

How do I keep the polarity the same on every magnet?

Stack the magnets in a column, mark the top face of each, then fit them all with the marked face the same way. Test the two parts together before you glue.

Should I sand magnets so the glue sticks better?

No. Sanding damages the coating that protects the magnet from corrosion. Get the hole size right, use epoxy, or print over the magnet instead.

Does a higher grade magnet help?

A higher grade gives more pull from the same size, which helps when space is tight. If the joint needs more hold and you have room, going up a size also works.