MM503 Screw-Top Mandrel – 1.6mm Arbor for Small Radial Discs & Polishing Wheels

£2.99 incl VAT

The standard mandrel for small radial discs and precision finishing wheels

Best for: Stacking radial discs, 19mm 3M Scotch-Brite radial discs, 5/8″ and 7/8″ Dedeco Sunburst discs, felt wheels and small abrasive wheels

The MM503 screw-top mandrel is designed for mounting small unmounted wheels with a 1.6mm centre hole, making it the essential mandrel for many small radial bristle discs and precision polishing consumables.

Available with either a 2.35mm or 3mm shank, it can be used with micromotors, flexible shaft machines, pencil grinders and rotary tools.

Key Benefits:

Correct fit for 1.6mm centre-hole radial discs
Ideal for stacking 3 – 6 discs for a wider working face
Available in 2.35mm and 3mm shank options
Also suitable for selected felts, rubber wheels, diamond wheels and Cratex-style abrasives

View direct-fit radial discs (1.6mm centre hole)

Note for 25mm / 1″ disc users:
Although 25mm radial discs have a 3mm centre hole, the MM503 is commonly used when stacking multiple discs together. The screw head and washers compress the stack securely, allowing users to build a wider polishing face. For single-disc use where maximum stability is required, use the MM304 mandrel.

Moleroda Product Code: MANDRELMM503

Shank Size

Clear

Unit of Sale: EACH

SKU: MANDRELMM503 Categories: Mandrels for Radial Discs, Shank Mounted Mandrels & Holders Tags: 3D Printed & AM Tech, Casting, Jewellery, Mould Tools, Plastics & Non Metals, Precision Engineering, Spindle Mounted

Description
Additional information

A versatile mandrel for precision polishing and radial disc stacking

The MM503 is the standard mandrel for small radial bristle discs and precision finishing wheels, designed specifically for tools requiring a 1.6mm arbor fit. Its slim 1.6mm screw/arbor is designed to pass through the centre hole of smaller abrasive and polishing wheels, allowing them to be securely mounted onto precision rotary tools.

It is especially important for users working with 19mm 3M Scotch-Brite radial bristle discs and 5/8″ or 7/8″ Dedeco Sunburst radial discs, where the correct arbor size is essential for safe, balanced operation.

Using a mandrel with the incorrect arbor size can lead to poor fit, vibration, or unsafe operation – always match the centre hole to the mandrel size.

View all 1.6mm centre hole discs compatible with MM503

Designed for Radial Disc Stacking

Radial bristle discs are often used in multiple layers to create a wider and more effective abrasive face. The MM503 is the preferred mandrel for stacked setups, usually between 3-6 layers, depending on the application.

Stacking helps to:

Increase surface contact
Improve stability during use
Create a wider, more controlled polishing face
Allow users to build custom-width finishing tools

Multi-format stacking compatibility:

19mm / 5/8″ / 7/8″ (1.6mm centre-hole) discs: precise arbor fit for small-format radial discs ideal for building flexible, custom-width polishing heads
25mm / 1″ (3mm centre-hole) discs: suitable for stacking when discs are compressed securely by the screw head and washers

The screw-top design also makes it easy to change grades as you progress through a polishing or deburring sequence.

Looking for a single-disc precision mount?
If you are using one 25mm / 1″ disc and want the most stable, true-running fit, the MM304 mandrel features a matching 3mm arbor for reduced vibration and improved concentricity.

View the MM304 precision mandrel

Beyond Radial Discs:
One Mandrel, Multiple Uses

Although the MM503 is primarily used for small radial bristle discs, it is also compatible with many other small unmounted polishing and finishing wheels with a suitable centre hole.

Typical compatible products include:

Felt wheels, including knife-edge felt wheels
Rubber polishing wheels
22mm diamond wheels
Cratex-style wheels and abrasives

This makes the MM503 a useful general-purpose mandrel for jewellery, dental, engineering and model-making workshops.

Choosing the Correct Shank

2.35mm / 3/32″ Shank

Best for jewellery micromotors, dental handpieces and fine precision rotary tools.

3mm / 1/8″ Shank

Best for Dremel-style tools, pencil grinders, flexible shaft systems and some air tools.

Select the shank size that matches your tool or collet.

Setup Tip

When mounting radial discs, ensure the bristle direction is correctly aligned with the rotation of the tool. Tighten the screw securely before use and run briefly at low speed to check balance before increasing speed.

For users working through multiple grit stages, it can be helpful to keep several MM503 mandrels set up with different grades to reduce changeover time.

Technical Specifications

Mandrel type: Screw-top mandrel
Arbor / screw size: 1.6mm
Available shank sizes: 2.35mm and 3mm
Recommended disc stack: 3 – 6 radial discs, including 25mm formats where appropriate
Material: Hardened steel
Typical use: Stacking small radial discs and mounting selected finishing wheels
Maximum speed: Follow the maximum RPM of the wheel or disc being mounted
Compatible rotary tools: Micromotors, Pencil Grinders & Flexible Shaft Machines