This collection brings together our 4 inch flap discs for angle grinders that take a 4 inch disc.
This collection brings together our 4 inch flap discs for angle grinders that take a 4 inch disc. Use them to grind welds, blend and finish metal, stainless steel and wood, with grits from 40 to 120 and a choice of 5/8 inch or 7/8 inch arbor. Buy a single grit in a 10 pack, or an assorted pack to step from coarse to fine.
- 4 inch (100 mm) diameter with a 5/8 inch (16 mm) or 7/8 inch (22 mm) arbor.
- Calcined aluminum oxide discs in 40, 60, 80 or 120 grit, sold in 10 packs.
- Zirconia and ceramic blend assorted pack of 20: six each of 40, 60 and 80 grit, plus two 120 grit.
- Half curved edge zirconia and ceramic discs for fillet welds, corners and contours, 7/8 inch arbor, 5 pack in 40 and 60 grit.
- Conical Type 29 profile on the 120 grit calcined alumina disc.
- All are listed for metal. The calcined alumina and half curved edge discs also list stainless steel, the calcined alumina discs list wood, and the assorted pack lists wood, concrete and stone.
Frequently asked questions
What arbor does a 4 inch grinder flap disc need?
The discs on this page come with a 5/8 inch (16 mm) or 7/8 inch (22 mm) arbor, and the right one is whichever your grinder's spindle and flange take. The calcined alumina and assorted discs are 5/8 inch. The half curved edge fillet weld disc is 7/8 inch. Check the maximum RPM marked on the disc and never exceed it.
Which grit 4 in flap disc should I start with?
Start with 40 grit for heavy stock removal and weld grinding, move to 60 or 80 for blending, and finish with 120 to smooth the surface. The 20-disc assorted pack holds all four grits, so one box covers the whole sequence on a typical job.
Zirconia and ceramic or calcined alumina: which 4 inch flap disc should I buy?
Choose zirconia and ceramic for weld work and rust removal: the half curved edge discs are listed for fillet welds on metal and stainless steel, and the assorted pack for grinding, deburring and rust removal. Choose calcined alumina for general grinding, blending, sanding and finishing on metal, stainless steel and wood. If you work on stainless, keep separate discs for stainless and carbon steel so you do not carry steel particles onto the stainless.
What is a half curved edge flap disc used for?
Its curved edge reaches into fillet welds, inside corners and contours that a flat-faced disc struggles to follow. The one in this collection is 4 inch with a 7/8 inch arbor, in a zirconia and ceramic blend, and comes as a 5 pack with 40 and 60 grit.
Browse all sizes in Flap Discs. To pick a grain, grit and profile, read how to choose a flap disc and Type 27 vs Type 29 flap discs.
Shipping, pickup and returns
- Ships from Whitby, Ontario to Canada and the United States. In-stock orders are dispatched within 1–2 business days.
- Free shipping on orders of $100 CAD or more in Canada and US$100 or more to the US. Otherwise a $20 CAD flat rate in Canada, a $27.50 CAD flat rate to the US, or carrier rates at checkout.
- Local pickup at Unit 2, 1450 Victoria Street East, Whitby, Ontario. Orders are usually ready in about 1 hour during business hours.
- Returns within 14 days of receipt for unused items in original packaging. Refund policy
- Buying in volume? Request a wholesale quote. We reply within 1–2 business days.