Fibre Discs, Belts or Wet and Dry? Abrasives for Welds and Paint

Grinding a weld flush, flatting filler for primer and stripping a rusty chassis each need a different abrasive. Use the wrong one and the job drags on or the finish suffers. Match the abrasive to the job and the tool, then pick the grit for the stage.

PartsForMachines offers 1,571 Abracs, Draper, Sealey, Osborn, SIP and PCL products in its sanding and finishing range.

Fibre Disc or Flap Disc: Which Is Better for Grinding Welds?

Use a coarse fibre disc to take a weld bead down quickly, or a flap disc if you want to remove and blend it in one step. A fibre disc is a layer of grit on a fibre backing, run on an angle grinder with a backing pad behind it. The pad spreads the pressure, cuts down chatter and lets the disc follow curved or uneven work. The 36 and 50 grit discs are coarse grades for fast stock removal, such as the FBD11536 36-grit fibre disc, made for grinding back weld seams and stripping paint from metal and wood.

What Grit Should Filler and Primer Be Before Paint?

Shape filler with a coarse grit such as 80, refine it with 120 or 180, and finish at around 220 before you prime. The 120 and 180 grades are made for shaping filler and for taking off old paint and primer.

Once the primer is on, flat it with 240 to 800 grit, the range made for primers, sealers and the final sand before painting. The WD2328400 400-grit wet and dry paper sits in the middle of that range. Keep 1000 grit for after the topcoat, before buffing.

Which Linisher Belt Size and Grit Do I Need?

Match the belt size to your machine first, then pick a coarse grit for heavy removal or 80 for flattening and deburring. The SIP 6in linisher takes 2000 x 150mm belts and the 3in model 2000 x 75mm, while 50 x 686mm belts suit the BG150BS bench grinder and belt sander and other makes.

P36 is a coarse grade for heavy removal and taking off burrs, P60 suits aggressive stock removal and edge preparation, and P80 suits flattening, sharpening and deburring. Aluminium oxide is the cost-effective general choice. SIP rates its zirconium belts as more durable and heat resistant, and they suit stainless as well as mild steel and aluminium. The 08678 P80 zirconium linisher belt fits the 6in machine.

How Do I Strip Rust and Paint Off a Chassis With a Grinder?

Fit a wire cup brush: twist-knot for heavy rust and scale, crimped for general rust removal and paint stripping. Twisted knots give a more aggressive cleaning action, while crimped wire adds rigidity.

Check the speed first: the brush must be rated at or above your grinder's top speed. Smaller cup brushes are usually rated higher, for example 12,500rpm for the TKCB651 65mm twist-knot cup brush against 8,500rpm for 100mm sizes. Wires can break off in use, so wear goggles or a full face shield.

What Should I Check Before I Buy?

• The job: taking welds down, shaping filler, flatting primer, linishing or stripping rust.
• The fit: disc diameter and backing-pad thread, sander pad size or belt width and length, and a brush speed rating at least equal to your tool's.
• The grit for the stage: coarse for removal, finer for shaping, 240 to 800 for primer.
• The grain or wire for the material: zirconium or ceramic for stainless, and stainless wire on stainless and aluminium.
• A pack size you will use: many discs and sheets come in packs of 25.

Not sure which abrasive suits the job? Browse the sanding and finishing range or contact the PartsForMachines team by WhatsApp, telephone or email with your tool, the material and the finish you need.

Pack sizes, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

Which backing pad do fibre discs need?

One that matches the disc diameter and your grinder's spindle thread. The pads for 115, 125 and 178mm fibre discs have an M14 thread, such as the PHBP11514 115mm backing pad. On a smaller grinder, check the spindle thread before you order.

Are ceramic fibre discs worth it for stainless?

Often, yes. Abracs rates its ceramic fibre discs for fast cutting and long life on stainless and hard-to-grind alloys, as the grain keeps exposing fresh edges. For everyday steel work, discs with aluminium and zirconia oxide grain handle weld seams and paint removal.

Should body filler be wet or dry sanded?

Dry. Polyester filler takes up moisture, and wet sanding it can cause defects in the paint later. Save wet sanding for the primer and paint stages, where wet and dry paper used with water clogs less.

Does dry sanding primer clog the paper?

It can. Wet and dry paper used wet reduces clogging and gives a more even surface. If you sand dry with a sander, sheets with dust-extraction holes and an anti-static finish stay clearer for longer.

Which hook-and-loop pad fits my DA sander?

One with the same diameter, thread and hole pattern as the old pad, with discs to match. For example, the AK290 is a 150mm dust-free pad with a 5/16in UNF thread that takes 150mm hook-and-loop papers.

My machine takes an odd belt size. Can I still get one?

Often, yes. Sizes include 6 x 610mm file belts, 50 x 686mm bench sander belts and 2000 x 150mm linisher belts. Measure the old belt's width and length, or check the machine's manual, and send our team the size if you can't find it.

How should I store sanding belts and discs?

Somewhere dry and frost-free, away from damp, direct sunlight and big temperature swings. The same conditions apply to coated abrasives, such as belts and sheets, and to bonded discs.

Can quick-change sanding discs fit an angle grinder?

Not directly. Quick-change backing pads have a 6mm spindle, like the 50mm and 75mm Quick-Lock pads, or a 1/4in UNC thread for mini air sanders, not an M14 thread. The small zirconium Quick-Lock discs suit stainless and hard-to-reach places.

Do I need a stainless steel wire brush for stainless?

Yes. Stainless wire avoids leaving iron on the surface, which matters on stainless, aluminium and other non-ferrous work. For angle grinders, knotted stainless cup brushes come in 65, 80 and 100mm sizes with an M14 thread.

Can I strip rust with a wire brush in a drill?

Yes, for small jobs. Drill cup brushes have a 6mm round shaft or a 6.35mm hex shank, and the SCB crimped cup brushes are rated to 4,500rpm, so check that your drill's top speed does not go above that.