7" Silicon Carbide Glass Fabrication Sanding Discs, 50 PACK

Seven-inch discs are the size for hand-held work on glass and stone: a 7" angle grinder or variable-speed polisher with a rubber backing pad and a 7/8" arbor lets you seam long edges, chamfer holes and cutouts, and dress the edges of pieces too large to bring to a bench machine. We make these with silicon carbide bonded to cloth, which cuts glass, granite, quartz, acrylic and concrete cleanly and holds together under a water feed.

The main version is a plain-back disc with a 7/8" centre hole that clamps between a backing pad and lock nut. A PSA (sticky-back) version with no hole is also offered for smooth 7" adhesive plates. Grits run from 50 for chip removal to 800 for pre-polish, and every box holds 50 discs of one grit.

• Silicon carbide grain cuts glass, stone, composites and concrete where aluminum oxide glazes over
• Cloth backing runs wet or dry without tearing at the arbor or delaminating at the rim
• Plain-back 7/8" arbor hole fits standard 7" grinder and polisher backing pads
• PSA no-hole option for smooth adhesive plates on disc sanders and edging heads
• Twelve grits, 50 through 800, so one listing covers shaping to pre-polish
• Box of 50; converted in Anaheim, California; free shipping on orders over $200

Which backing, arbor hole and grit should you choose?

This listing has three choices: Backing (Plain or PSA (Sticky)), Arbor Hole (7/8 Inch or No Hole) and Grit. The backing and hole go together with the machine you own.

• Plain backing, 7/8 Inch arbor hole: the standard configuration. The disc sits on a 7" rubber or phenolic backing pad on an angle grinder or polisher and is clamped by the lock nut through the 7/8" hole. Choose this for hand-held glass, stone and concrete work.
• PSA (Sticky) backing, No Hole: an adhesive-backed disc for a smooth 7" plate on a disc sander, edging head or pneumatic sander. No bolt, no centre gap; peel the liner and press it on.
• Plain backing, No Hole: a plain cloth disc with a solid centre for shops that punch their own hole, cut discs down, or mount with a spray adhesive on a plate.
• PSA (Sticky) backing, 7/8 Inch arbor hole: an adhesive disc with a centre hole, for PSA pads that also carry a centre bolt or locating pin.

Not every grit is stocked in every combination; the variant selector shows what is available. The plain 7/8" disc is offered across the full range, and the PSA no-hole disc has historically been stocked in the fine end for pre-polish work. Call us if you need a combination that is not listed.

Grit by job: 50–60 for chip removal, rough shaping and cutout edges; 80–100 to remove that scratch and true the edge; 120–150 as the intermediate step; 180–220 for a seamed or satin edge; 320–400 for a fine matte; 600–800 for pre-polish before a cork belt or disc charged with cerium oxide.

Grit guide for hand-held glass, stone and concrete edging

What machines does a 7" silicon carbide disc fit?

• 7" angle grinders and variable-speed polishers with a 7" backing pad and a 7/8" arbor. This is the tool most buyers of the plain 7/8" disc own. Use a variable-speed machine on glass and slow it down; a full-speed grinder builds heat fast on a dry edge.
• Wet stone polishers with a centre-water-feed 7" pad, where the 7/8" hole lets water pass through to the face.
• 7" disc sanders, edging heads and pneumatic sanders with a smooth PSA plate, using the No Hole PSA disc.
• Bench disc sanders with a 7" platen in plastics and composite shops, PSA version.

Mounting a plain disc: put the disc on the backing pad, fit the lock nut through the 7/8" hole and snug it by hand plus a quarter turn. Overtightening dishes the pad and buckles the disc. Mounting a PSA disc: wipe the plate, peel the liner, apply from the centre out and press flat; once removed a PSA disc will not re-stick.

These are not hook-and-loop. A hook-and-loop pad needs a PSA conversion pad or a swap to a plain backing pad with a lock nut.

How to get the most out of them

1. Run wet whenever you can. A drip line, a centre-feed pad or a helper with a spray bottle keeps the glass cool, stops micro-chipping and holds silica dust down. Dry work on glass, stone or concrete calls for a fitted respirator and extraction.
2. Slow the tool down. On a variable-speed polisher, run at the low end for glass and fine grits. High speed and a coarse disc on a thin glass edge is how pieces crack.
3. Keep the disc flat and moving. Tilt only a few degrees, use the outer third of the face, and keep the tool travelling along the edge. Dwelling burns and dishes the edge.
4. Light pressure. Silicon carbide cuts by fracturing into fresh points. Leaning on it chips glass and shells the grain off the cloth early.
5. Follow the grit sequence. Never skip more than one step; the next disc only removes the previous scratch, and a hidden coarse scratch shows as a line after polishing.
6. Rinse the work between grits so a coarse particle is not carried onto a fine disc.
7. Check the pad and nut before each grit change. A worn, cupped backing pad rounds your edges and lets the disc flutter.

Use it for / don't use it for

Use it for

• Seaming and edge finishing on large lites, shower doors, storefront glass and glass tabletops in place
• Dressing holes, notches and cutouts in glass, granite, quartz and porcelain
• Granite, marble, quartzite, sandstone and solid-surface edges after diamond shaping
• Concrete countertops, terrazzo, tile and masonry edges
• Acrylic, polycarbonate, fiberglass, gelcoat and composite laminates
• Fine finishing on hardwood where a finer, cleaner scratch than aluminum oxide is wanted

Don't use it for

• Heavy grinding on steel; silicon carbide breaks down quickly on ferrous metal
• Hook-and-loop pads without a conversion pad
• Full-speed dry grinding on glass, which cracks and burns the edge
• Cerium polishing; that job belongs to an ungritted cork belt or disc after the 400–800 grit pass

Specifications

Frequently asked questions

Related products and guides

• All glass fabrication abrasives (belts, cork belts and discs)
• 6" PSA Glass Fabrication Sanding Discs with cork, 50 pack
• 5" PSA Glass Fabrication Sanding Discs with cork, 50 pack
• 1-1/8" x 21" Cork Sanding Belts for cerium polishing
• Custom sanding belts made to order in about 3 days