4" x 132" Glass Fabrication Sanding Belt, 12 PACK

The CR Laurence BM132RP upright wet abrasive belt sander is the heavy, reinforced machine large glass shops use for seaming and edging full-size lites, and it runs one 4 x 132 belt at a time. These are the silicon carbide seamer belts for it: converted in Anaheim, California on a Y-weight polyester backing that runs wet or dry, in eleven grits from 50 through 800, for edge sanding, seaming and bevel grinding on glass from a home lapidary setup to a production line.

At 132 inches this is the longest belt in our glass range. More belt means more grain in the water on every revolution, so each grain works less often, the belt runs cooler and it holds its cut longer on big edges. The belts are sized as a drop-in alternative to the CR Laurence PC221 belts sold for this machine, and the polyester cloth is built to outlast typical paper or light-cloth belts. Twelve belts of one grit per pack.

• Made to fit the CR Laurence BM132RP upright wet abrasive belt sander
• Silicon carbide grain, the correct abrasive for glass, mirror, stone and plastics
• Y-weight polyester backing is waterproof; runs flood-wet or dry
• Eleven grits, 50 through 800, seaming through pre-polish
• 132 inch loop runs cooler and holds its cut longer on large lites
• 12 belts per pack; converted in Anaheim, California

Which grit should you run on a BM132RP for seaming and edging?

All variants are silicon carbide; the choice is grit. The BM132RP runs one belt at a time, so most shops keep a coarse belt on for seaming runs and swap to a finer belt for exposed-edge and pre-polish work.

• 50 and 60 grit: seaming raw score-break on thick or laminated lites, removing chips and shells, roughing a bevel, shaping stone and solid surface.
• 80 and 100 grit: the production seaming grit for shower door, storefront, partition and mirror edges that go into a channel or frame.
• 120 grit: refining exposed edges. There is no 150 in this size; step 120 to 180.
• 180 and 220 grit: satin or seamed finish on table tops, shelves and mirrors that will stay matte.
• 320 and 400 grit: smooth matte and the minimum before the cork belt.
• 600 and 800 grit: pre-polish for edges going to cerium oxide.

For lapidary and stone work, 60 to 80 to shape and 220 to 400 before polishing. For acrylic sheet, 120, 220 and 400 then flame or buff.

Grit guide for glass on a 4 x 132 seamer belt

Which machines take a 4 x 132 belt?

• CR Laurence BM132RP Upright Wet Abrasive Belt Sander: a heavy-duty, reinforced upright machine that takes one 4 x 132 belt at a time. This is the machine these belts are made for.
• Other upright or horizontal wet belt sanders built for a 4 inch by 132 inch belt; confirm the length in the manual, as a 4 x 106 machine will not tension this belt.

Check the inside of the belt for a direction arrow before mounting and run it that way. Release tension fully, seat the belt centred on both drums, re-tension, then jog the machine and set tracking before opening the water. A 132 inch loop takes a moment to settle; expect a little drift in the first minute as the belt wets and warms, and re-check tracking after the first few lites. Handle the belt by the loop, not the edge, when mounting so the edge is not creased.

How to get the most out of it

1. Water on before glass on. The polyester backing is waterproof, so run the full flow the BM132RP provides. Water keeps the edge below the temperature where micro-checks form, floats swarf clear and controls silica dust. Dry running is possible with extraction and a fitted respirator.
2. Support the lite and feed light. Large lites should ride on the table or rollers so the belt only sees light, even hand pressure. Pressure chips glass and glazes silicon carbide.
3. Keep the glass moving in steady overlapping passes along the edge; no dwell at corners. Use the full four inch face so the belt wears evenly across its width.
4. Use the roller platen for pencil and radius edges and the flat platen for flat seams and bevels; hold the angle constant along the whole edge.
5. Step one grit at a time on polished work and rinse the lite between belts so coarse grit never rides onto a fine belt.
6. Flush the machine at shift end, change cloudy water, and store spare belts hanging in a large loop or loosely coiled, out of sunlight and away from damp. A 132 inch belt stored folded will take a set at the fold.

Use it for / don't use it for

Use it for

• Seaming and flat edging full-size float, mirror, laminated and pre-temper lites
• Shower door, storefront, partition and table top edges in production
• Pencil edges and bevels on an upright wet sander with roller platen
• Pre-polish before cork and cerium on the same machine
• Stone, quartz, solid-surface and lapidary work on machines of this size

Don't use it for

• Steel or weld grinding; silicon carbide wears fast on ferrous metal
• Dry glass work without extraction and a respirator
• Polishing to clear; that is the job of the 4 x 132 cork belt
• 4 x 106 or any other length machine; belt length must match

Polishing on the BM132RP with the 4 x 132 cork belt

Silicon carbide takes the edge to a fine matte; the clear polish comes from the 4 x 132 cork belt, an ungritted polishing carrier that mounts on the same machine. Finish the silicon carbide sequence at 400 or 800, rinse the glass, mount the cork belt, charge it with cerium oxide slurry and run it wet at moderate speed with light pressure, re-charging as the cut slows. Cork will not remove a scratch coarser than about 400 grit, and it should never run dry against glass with compound caking on it.

Specifications

Frequently asked questions

Related products and guides

• 4" x 132" Cork Sanding Belt, 6 pack, for cerium polishing
• All glass fabrication abrasives (belts, cork belts and discs)
• 4" x 106" Glass Fabrication Sanding Belts for CRL DBS106 and 2300 machines
• 4" x 84" Glass Fabrication Sanding Belts, 9 pack
• Custom sanding belts made to order in about 3 days