11-7/8" x 29-1/2" Floor Sanding Belts, 10 PACK

When the job is a gymnasium, a dance hall, a warehouse showroom or a whole-house refinish with big open rooms, crews bring out a 12-inch belt floor sander, and it takes an 11-7/8" x 29-1/2" belt. The wider drum covers more floor per pass and hides lap lines better than an 8 or 10-inch machine, but it also loads the belt harder, which is why we build this size with zirconia alumina on a heavy poly-cotton cloth that will not stretch or tear at the joint under that load.

Zirconia self-sharpens under drum pressure, so it strips old finish and levels boards quickly and runs cool. We stock seven grits from 24 to 120 in packs of 10, enough to run a full sequence on a large floor from a single order.

• Zirconia alumina fractures under load to expose fresh edges: fast stripping, cool running
• Heavy poly-cotton cloth backing built for the drum load of a 12-inch machine
• Seven grits from 24 to 120: first cut through to the final drum pass
• Fits 12-inch belt floor sanders that take an 11-7/8" x 29-1/2" belt; check length in your manual
• 10 belts of one grit per pack; case pricing for commercial flooring crews
• Converted in Anaheim, California; free shipping on orders over $200

Which grit should you run on a 12-inch machine?

The only material in this size is Zirconia, which is the grain we would put on a 12-inch drum regardless: the machine has the weight and power to keep zirconia fracturing, and that is what keeps it cutting through finish instead of riding on top of it. Choose the grit by the floor in front of you.

• 24 grit: the opening cut on a gym floor with thick game-line paint and multiple coats of finish, on painted floors, or on badly cupped boards that need to be brought flat. It removes wood quickly; do not use it on a floor that only needs a refresh.
• 36 grit: the normal first cut on a previously finished hardwood floor in fair condition, and the follow-up to 24.
• 40 grit: a slightly finer opening cut on softwood or thin-finish floors, or the step after 36 when the progression needs to stay tight.
• 60 grit: second cut; levels the floor and removes the coarse scratch. Because this size has no 50 grit, do not go straight from 24 to 60; put 36 or 40 in between.
• 80 grit: third cut, where the scratch pattern from the coarse belts should be gone.
• 100 grit: final drum pass before stain; leaves the tooth stain needs to take evenly.
• 120 grit: final drum pass before a clear finish, especially on maple gym floors and other close-grained species where 100 grit scratches can show through.

A common commercial sequence is 36 → 60 → 80 → 100 for stained floors and 36 → 60 → 80 → 120 for clear-coated maple. If you open with 24, add 40 before 60.

Grit guide for large-floor belt sanding

Does an 11-7/8" x 29-1/2" belt fit your floor sander?

• 12-inch belt floor sanders that specify an 11-7/8" wide belt and a 29-1/2" circumference. Twelve-inch machines are made in more than one belt length, so confirm the length in your manual or on the plate inside the belt guard before you order.
• If your 12-inch machine calls for a 31-1/2" length, use our 11-7/8" x 31-1/2" belt instead; a 29-1/2" belt will not tension on that drum.
• Not for 8-inch or 10-inch machines, which take narrower belts (7-7/8", 8" or 9-7/8" wide).
• Not for portable or bench belt sanders.

To mount: release the tension lever, slide the belt on square, tension it, and roll the drum by hand to see that the belt runs centred before starting the motor. Look inside the belt for a direction arrow first; if there is one, run the belt that way so the joint trails. A belt that is tracking against the flange will fray its edge and can throw itself off under load.

If your machine takes a size we do not stock, we make custom belt sizes to order in about 3 days.

How to get the most out of them

1. Plan the room before you start. On a large floor, work in lanes the length of the room, overlap each lane by about a third of the drum width, and sand the second half of the room from the opposite direction so the lanes meet in the middle.
2. Feather the drum. Lower it only while walking forward and lift it before you stop. A 12-inch drum left down for even a second leaves a wide dish that is hard to buff out.
3. Keep the pace even. The drum sets the depth; your walking speed sets the finish. Slowing down at the end of a lane burns and dishes the boards.
4. Cut on a slight diagonal first when the floor is cupped or has game lines, then run with the grain on every later grit.
5. Step through the grits. On this size that means 36 or 40 between 24 and 60. Jumping leaves coarse scratches that appear the moment finish goes on.
6. Change belts before they glaze. Zirconia that has stopped fracturing burnishes the floor. Shiny boards behind the drum, a slower machine or a change in sound means the belt is finished.
7. Vacuum between every grit. On a big floor, a single coarse particle dragged under the 100 grit belt can leave a scratch across the whole room.
8. Expect faster loading on silicone-contaminated floors (old spray polish, some gym maintenance products). Keep spare coarse belts on hand.
9. Keep belts dry and flat in the truck and the job site, and bring cold belts up to room temperature before mounting so they do not thump on the drum.

Use it for / don't use it for

Use it for

• Stripping game lines, finish and sealer from maple gymnasium and multipurpose floors
• Refinishing large open hardwood floors: halls, showrooms, restaurants, whole-house oak
• Levelling cupped or crowned boards and blending board replacements
• Removing old paint, adhesive and underlayment residue before refinishing
• Flattening new solid hardwood floors before the final buff and finish

Don't use it for

• Engineered or thin-veneer floors at coarse grits; a 12-inch drum can go through the wear layer in one pass
• Machines that call for the 31-1/2" length; the belt will not tension
• Finishing finer than 120; move to the buffer and screens or pads
• Metal, concrete or tile

Specifications

Frequently asked questions

Related products and guides

• All floor sanding belts (8, 10 and 12-inch machines)
• 11-7/8" x 31-1/2" Floor Sanding Belts for longer 12-inch drums
• 9-7/8" x 29-1/2" Floor Sanding Belts for 10-inch machines
• Custom sanding belts made to order in about 3 days