This is the wide-kerf 12 inch MK-505, and it exists for cuts that have to hold something. A .250 inch kerf is sized for joint sealant and backer rod, for dropping conduit or a dowel into a slab, and for repair cutouts that need a square shoulder for the patch to key into. Pairing that width with MK's premium bond and 12 mm segment means the blade can take the extra load a quarter-inch kerf puts on it, run after run, on a saw in the 8 to 20 hp range.
Built for
- Expansion and control joints cut to accept sealant and backer rod
- Slab cutouts where conduit, dowels or a repair key drop into the kerf
- Production joint sawing where a standard blade would not survive the width
- High-horsepower walk-behind saws running daily
- Long straight cuts where a thin blade tends to wander
Specifications
- Model: MK Diamond MK-505, Premium grade for cured concrete
- Diameter: 12 inch (305 mm)
- Kerf (blade width): .250 inch
- Arbor: 1 inch
- Segment height: 12 mm
- Rim type: segmented, laser welded
- Cutting method: wet cutting only
- Published horsepower range for the MK-505 line: 8 to 20 hp
- MK Diamond part number: 129031
How to choose between grades
MK publishes its cured-concrete contractor blades in tiers that differ on segment height and the horsepower they are bonded for, not on cosmetics. The MK-500 standard grade carries a 10 mm segment and is rated 5 to 12 hp. The MK-505 premium grade carries a 12 mm segment and is rated 8 to 20 hp. Taller segment means more diamond to consume before the blade is spent, and the higher horsepower rating means the bond is built to survive the feed rate a bigger saw can push. Putting a premium blade on an underpowered saw will not make it cut faster, and putting a standard blade on a 20 hp saw will simply wear it out sooner. Match the blade to the saw first, then to the material.
Safe operation
This is a wet-cutting blade and it must be run with a continuous water feed. Running a wet blade dry is the single most common cause of segment loss, core warping and a scrapped blade, and it also puts respirable crystalline silica into the air. Water does two jobs at once: it carries heat out of the core and it knocks the dust down at the cut. Confirm your saw's arbor matches the blade before mounting, seat the blade flat against the flange, and never exceed the maximum operating speed stamped on the blade.
Frequently asked questions
Why does a .250 kerf need a premium blade?
Because the wider kerf doubles the material the blade removes per linear foot, and that load has to go somewhere. A premium bond and a taller 12 mm segment give the blade the mass and the diamond depth to carry that load repeatedly instead of rounding over.
How much slower will it cut than a .125?
Expect a noticeably slower feed at the same horsepower, because you are removing twice the concrete. That is normal and you should not force it. Let the saw hold its speed and let the diamonds work.
Do I need a 20 hp saw for this?
No, but stay inside MK's published range of 8 to 20 hp for the MK-505 line. A .250 kerf sits at the demanding end, so a saw near the bottom of the range will simply cut slower.
Will slurry pack in a wide kerf?
It can if the water is thin. Run generous, continuous water on both sides of the blade so the slurry flushes out of the cut rather than grinding in it.
Discount Cleaning Products is an authorized MK Diamond dealer. We stock the contractor blade lines rather than drop-shipping whatever a marketplace listing happens to carry, so the part number you order is the part number MK prints in its own catalog. Our US-based team can confirm arbor size, kerf and horsepower fit against your saw before you buy, and can help you match bond hardness to the aggregate you are actually cutting.
