Chipper Knife, 7.25 x 4 x 3/8 in

This replacement chipper knife measures 7.25 x 4 x 3/8 inches and fits brush chippers built around that blade size. Sharp knives feed better, burn less fuel and throw chips farther, so keep a spare set on hand.

Confirming fit

Chipper knives are sold by size, but the size alone does not guarantee a fit. Before ordering a 7.25 x 4 knife, measure your old knife for length, width and thickness, then check the number, size and spacing of the bolt holes and the bevel angle. Compare those with the listing and with your chipper's parts manual.

If your knife has been sharpened many times, it may be narrower than new. Measure the widest unworn edge or check the parts book for the original dimension. When in doubt, contact the chipper maker or a dealer with your model and serial number.

Write down the dimensions of the knives your chipper takes and keep them with the machine's records. When you need a set in a hurry, you will not have to pull a knife just to measure it.

Signs your knives need attention

Dull knives show up fast on the job. The chipper stops self-feeding, brush has to be pushed in, the engine bogs, and chips come out stringy instead of clean. You also burn more fuel and put more strain on bearings and belts.

Inspect knives at a regular interval in the hours your manual recommends, and right after any hit on a rock, nail or piece of steel. Chips, cracks or a rolled edge mean the knife needs to be sharpened or replaced. Check the anvil, or bed knife, at the same time. A worn anvil makes even sharp knives cut poorly.

Feeding practices make a big difference to knife life. Shake dirt and rocks out of brush before it goes in, keep the infeed area clear of gravel, and watch for wire, nails and old fence in yard trees. A single hidden staple can chip a fresh edge.

Changing knives safely

Chipper drums and discs carry a lot of stored energy. Before any knife work, shut the engine off, remove the key, wait for the rotor to stop completely, and lock the rotor per the manufacturer's procedure. Follow your company's lockout steps and the chipper manual. Never reach into the infeed or housing with the rotor turning.

Wear cut-resistant gloves when handling knives. Clean the seat and bolts, replace bolts that are stretched or damaged, and torque them to the value in the manual. Knives are often changed in matched sets so the rotor stays balanced.

Sharpening and spares

Many knives can be resharpened several times by a shop that grinds chipper knives, keeping the original bevel and removing metal evenly across a set. Keep one sharp set in the truck and one at the shop, and you can swap and send out for sharpening without losing a day. Browse other chipper knives if your machine takes a different size.

Track hours between sharpenings for each set. If knives start dulling much faster than usual, check your feeding practices, the anvil gap and whether you are chipping a lot of dirty or sandy material.