Positive Rake Carbide Insert Bits, 6-Pack | Fits AMMCO 3850, 4000 & 7000 Brake Lathes | Part #6918-6

Replacement positive rake carbide insert bits sized for AMMCO 3850, 4000, and 7000 series bench brake lathes. The positive rake geometry produces a clean, low-resistance cut for finishing passes on standard rotor materials, minimizing heat buildup and operator fatigue across continuous service. Six-pack format suits lower-volume shops or works as a working spare beside the standard 10-pack stock.

  • Part #: 6918-6
  • Quantity: 6 inserts per pack
  • Rake geometry: Positive
  • Material: Industrial-grade carbide
  • Application: Finish-cut rotor resurfacing on AMMCO bench brake lathes
  • Lathe compatibility: AMMCO 3850, 4000, 7000 series brake lathes
  • Function: Low-force finishing cut with reduced heat and tool load
  • Recommended use: Standard cast iron and composite passenger rotors
Read More

Description

Replacement positive rake carbide insert bits sized for AMMCO 3850, 4000, and 7000 series bench brake lathes. The positive rake geometry produces a clean, low-resistance cut for finishing passes on standard rotor materials, minimizing heat buildup and operator fatigue across continuous service. Six-pack format suits lower-volume shops or works as a working spare beside the standard 10-pack stock.

  • Part #: 6918-6
  • Quantity: 6 inserts per pack
  • Rake geometry: Positive
  • Material: Industrial-grade carbide
  • Application: Finish-cut rotor resurfacing on AMMCO bench brake lathes
  • Lathe compatibility: AMMCO 3850, 4000, 7000 series brake lathes
  • Function: Low-force finishing cut with reduced heat and tool load
  • Recommended use: Standard cast iron and composite passenger rotors

Close

Frequently Asked Questions (FAQs)

What is the actual benefit of a "Positive Rake" angle?
A positive rake angle shears the metal away rather than "plowing" through it. This creates significantly less friction and heat, which prevents the rotor surface from becoming "smeared" or torn. It is the best way to get a factory-quality finish on high-performance rotors.
Why do these bits only have 3 cutting edges?
Because the bit is ground at a specific downward slope to create that sharp shearing edge, it is a single-sided tool. You cannot flip it over because the bottom side does not have the necessary relief angle to cut. You get three precision points on the top face that are optimized for high-speed finishing.
Will these bits help with brake noise (squeal)?
Yes. Many brake squeals are caused by a "directional" finish left by dull or low-quality bits. These positive rake inserts produce a non-directional, mirror-like finish that allows brake pads to bed in perfectly, significantly reducing the chance of noise or "pedal pulsation" after the job is done.
Can I use these on "hard" or high-carbon rotors?
Absolutely. Modern high-carbon rotors are often harder and more brittle. A standard bit might "chatter" or skip across the surface, but the sharp geometry of a positive rake bit slices through the carbon structure cleanly. This makes them the go-to choice for newer European and luxury vehicle rotors.
How do I prevent the tips from chipping?
Because positive rake bits are sharper, they are naturally more delicate. To maximize life, always ensure your silencer bands are tight to stop harmonic vibration. Avoid "slamming" the bit into the rotor; instead, ease into the cut. When used for finishing passes, these bits will stay sharp for a high volume of rotors.
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Positive Rake Carbide Insert Bits, 6-Pack | Fits AMMCO 3850, 4000 & 7000 Brake Lathes | Part #6918-6

    $34.68 $45.87

    Quantity:

    Free Shipping! or Pickup at Pomona Warehouse

      Replacement positive rake carbide insert bits sized for AMMCO 3850, 4000, and 7000 series bench brake lathes. The positive rake geometry produces a clean, low-resistance cut for finishing passes on standard rotor materials, minimizing heat buildup and operator fatigue across continuous service. Six-pack format suits lower-volume shops or works as a working spare beside the standard 10-pack stock.

      • Part #: 6918-6
      • Quantity: 6 inserts per pack
      • Rake geometry: Positive
      • Material: Industrial-grade carbide
      • Application: Finish-cut rotor resurfacing on AMMCO bench brake lathes
      • Lathe compatibility: AMMCO 3850, 4000, 7000 series brake lathes
      • Function: Low-force finishing cut with reduced heat and tool load
      • Recommended use: Standard cast iron and composite passenger rotors
      Read More

      Description

      Replacement positive rake carbide insert bits sized for AMMCO 3850, 4000, and 7000 series bench brake lathes. The positive rake geometry produces a clean, low-resistance cut for finishing passes on standard rotor materials, minimizing heat buildup and operator fatigue across continuous service. Six-pack format suits lower-volume shops or works as a working spare beside the standard 10-pack stock.

      • Part #: 6918-6
      • Quantity: 6 inserts per pack
      • Rake geometry: Positive
      • Material: Industrial-grade carbide
      • Application: Finish-cut rotor resurfacing on AMMCO bench brake lathes
      • Lathe compatibility: AMMCO 3850, 4000, 7000 series brake lathes
      • Function: Low-force finishing cut with reduced heat and tool load
      • Recommended use: Standard cast iron and composite passenger rotors

      Close

      Frequently Asked Questions (FAQs)

      What is the actual benefit of a "Positive Rake" angle?
      A positive rake angle shears the metal away rather than "plowing" through it. This creates significantly less friction and heat, which prevents the rotor surface from becoming "smeared" or torn. It is the best way to get a factory-quality finish on high-performance rotors.
      Why do these bits only have 3 cutting edges?
      Because the bit is ground at a specific downward slope to create that sharp shearing edge, it is a single-sided tool. You cannot flip it over because the bottom side does not have the necessary relief angle to cut. You get three precision points on the top face that are optimized for high-speed finishing.
      Will these bits help with brake noise (squeal)?
      Yes. Many brake squeals are caused by a "directional" finish left by dull or low-quality bits. These positive rake inserts produce a non-directional, mirror-like finish that allows brake pads to bed in perfectly, significantly reducing the chance of noise or "pedal pulsation" after the job is done.
      Can I use these on "hard" or high-carbon rotors?
      Absolutely. Modern high-carbon rotors are often harder and more brittle. A standard bit might "chatter" or skip across the surface, but the sharp geometry of a positive rake bit slices through the carbon structure cleanly. This makes them the go-to choice for newer European and luxury vehicle rotors.
      How do I prevent the tips from chipping?
      Because positive rake bits are sharper, they are naturally more delicate. To maximize life, always ensure your silencer bands are tight to stop harmonic vibration. Avoid "slamming" the bit into the rotor; instead, ease into the cut. When used for finishing passes, these bits will stay sharp for a high volume of rotors.

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