Spiral Cutterhead for Jet JSL-6J jointer with 30 carbide knives
Woodworkers are upgrading their older planers and jointers by installing spiral cutter heads for the following benefits:
A smoother finish with no tear-out: The slight angle of each knife results in a shear cut, while the spiral cutter head planes the board with a staggered cut, providing a much better outcome than a single straight cut. This eliminates tear-out and produces a glossy surface finish, even on highly figured hardwoods.
Reduced noise: The spiral cutter head enables a few knives to cut in a staggered manner, resulting in greatly reduced noise.
Longer lifespan: The 15x15x2.5mm inserts are made of sintered tungsten carbide, which is much harder than high-speed steel. Each insert has four edges and provides more than 10 times the life use compared to high-speed steel.
Easy knife changes: The knives are precision-ground to a tolerance of +/-0.0004" or +/-0.01mm and are interchangeable. You can change the knife in minutes by loosening the screw, rotating 90° for a new edge, and tightening the insert.
Improved dust extraction: The spiral cutter head creates thinner and shorter chips, making dust extraction easier.
Low cost of use: The spiral cutter head produces a smooth finish, reduces or eliminates sanding work, and doesn't require sharpening. It will pay for itself in a very short time.
The standard kit includes:
A high-tensile alloy steel cutter block
30 installed carbide inserts
Two preinstalled Japan NSK sealed bearings
5 additional carbide inserts
5 screws
1 Torx head T type key


Do I need to replace the original bearings?
If the bearings in your machine are in good condition, they can be reused by carefully removing them with a bearing or pulley puller. However, if the bearings are tightly pressed onto the shaft, removal may cause damage. To minimize this risk, we recommend replacing old bearings with our greased and sealed bearings, designed for long-lasting performance. For a smooth upgrade, we suggest adding the bearings to your shopping cart before completing your purchase.
We provide premium bearings from NSK, SKF, NTN, FAG, Timken. They are renowned for their high quality and performance, designed to provide durability and reliability in various applications
If you add the bearings to your order, we will preinstall them for you when premounting is possible, saving you the hassle of doing it yourself.
Do I need to to Add a Few Boxes of Carbide Inserts
We provide 5 carbide inserts and 5 screws as spare parts. However, many of our customers choose to purchase additional boxes, as the shipping costs for separate purchases can make it less economical.
Do I need a Torque Wrench?
To securely lock the carbide inserts, we recommend applying a torque of 48 to 52 Pound-Inches (or 5.42 to 5.88 Newton-Meters). (Note: 1 Newton-Meter is equal to 8.851 Pound-Inches, and 1 Pound-Inch is approximately 0.113 Newton-Meters.) It is crucial not to apply excessive torque, as this could cause the carbide inserts to crack or explode. On the other hand, using too little torque may result in the inserts not being properly secured, which could lead to cracks, shattering, or uneven height on the cutter block, causing ridges or lines on the board.
If one person is responsible for maintaining the machine, they can typically apply the same torque consistently without a torque wrench. However, when multiple people are involved in machine maintenance, ensuring uniform torque application can be challenging. For consistency and peace of mind, we recommend using a torque wrench.
What kind of steel the cutter block is made of?
The cutter block is constructed using GB/T 40Cr, a structural alloy steel of the same caliber as ASTM grade 5140, AISI 5140, SAE 5140, DIN 41Cr4, BS 41Cr4, JIS SCr440, and EN 41Cr4.The primary components of this steel are as follows: carbon (C) at a range of 0.37-0.44%, silicon (Si) between 0.17-0.37%, manganese (Mn) within 0.50-0.80%, and chromium (Cr) from 0.80-1.10%.
In terms of physical properties, this steel exhibits a tensile strength range of 115-234σb/MPa, a yield strength of 2σ 0.2 ≥/MPa, and an elongation capacity of 65 δ5≥ (%). It also has a HBS range of 123-321 and a HRC rating of 30.
This alloy steel is frequently utilized in low to moderately stressed components for machines, engines, and vehicles.