Universal CNC Dragknife (8mm shaft mounted)

Why this design?

• Universal fit – works with any router/spindle
• No brackets or adapters needed
• Cheap & easy to build (unlike commercial dragknives that can cost around 200 €, this design achieves the same functionality at a fraction of the cost)
• Cuts up to 9mm

This dragknife is a fully 3D printable design for CNC machines. All you need to buy are:

• 1 x trapezoidal cutter blade
• 2 × 608 bearings
• 1 × F8-22M-7 thrust bearing
• 1 × DIN9021 M6 washer
• 1 × 8mm calibrated steel rod, 60-100mm length
• 2 x M3x12 + M3 locknut (OK if longer, as long as you're ok with the stick out)

No additional brackets required—fits directly into any standard router or spindle. The design features a precise 3.5mm center shift for accurate cutting. Lightweight, easy to assemble, and the best 3D printed dragknife design available.

There is a support included in the main body, depending on the filament and slicer settings you could need additional support, In that case I would recommend tree supports on the build plate only.

Assembly Instructions:

1. Prepare the thrust bearing:
   Take one half of the thrust bearing and snap it into the “Washer Holder.” The small pin should stick out on top when correctly seated.
2. Install the first 608 bearing:
   Slide a 608 bearing into the slot of the “Main Body” from the side. Push it upwards until it sits just a few millimetres below the upper surface of the slot.
3. Add the thrust bearing assembly:
   Insert the assembled thrust bearing + washer holder from below, facing the previously installed 608 bearing.
4. Place the M6 washer:
   Insert the wide M6 washer on top of the thrust bearing. This acts as a support surface for the spacer.
5. Add spacer and second bearing:
   Drop in the bearing spacer, then insert the second 608 bearing from the top of the main body hole. Push it down until it locks the thrust bearing securely in place.
6. Add 8mm shaft:
   Take the 8mm shaft and press it into the bearings until touching the M6 washer. some lubrication can help and the shaft needs a small chamfer to help the insertion.
7. Check movement:
   Press the assembly together with light pressure and make sure the knife rotates smoothly without binding.
8. Close the slot:
   Push the “Lid” into the slot of the main body until it snaps in place, securing the internal components.
9. Done!
   Your dragknife is ready for clamping the blade with the M3 screws and nuts specified.

Want the Gridifnity bin? You can find it here!

Nice guide on how to generate the Gcode in Vectric Vcarve:

https://info.lagunatools.com/how-to-use-a-drag-knife-with-a-cnc-router

• Included Thrustbearing for better turning under pressure
• Included spacer inbetween ball bearings to allow higher cutting forces and increased rigidity
• Shaft mountedon a 8mm shaft of choosing