Vinyl knife attachment for Roland style knife holder, attaches to 80mm spindle.
Note that the spindle itself is not used; the knife holder has its own integral bearings so the attachment holds it offset from the spindle.
The knife holder can slide inside the boss, held by the spring. This allows the knife pressure to be adjusted by the changing depth of cut.
Bill of materials
- Knife boss, 3D printed
- Bracket, CNC cut from 8-10mm acrylic or aluminium
- M3 x 15mm machine screws + nuts x 3
- M4 x 20mm machine screw + nut
- 8mm x 25mm x 0.5mm compression spring, light
- Roland style knife holder and knife, with lock ring that is screw adjustable - see photo. These are readily available on ebay.
Knife boss:
- Print from ABS, PLA or similar
- If needed, drill or ream the core to 11.5mm to allow the knife holder to slide smoothly through
Bracket:
- This can be cut with 1/8" / 3.175mm or smaller tool
- After cutting, drill the 4mm clamping screw hole through to the nut trap. I use a square block and a clamp on my drill press, placing some packing in the slot to keep it parallel
Assembly:
- Remove the lock ring and upper nut from the knife holder. Drop the lock ring into the slot in the boss, insert the holder from the nose end, then screw the upper nut. Make sure the knife holder slides smoothly inside the boss.
- Insert the spring between the knife holder and the bracket.
- Press the M3 nuts into the flange of the boss
- Use the M3 screws to attach the boss to the bracket.
Usage:
- I use Artcam to run my CNC. I simply created a tool for the knife with a zero (well actually 1 rpm) speed for the spindle which leaves it turned off.
- I use my 'A4 mini vacuum table' (see my Things) with a thin milled (~1.5mm) piece of MDF on top. This is milled both sides to allow maximum air to flow through it.
- I have found a depth of cut around 0.2mm to be about right; this cuts the vinyl but not the backing.
- I have successfully cut at 5000 mm/min with 1500 mm/m plunge speed. Could probably cut faster!
loska
