JGAurora A5 E3D drag knife mount [vinyl cutter]

Works well with the vanilla JGAurora A5 hotend, or any of my custom printheads for the JGAurora A5:

• Vanilla JG A5 hotend with Zesty Nimble Remote Direct Extruder V1.2 
• E3D V6/Revo Six Hotend with Zesty Nimble Remote Direct Extruder V1.2
• E3D V6/Revo Six Hotend with The Orbiter v1.5 140g Dual Drive Direct Extruder (not yet published)

Additional required parts:

• Roland Plotter-Cutter compatible drag-knife
• Cutting-pads as protection for the print-bed (e.g. 300x300 mm² sticky pads that hold on to the vinyl)
• 20 mm rubber band or the printed spring
• 2x M3x8 hexagon socket head cap screw
• 2x Ruthex RX-M3x5.7 threaded inserts

Print Settings

Print all models in their provided orientation with 0.4 mm nozzle, 0.2 mm layer height and 3-4 wall lines. PLA should be fine as none of the parts are exposed to elevated temperatures. I've printed mine in extrudr GreenTec Pro silver (bearing-seat-cap_mount and drag-knife_mount) and extrudr PLA NX2 white (counter-ring).

Post Print Instructions

Install the bearing seat cap

Install the threaded inserts in the bearing-seat-cap-mount with a soldering iron or similar tool; and make sure to smooth out the areas making contact with the bearings, using a rounded file or sandpaper:

This part permanently replaces the original aluminium bearing-seat-cap. The groove and threaded inserts allow to fix additional tools like the drag-knife mount to the printhead.

Cutting Operations

Prepare the drag-knife mount

When needed, the drag-knife mount can be attached to the print-head with the two screws:

Here, the counter-ring is already attached with a rubber band (20mm x 1.5mm x 1.5mm) so it can be stored easily before installing the drag-knife:

Instead of the rubber band, the printable spring can be used. However, I personally find the handling less cumbersome with the rubber band, especially since I like to remove the drag-knife for axis homing.

Install the cutting pad

Speaking of cutting pads, I highly recommend using a magnetic bed with a coated spring-steel instead of the pre-installed glass bed. This allows to attach the sticky pad to one of the spring steel plates for quick swapping it with the actual print surface. The bed will not be heated during cutting operations, so there are no special requirements for tmeperature resistant adhesives.

In my case, I used a 12"x12" sticky pad, attached to the spring-steel plate with painter's tape. Aligning the sticky pad to the rear edge of the heated bed and the right marking on the pad with the right edge of the bed is accurate enough so that the markings on the pad can be used to align the vinyl patch before cutting (pad lifted for better visibility):

Install the drag-knife

Before installing the drag-knife, the cut-depth needs to be adjusted to the material that is to be cut, e.g. by following the excellent tutorial Drag Knife, Vinyl Cutter by Ryan.

Before the drag-knife is actually inserted into the mount, make sure to home your printer. Otherwise, the knife will pierce the material or cutting pad.

In order to determine the coordinate offsets, the printhead should now be homed to X=0/Y=0. Then with a tool like OctoPrint or Pronterface, move it to the 0/0 marking on the sticky pad. M114 will then report the current position of the print-head which serves as a offset when preparing the gcode for cutting. The best Z-Height for cuts is where the knife is pushed 1 mm obeove its resting position. Add another 10 mm for the perfect travel-height (without cutting). 

I'm intentionally not providing any specific offsets here since they heavily depend on the actual setup.

Prepare the gcode for cutting

Actually, any software can be used that converts a vector graphic to gcode, ideally allowing for an additional axis offset. Most importantly, it needs to move the Z-axis between the cutting and travel height.

For Inkscape users, the plugin J Tech Photonics Laser Tool provides a simple workflow. Setup the document page size to the accessible cutting area, the plugin “maschine origin” to “bottom-left” and the “Bed Y Length” to the document height plus the measured y-offset. The settings “Tool Power Command” and “Tool Off Command” can be used to specify g-code that move the z-axis to cutting ("power") or travel ("off") height, respectively.

For precisely cut forms however, a gcode-post-processor is required, that adds extra movements to reorient the knife on each turn. Otherwise, the resulting shape will deviate from the original (Italic letters with 12 mm height):

To get acquainted with the workflow and the required settings, I highly recommend to perform at least one dry-run without installing the knife to avoid damaging any of the involved hardware.

Suitable Print Heads

The drag-knife can be mounted to a number of JG-Aurora A5 print heads (and probably others):

• Vanilla JG A5 hotend (here with JGAurora A5 3D-Touch sidemount):

• Vanilla JG A5 hotend with Zesty Nimble Remote Direct Extruder V1.2:

• JG Aurora A5 printhead with E3D V6/Revo Six Hotend and either bowden or Zesty Nimble extruder

• Coming soon: E3D V6/Revo Six Hotend with The Orbiter v1.5 140g Dual Drive Direct Extruder