For a Kossel 2020 Delta and other similar Delta 3D printers:
- Adds a glass bed for more convenient printing
- Adds 6 point manual bed leveling.
- Eliminates the need for auto bed leveling inductor which reduces print head weight.
- Allows one-time bed leveling, although minor adjustments can be made even during printing.
- Includes hot end mount without inductor holder and captive hex nuts for easier mounting
- Allows print head calibration without flashing the firmware
- includes carriage with adjusting screw for easier calibration
Requires making a new bed mounting board from MDF or other suitable material. The aluminum heated bed gets drilled and tapped so that mounting screws can be attached to the bottom of the bed. This eliminates the screw heads from the top of the bed, allowing a borosilicate glass plate to be used on top of the aluminum plate. Springs are used in conjunction with printed thumbwheels to provide 6 leveling points for the bed for making fine adjustments even during printing.
These print settings are not critical. There are just two parts to print for the bed mounting, a thumbwheel and a spacer. You will need 6 of each. Print the parts before disassembling your printer.
I have included a modified hot end mount that does not have the holder for the auto leveling inductor. It features captive hex nuts that makes mounting and removing the hot end much easier.
I have also included a modified carriage that features an adjusting screw for easier calibration.
See my improved sliders and carriages for delta printers here
- jig saw, table saw, sliding miter saw or other means of cutting the MDF.
- drill press.
- 3.5 mm drill bit
- 2.5 mm drill bit (optional)
- 4 mm drill bit
- 4 mm tap
- 3 mm tap (optional)
- 1/2" thick MDF large enough to cover the base of the printer
- M4 x 45 mm pan head screws (6)
- M4 hex nuts (6)
- M4 hex keeper nuts (6) or M4 hex nuts and lock washers (6 each)
- Compression spring - 1 1/8 x 1/4 x .035 (6) - Ace Hardware #145
- M3 x 20 mm pan head screws (6)
- M3 twist lock T-nuts (6)
- M3 washers (6)
- Round Borosilicate Glass - 220 mm diameter x 3 mm thick
- 3/4" Binder Clips (3)
MAKE THE BASE BOARD
Place the printer on top of the MDF board and trace the outline of the triangle. Don't worry too much about the corners as these will get cut off. Draw guide lines 10 mm inside the traced line for the mounting screws. Cut out the triangle using the saw of your choice. Cut off the corners of the triangle so that the board fits the base of your printer without interfering with the belts.
DRILL THE MOUNTING HOLES FOR THE HEATED BED
Center the aluminum heated bed on the triangle and carefully mark the 6 mounting holes. A self-centering vix bit is particularly useful. If you have marked accurately, you can drill the holes using a 4 mm bit. If your marking is inaccurate, it is okay to drill these holes slightly oversized, but you may need an additional washer on the underside of the board during assembly.
DRILL THE MOUNTING HOLES FOR THE BASE BOARD
Using the 10 mm guide line, drill 2 holes on each edge for mounting the board on the 2020 rails. Spacing is not critical here, approximately 1 inch from the end is what I used. I drilled these to 3.5 mm to give some additional tolerance when mounting.
DRILL THE MOUNTING HOLES FOR THE CONTROLLER BOARD AND HEATED BED WIRING
Mark and drill holes for mounting the controller boards. I drilled 2.5mm holes and tapped them to 3 mm. You could also drill them to 3mm and use a nut. Another option is to mount the controller board using nylon zip ties. This requires 2 small holes at each mounting point to loop the zip tie through.
Drill a larger hole at the point that you want to bring down your heated bed wiring.
You can paint the MDF board with shellac based primer
The base board with all the holes drilled. The large hole is for the wires
DRILL AND TAP THE HOLES IN THE ALUMINUM HEATED PLATE
Using a drill press to keep the holes vertical, enlarge the existing holes to 3.5mm. Then cut threads in the holes using a 4mm tap.
The aluminum heated bed is drilled and tapped to accept M4 screws
ASSEMBLE THE BED MOUNTING HARDWARE
The hardware is installed in the order of the photo below. The M4 x 45mm screw and spring are inserted first from below the base board. If the spring is sliding into your oversized mounting hole, use an M4 washer between the board and the spring. Above the board, add the spacer, the thumbwheel with the hex head opening facing up and the hex nut. Lastly add the keeper nut or hex nut and lock washer. Do this for each of the 6 mounting holes.
The bed mounting hardware in the order of assembly
The adjustable bed mounting assembly
MOUNT THE CONTROLLER BOARD
Attach the controller board to the bottom of the base board.
The mounted controller board
MOUNT THE HEATED BED TO THE BASE BOARD
After routing the heater and thermistor wires through the large wiring hole, place the aluminum plate on top of the mounting hardware so that the screws line up with the mounting holes. Thread the screws into the aluminum plate until the screws are flush with or just below the top surface of the plate. Tighten the keeper nuts (or lock washer and hex nut) against the bottom of the aluminum plate to lock the screws to the plate. This will keep the screws from turning when adjusting the thumb screws.
Mounting screws locked to the aluminum plate with the keeper nuts.
MOUNT THE BASE BOARD ONTO THE PRINTER
Using the M3 x 20 mm screws and the M3 twist lock nuts, mount the base board onto the printer's rails. Use a washer to keep the screw heads from sliding into the oversized holes and to keep the 20mm screws from bottoming out in the rails. It takes some determination to get all 6 twist lock nuts lined up and secured. If necessary, drill the holes slightly larger.
The M3 twist lock nuts are 10mm from the edge so that they are centered on the 20mm rails.
ATTACH THE GLASS TO THE PRINT BED
Use 3 or 4 3/4" binder clips to hold the glass onto the print bed. A mist of hair spray on the glass will help the prints adhere better. Adjust the thumbwheels so that none of them are loose. The thumb wheels can be used to make minor leveling adjustments to the print bed, even during printing. Be careful to make small adjustments as it is possible to actually bend the aluminum plate
The finished modification.
Design Goals & Motivation
Bed leveling is a particular challenge on a delta printer. I wanted to find an alternative to inductive auto bed leveling as it was difficult to configure, relatively ineffective and added unnecessary weight to the print head assembly. The auto leveling has to execute before every print as the leveling values are cleared with a home command.
Without the inductive auto bed leveling which requires a metallic surface to function, there was no reason not to add glass to the print bed. The glass print bed eliminates the need for the blue painters tape which is much more of a hassle to use than hair spray. In order to add a glass plate to the aluminum heated bed, I had to get rid of the screw heads, which meant either using flat head screws and counter sinking them into the aluminum bed, or tapping threads into the holes and attaching the screws from the bottom. It would certainly be possible to modify this design to work with countersunk flat head screws if you didn't have a 4mm tap.
I liked the bed leveling adjustment that is available on the Prusa I3 and similar XYZ printers, but these have the adjustment knobs under the bed mounts and springs supporting the bed. This is difficult to duplicate on a delta printer where access to the underside of the bed mounts is not available. By putting the springs under the bed mounts to hold the print bed down I was able to use thumb screws on top of the bed mounts to adjust the height of the bed.