Adding MK3 heatbed to Vertex K8400 by Bo_Ris

Last crawled date: 3 years ago

Adding heatbed to VERTEX K8400 is not as difficult as one may think. Here is the list of parts that I used:
MK3 heatbead
Velleman's 24VDC 150W power supply
3D Printer Heated Bed Power Module
NTC 3950 100K Thermistor with Wiring
Heat resistant silicon
Sheet of 5mm cork
Several M3 screws
Several 3d printed parts
I bought the parts from reprapchampion.com They have good prices and ship the same business day. I also purchased 2 pieces of Borosilicate Glass 219x219mm, but so far I was not able to find a good way to mount them on top of MK3, which is 220x220mm. That's why at the moment I'm using the original 4mm glass that came with K8400. Binder clips could be an option, but they take space and complicate glass installation and removal. Ideal solution would be to buy a bigger 3mm Borosilicate glass and cut it to the dimensions of the original glass (240mm x 215mm).
Attached Files
I am attaching several STL files, but the only one you really need is called corner.stl. Four corner things keep the original glass in place.
Corner.stl was designed to fit the "sandwich" of the original aluminum bed plate covered by 5mm cork sheet with MK3 heatbed on top of it.
side.stl thing stops the glass from side movement. It is optional, as the corner things do the same.
bottom_under.stl, top_center.stl, heatbed_connectors.stl, heatbed_connectors_cover.stl and bottom-center.stl files are for those who installed my wire covers posted here. Old wire covers need to be replaced to accommodate additional wires.
center_mount_bottom.stl, center_mount_TOP.stl and center_mount.stl things are mounted to the center of printer’s bottom panel. center_mount.stl houses Heated Bed Power Module and Raspberry Pi’s power supply board; I extracted it from Pi’s standard power supply. center_mount_TOP.stl is just a decorative piece that you can glue on top of center_mount.stl to cover the fan opening in bottom panel. center_mount_bottom.stl is the bottom cover for center_mount.stl. It also holds Raspberry Pi’s power supply board in place.
power_supply_safety.stl thing covers the connectors of 24VDC power supply, to protect user from accidentally touching them.
Wiring
You will need to add 5 sets of wires:
1) Connect AC power cord or power switch to newly added power supply (2 wires + ground wire)
2) Connect power supply to Printer Heated Bed Power Module (2 wires)
3) Connect Printer Heated Bed Power Module to MK3 bed (2 wires)
4) Connect thermistor attached to the heatbed to the mainboard (2 wires)
5) Connect mainboard to Printer Heated Bed Power Module (2 wires)
If you have Raspberry Pi mounted to the printer and want to move its power supply into center_mount.stl thing, you will need 2 additional sets of wires:
6) From AC power cord or power switch to Pi power supply card (2 wires) and
7) from Pi power supply card to Raspberry (2 wires)
How to run the wires is up to you. It will depend on where you install 24VDC power supply and power module, and if you want heatbed to be removable. I opted for the later and installed additional connectors for the wires going towards MK3. I used 2 Position Terminal Strip as 24VDC connector and 2 Pin 0.1" Polarized Locking Header for thermistor wires. They both are housed in center_mount.stl thing. Thermistor connector is soldered to a little piece of prototype board that slides into center_mount.stl thing from the back.
Assembly instructions
Start with gluing the thermistor into the center hole of MK3 with heat resistant silicon. It will take about 24 hours to completely dry.
Print all the things posted here, but do not change the position of Z-stop sensor. Drill the hole in aluminum bed plate as shown in the image from that post.
Drill 6 additional holes in the bed plate. 4 holes with 3.2mm diameter should be aligned with the mounting screw holes of MK3 (see image). Put MK3 on top of the bed plate, align it to be in the very center and mark 4 points to drill. 2 other holes with M3 thread inside are needed for front-left and rear-right glass holders. Bed plate already has similar holes in 2 other corners (see image).
Print 4 copies of corner.stl thing. ABS would be the preferred option. Use 0.2mm resolution.
Once all parts are available, start from locating the place where you mount 24VDC power supply. If you printed and intend to use cente_mount thing, install it temporarily and then find the place where you can fit 24VDC power supply. The way I mounted mine is shown on attached images. You will need to drill 4 holes in the bottom panel of the printer for M3 mounting screws. Use 5mm high spacers to keep distance between the power supply and printer’s bottom panel. Mounting screws should be M3 x 12mm.
Use four M3 x 6mm screws to mount heatbed power module to center_mount.stl thing. Raspberry Pi power supply board simply slides in and does not require screws.
Place MK3 on top of cork sheet and cut the cork along MK3 edges with sharp knife. Cut the “channel” in the cork along the thermostat wires. Cut the cork around MK3 soldering pads and mounting holes.
Put all things together as shown on the images. While installing wiring make sure to properly connect the positive and negative wires, where applicable. Use pads #2 and #3 to feed MK3 with 24VDC. If you purchased 12VDC power supply, connect pad #2 to pad #3 and feed 12V between these 2 pads and pad #1.
No firmware changes are required. Mainboard detects the presence of heatbed as soon as you connect heatbed thermistor to it.
Update 21-June-2017
Uploaded new revision of heatbed_connectors thing. Relocated thermostat connector and added cover.
Update 16-April-2018
Uploaded corner and side Things for 1mm thick heatbead.