Ender 3D printer upgrade(s)

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Ender 3D printer upgrade(s)  or an attempt to turn my latest buy into something more useful, capable of printing well at much higher temperatures.

The requirements were fairly straightforward :-

1. Auto bed levelling - For good first layer adhesion every time. BLTouch knock off (3D Touch V3.0) £14.36  Early days but it seems very accurate and repeatable.

2. Mains powered silicone pad bed heater. ABS, Nylon and Polycarbonate all need this, and while the std bed will eventually get up to about 110C (max recommended is 85) and it takes forever to do it. Mains powered ~ 560W bed <2 mins to 110C. £19.15 +£1.57 thermal fuses.

3. Magnetic bed - clips work but are time consuming and a nuisance. Never really sure how flat the bed is in the middle, and whether the bed is heated evenly. Spring steel with pei coating (13.76) is pretty good, but high temperature rubber compound (130C working) is OK too. £8.76

4. Touch screen Controller tft35. My fingers are too big for micro sd cards, the reprap graphics display with its slow response quickly loses its appeal. Touch screen controller allows use of std usb sticks, and more interface options. Very much faster to work with. £21.86

5. 32 bit controller card, SKR 1.3,  for bed levelling and Marlin 2.0x. £11.36.

6. TMC2209 stepper drivers (£14.42, 4 + 1 spare) for sensorless endstops and firmware current adjustment. £11.36

£105.24 total

The only part I didn't expect to need :

Metal Extruder. Came with Levelling Springs, 1.9mm PETG Tube, MK10 Silicone head boot. (£3.18)  Excellent value for money and so much easier to insert filament. Price now is nearly double plus carriage.

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Silicone Bed Heater installation.

*** Warning  This instructional involves mains voltages which can be lethal  - Proceed at your own risk ***

For this you will need :-

1 A 3mm Aluminium sheet 235x235mm with 4off 4mm countersunk holes spaced centrally at 170mm.  My attempts to remove the heater from the original bed were doomed to failure.

2 A mains powered silicone self adhesive heater pad.

3 A solid state relay with cover. If possible use a similar style as the one shown. Although small 2-3A SSRs are available they are likely to fail due to overheating. The one shown is 25A rated (allegedly) but this is only if fitted to a very large heatsink. At the 2.5A needed (or 5A @110v) This style is adequate for the task. It will also drive directly from 24V.

4 A thermal fuse. Don’t skip this. Its cheap to install and will protect from overtemp faults. Crimp only. Do not solder unless using a heat shunt. See picture above.

5 Clear silicone sealant - generic stuff seems to work OK at these temperatures.

6 Various connectors crimp, jst etc, and scrap for cable support with strain relief.

After cutting drilling and countersinking the 3mm aluminium sheet to size, clean the underside and degrease with acetone. Align and affix the heater pad.   

Cut one of the pad mains leads and insert a thermal fuse (155C)  using crimped connections - see picture. Hold the fuse in contact with the rear of the heater and fixed in place with clear silicone sealant. Leave to set up overnight.

Check for continuity of the heater with a multimeter ~103 ohms on mine. If you are not using a rear mounted case you will need an insulating enclosure to house the solid state relay. I used a surface mount switch box and blanking panel on my last printer. I have attached files (RSDOC and STL) for my rear mounted case which I derived from the teaching tech offering (https://www.thingiverse.com./thing:3688967). I fully enclosed the electronics to promote more controlled forced air circulation.  Feel free to amend as suits. The fan is the original ender cooling fan, but it is quite noisy. Although a space is left for an RPi (Octoprint), I do not intend to use this. I may use an old phone for video monitoring and intend to use ESP3D for wifi, connected to the tft35 display. More information on this can be found at https://github.com/luc-github/ESP3D,
with instructions :
https://github.com/luc-github/ESP3D/wiki/Install-Instructions
and firmware :
https://github.com/luc-github/ESP3D/releases/tag/2.1

A cable support bracket is needed for the printer Y plate. I made mine out of 0.7mm galvanised steel scrap which was part of a casing. Print out the drawing  and stick it to the metal, then cut round it. Bend the folds and drill the holes. Position the bracket on the printer Y plate and mark through the mounting hole with a felt tip. Use this position to drill the 4mm mounting hole. I used a PG7 for cable support, with a 0.5” mounting hole. Obviously drill the bracket for the cable gland/strain relief of your choice.

Assemble the bed to the Y plate with the original M4 countersunk screws as shown in the pictures. Use upgraded springs if possible as they greatly improve the stability of the bed. If you wish to add an earth connection to the bed do so at this stage.

Feed the cables through the strain relief and fit suitable cable protection. I used heat shrink and braid.

Remove the plastic power supply cover from the ender 3 psu. Connect one end of the heater pad mains cables to a mains terminal on the psu, and connect the other to the SSR AC voltage terminal. The other psu mains terminal should be connected to the other SSR AC voltage terminal. If using an earth ensure it is connected to the psu ground. See schematic attached.

Crimp and fit a 2 way JST connector to the thermistor leads and plug into the bed thermistor connector on the control board.  If you cannot crimp a new connector cut one off of unused part and solder the thermistor to it, not forgetting to use heat shrink sleeves to insulate the connections.

The low voltage SSR terminals should be connected to the controller board bed outputs, observing the correct polarity.

Check it out with a meter and ensure that the covers are replaced on the psu and SSR enclosure. Be safe.

Ensure that Marlin has the correct bed thermistor selected (mine used a 3950) , and select #define PIDTEMPBED for best control. Run either of the two attached gcode (zipped) scripts to autromatically set and save to eeprom the pid values for abs or pla.

Stand back and watch the bed heat up in seconds, <2mins to 110C

Best Regards

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[Brass_Machine]

Very cool... I will be watching this.

Right now, I have more money on in mods then I spent on the printer... easy hole to fall into.