The Print3r

Heat sinks will help keep the extruder stepper motors cool.

I had to buy longer screws to properly mount these.

Especially since they are geared down, the steppers will run fast continuously -potentially leading to overheating.

I skipped the thermal paste for now - if they still run hot I have the option of adding some later.

The print head assembly is a customized version of the Wim3rl.

"This head is an all-in-one solution, where the cooler and hotends are one stiff, durable and heat-resistant package. The head weights only 80 g (not including heaters and connectors to tubes and hoses) when filled with water, being as heavy as a common plastic part with the hotend and cooling components.”

https://www.kickstarter.com/projects/1057128232/wim3rl-water-cooled-print-head-with-3-nozzles-for

Despite an unsuccessful kickstarter campaign Mathias was extremely helpful and produced this customized version for me adapted to the magnetic push rod ball ends.

Looking up:

After an exhaustive search of practically every silicone pad/pan/trivet/sheet... available on amazon I settled on the "Heavy Duty Silicone Hot Pad Trivet, Circle, Large (9 1/8"), Dark Red":

https://www.amazon.com/gp/product/B00T92X2Z0/ (They seem to be out of the large now)

It is 6mm thick with raised ridges on both sides (included in the 6mm) and rated to over 200 degrees celsius.

Here is the trivet as it arrived:

I used a 220mm glass plate as a template:

Trimming the excess:

I went through several drill bits trying to make these holes to mount the heated bed. Here is the finished plate:

In order to route the power and thermistor wires to the control board I used an high speed cut-off saw to chop out a hole in the center of the stainless bed support plate.

This turned out to be pretty difficult as this stainless plate is 3mm thick. The heat caused it to warp slightly, but I was able to (with the careful application of force) flatten it out again.

Closeup (the bottom is not this nice looking):

This was a 12v aluminum heated bed - I later swapped it for a 24v version. The process was the same however. To start I milled out a small pocket to hold the thermistor:

Finished pocket:

A tiny copper sheet cut to fit the pads intended for the LED indicator:

Securely held in place by the soldered copper sheet:

Lots of kapton just to be safe:

You can see all of the important connections in the cooling loop here:

On the left is a 500L/h pump with a built tank.
https://www.amazon.com/gp/product/B00VHPADRW

The silicone tubing is undersized for the pump connections, but I was able to force the tube into the connectors (rather than over). To stabilize and further seal the connections larger latex tubing was stretched over the whole thing and zip tied to lock everything down.
https://www.amazon.com/gp/product/B013SYAVIU

No doubt this restricts the flow - although it still works quite well thanks to the over-specked pump.

The upper pump connector feeds the print head assembly, then the hot returning water goes into the radiator. The radiator is sandwiched between two 120mm fans to ensure sufficient airflow.
https://www.amazon.com/gp/product/B00CFDS3JA
https://www.amazon.com/gp/product/B000O8I474

The cooled water exits the radiator and re-enters the pump through the lower connection.

I repurposed one of the fan outputs to control the cooling system. Both the pump and the fans run on 12v, but the rest of the system is powered by a single 24V supply. The Rumba board includes a fairly powerful 12v switching regulator - but this seems to have been intended to only power one or two fans. Rather than risk it - I configured the Rumba fan output for 24v (this is a jumper setting) and connected that to a small 12v regulator. The pump and fans are then connected to the regulator.
https://www.amazon.com/GERI-1-25V-30V-converter-Constant-Adjustable/dp/B013WKRDKE

Mid-Print on the first successful object! (with a traditional single extruder...)

Finished Object:

Two types of stepper motor drivers are utilized on the Rumba control board - the DRV8825 is configured for 1/32 microstepping for the XYZ steppers. The Trinamic TMC2100 which features 1/256 microstep interpolation is used for the extruders which provides extrusion consistency and speed.