As part of my CoreXY Toolchanging build, I need a number of extruders. I wanted to explore the different options available. As great as the E3D Hemera looks, I can’t justify the £108 cost per extruder (and for my CoreXY I need 6) when I wouldn’t need all the added benefits for every extruder.

I had a look around on my favourite source of parts (Aliexpress) and found the Mellow BMG Extruder. I’ve had my eye on Mellow branded items for a while now as they seem to be up and coming in the cheap knockoff world. They have even cloned the Mosquito Hot End, which so far seems to be reviewing well and at some point I may well order one.

I ordered the Set 2, which comes with the extruder and the motor. Everything came nicely wrapped in a polystyrene box. The main body is injection moulded, as is the larger driving gear. The machining of the teeth on the gears look good and I am generally happy. The purple piece in the photo below held the gear which fits to the extruder in place which I thought was a nice little touch, and is not needed for every day use. The plastic gear has also been mounted centrally on the shaft so rotates correctly when installed. It looks as though Mellow have decent quality control.

In the kit you get all of the tools required to fit the extruder as well as the fitting to allow it to be used in bowden mode. I will be using this extruder in direct mode. There are also two lengths of screws to be used to fit it either directly to the motor or with a mount in between.

I only had one issue with the extruder in that the way I mount it on my machine. The BMG clone when assembled is slightly thicker due to the name badge and the “waves” that have been moulded into the plastic in the front. So I had to spend a little time sanding the front down to get it to fit in my custom mount.

I have yet to print with it (still assembling the printer) but at the moment, the Mellow BMG clone definitely looks like a very good purchase.

As well as building a new corexy for myself, my Dad was interested in a CNC router. He does a lot of woodwork and wanted a quick way to make 3D engravings. So we’re building a Root 3 CNC Lite.

The Root 3 CNC Lite is made out of a mixture of 3D printed parts, 20mm square box section and a number of other vitamins. It uses Nema 17’s to control the motion.

We have chosen to use a 500w air cooled spindle for the cutting and rather than use a ramps board for the electronics, we have gone with a Duet 2 Ethernet.

We have so far received the side panels and base ordered from the online shop and I am busy printing all the required parts.

Once the BOM is confirmed, I will upload. This will give an idea of price and links to where we got the parts from. The BOM on thingiverse is not complete.

My early christmas present has come in the form of a shiney new Duet 3 board. Those of you who have read my earlier posts know that I have used Duet 2 ethernet boards (although they were clones) on both the Anycubic Linear Plus and the Anycubic Predator. They are a fantastic board for the money so it made sense to look towards the duet family for my new corexy.

But why did I choose the duet 3 over the duet 2? Well there are a number of reasons why I have done so.

  • The duet 2 tops out at 10 drivers (duet 2 + duex5). If I populate my corexy with all tools, I would need 12 drivers. The duet 3 should be able to handle at least 24 drivers, so expansion isn’t an issue.
  • The duet 3 can be configured to use a raspberry pi (or other similar SBC) to serve the web control, store the gcode files etc and allow the use of plugins with the reprapfirmware. I have been using raspberry pi’s for a number of years with the smart home system so I have a number of them around.
  • As my bed is 500x500x500, I felt that using 3 nema 17’s to move it would be getting towards the top of its limits. I know that its possible to find nema 23’s that would be suitable for use with the duet 2, I didn’t want to restrict myself. The duet 2 can handle up to 2.4 amps per driver and the duet 3 can handle 4 amps.
  • There are individual tool boards planned that would be mounted to the extruder. This reduces the number of wires to each tool from ~12 to 6 (4 for the canbus and 2 for power).
  • The processor has been increased from 120MHz to 300MHz.
  • Any HDMI screen can be connected to the SBC to run the web interface. You are therefore no longer restricted to the paneldue interface.

Now I’m not saying to go out and upgrade a duet 2 to a duet 3 as for standard 3D printers, the cost can’t be justified. But if you are building a tool changer or a larger CNC machine, the duet 3 is a no brainer.

If you do order a duet 3, the following things are supplied:

  • All connectors and crimps to use every connector on the board.
  • A 26 pin cable to connect the duet 3 to an SBC.
  • The crimps required to connect the power cables.
  • An SD card for use in a raspberry pi. (I haven’t used this as my raspberry pi 4 was already setup with an SSD).
  • A sticker for your machine to show that its using a duet 3.

So far, I have the duet 3 setup with a raspberry pi 4Gb. I have updated it and that’s about as far as I’ve got. I have a couple of motors that I’m going to use for the X and Y. I also have the motor that I’m going to use for the tool changer. I have ordered the Z motors (3 off) as well. I’m still on with building my machine so it will be a while before I actually start doing any electronics wiring. Eagle eyed readers will spot that all those motors above equal 6 and there are only 6 drivers on the duet 3 mainboard. I have preordered an expansion board to give me 3 extruders.

More updates on how the build is going to follow.

Yes, I know I’ve been a little bit quiet on here to the point where I haven’t posted in over a month. I’ve been fairly busy with home life (visiting friends on weekends etc) and working away from home in different parts of the country.

I’ve also been working on the design for a new 3D printer. As some of the more regular readers will know, I have/had an Anycubic Linear Plus (ALP) and an Anycubic Predator. Both with a number of upgrades, with the main one being duet 2 control boards. Well the ALP has been sold and I bought a Da Vinci Jr 1.0 for £35 + postage off ebay to tinker with.

The main reason I sold the ALP was to generate funds for a new printer. A coreXY in fact, with built in toolchanger. I was blown away with the possibilities of the E3D toolchanger when I was TCT but the ~£3000 asking price almost made me fall over (I was also impressed by the E3D Hermes and needed an excuse to buy a duet 3). Since then I’ve been researching different toolchanging printers (shout out to the Jubilee printer) to see which design I liked. I knew my next printer was going to be a coreXY and I knew I wanted something a little larger and I couldn’t really find anything I liked.

So Jays Toolchanger CoreXY was born. If anyone comes up with a better name, please let me know in the comments below.

I had a few design goals in mind. Namely I wanted to print roughly 500x500x500, use the duet 3 with toolboards, be fully direct drive and to use as many 3d printed or off the shelf parts as possible (as it stands at the moment, only the locking pin and bed need to be custom machined, although once the locking plate is easily available, I will swap to machined ones).

All files are currently available on Github and Thingiverse and comments on the design are welcome. I have tried to make it as accessible as possible. All of the design work is done in Solidworks.

As it’s all the rage these days, there is also a discord server. Come join me for a chat.

I will add another post with build progress.

I’ve always fancied upgrading one of my machines to a volcano hot end. Both of my deltas currently run genuine E3D v6 but as I slowly tweak them and increase the print speeds, my limiting factor will be how quickly I can heat up the plastic to squirt it out.

Hence the reason why E3D created the volcano (and super volcano – but why?? Just look at one).

Being a bit stingy, taking an interest in titanium heat breaks and also in non aluminium heated block (think brass or copper) I started to look around for alternatives.

That’s when I stumbled on TCMUK-3D and their titanium heat break and volcano upgrade kit. The kit is available directly from them here or through amazon here.

In the kit you get the following items.

  • Either a 40w or 60w heater cartridge in either 12v or 24v with extension cable (I went for a 60w 24v one).
  • A thermistor with extension cable (more on this later).
  • A titanium heat break
  • 3 x Stainless Steel Nozzles (0.6mm, 0.8mm and 1.0mm).
  • 3 x Brass Nozzles (0.6mm, 0.8mm and 1.0mm).
  • The required fixings.
  • An allen key.
  • Thermal paste.

Assembly is via the normal E3D assembly instructions.

Now this is the only negative thing I have to say about this kit. The thermistor is, well, rubbish. It doesn’t really conform to any current thermistors in marlin (although they suggest you use number 5 as its closest) and I’ve not had great success in the reprap firmware. They provided me with a copy of the datasheet but that didn’t really help. So my word of warning is use a different thermistor or buy a PT1000.

I am waiting on a new thermistor to come but in the mean time I have battled on with getting it to print as it is, althought not being 100% sure of the temperature I’m printing with. Below are a couple of examples I have printed.

Would I buy this again? Yes, definitely. Its good value for money. I would just use another thermistor.

Whilst I was attending TCT today, E3D made an announcement about their new extruder, the E3D Hermes.

They have taken a dual drive extruder and created their own version. How is it different I hear you say? Well…

  • All of the gears are metal and fully hardened.
  • Each groove in the drive gear is custom milled (they have followed the crowd and announced they were manufactured on a swiss lathe), rather than using a tap.
  • There is no lubrication required due to the type of material chosen for the gears and the use of Igus bearings.
  • The extruder body is made of aluminium with optimised airflow, allowing for the use of lower powered fans. The airflow is directed upwards and away from the print area.
  • A custom nema 17 motor is used. The end caps od a standard nema motor are replaced with custom die cast and machined parts. These allow for the bearing recesses to become part of the motor casing. T-slots have also been machined into the caps to aid in extruder mounting and mounting other objects to the extruder, such as a BLTouch.
  • All items that require user interaction are at the top, such as idler tension and release.
  • It is smaller than their current titan aero extruders.
  • They are following Prusa and will be allowing the QC information of the extruder to be followed all the way through.

The E3D Hermes will be released as a complete package, contain the custom motor, extruder and hot end (including a nozzle, heater cartridge and thermistor).

I know what you’re thinking, this sounds expensive. They have made sure that the extruder can be manufactured using mass manufacturing techniques and have promised a price significantly less than £100.

The most crucial bit of information is when is it available? 4-6 weeks from now. So November.

Pictures of a production prototype and slides from the presentation are below. Ignore the PCB on the extruder, that is a whole other story…