Titan printer front view with door off.

This printer is based on the RepRap principle with all parts readily available and all designs open source.  Furthermore, this principle often makes use of one 3D printer to make parts for another and this printer embraces this principle wholeheartedly.

The construction is based on a box to provide the main framework and this also provides a fume cabinet for using ABS filament which gives off noxious fumes when printing.  To provide views of the printing process three sides and the top of the box are clear acrylic sheets.  An opening front door provides access.  Base and back are currently 6mm plywood with appropriate bracing but I'm considering replacing it with thicker material.  In line with the RepRap principle the corners of the box are made from many 3D printed plastic sections including door hinges and catch.

For the main movements in X, Y and Z directions, V-slot aluminium extrusion is used in combination with matching ball bearing wheels.  This provides smoother, more accurate and more reliable movement than stainless steel round rods and linear bearings.  It is also a lot lighter than stainless steel rods.  This printer (as can be seen) moves the nozzle in the XY plane and the print bed to provide Z motion.  This arrangement was chosen because the X and Y axes have the main movement and reduces the effective moving mass.

The drives use ultra-low stretch and very strong fishing line cord rated at 100lbs breaking strain.  This is driven by drums and runs over ball bearing pulleys for the X and Y drives.  This arrangement uses fixed motors and avoids having their rather high mass on moving parts.  The Z drive uses 3D printed spur gears to provide a reduction drive from stepper motor to drive drum.  The drum is on a horizontal axle and simply lifts or lowers the bed with cord.  As with the X and Y stepper motors, the Z motor is also mounted on the back panel.

The box makes use of 500mm square x 4mm acrylic sheets providing right-angle corners.  The build volume is about 300mm (1ft) cube.  The printer has been designed to be capable of printing with any sort of filament of 1.75mm diameter with an extrusion temperature up to 300°C and bed temperature up to 150°C, though I have only tried with 280°C and 110°C.  I am currently using a 0.8mm nozzle though other sizes are available (0.4mm, 0.6mm, 1mm and 1.2mm).  Printing surface is borosilicate glass 300mm square which is heated with a 24v 300W heating pad.

The electronics uses the RepRap standard Arduino Mega 2560 microprocessor board and the RAMPS interface board, powered by a PC style ATX PSU with +5v and +12v power rails and providing the power for the stepper motors and hotend heater etc.  Power for the print bed heater is provided separately by a 24v PSU.  Heating is quite fast taking about 4 mins to get from 20°C to 100°C.

I had originally designed this printer to use Bowden filament feed but this proved so troublesome that I made the decision to use direct feed with a small, lightweight extruder and stepper motor mounted on the X carriage.  This is the E3D Titan Extruder (the name is a coincidence - I named my printer before their extruder came out) and is not only small and light but is reckoned to have a superior hobbed shaft.  I am also using their Volcano hotend with better filament heating and flat ended nozzles.

In addition to the 0.8mm nozzle I have also been printing with a smaller 0.4mm nozzle and produced quite high resolution prints using 0.3mm or 0.2mm layer height.  Both these nozzle sizes have been used with ABS, PETG and TPU filament successfully.  The genuine E3D V6 hotend with E3D Volcano heater block and nozzles has enable printing with the very soft and stretchy TPU filament which needs good support right from hobbed shaft to nozzle.

I am now printing with a large 1.2mm nozzle which this larger printer was originally designed for.  The Volcano heater block and nozzles provide much faster heating and enable speeds of 50mm/s even with the 1.2mm nozzle.   So far I've used only PETG filament with the 1.2mm nozzle.   I'm using a 1.0mm first layer height with 120%  filament feed whilst the rest are with 0.8mm layer height and normal 100% filament feed rate.  I'm using half speed printing for the first layer to help with adhesion to the print bed.

Software is Repetier Host with CuraEngine slicer.  Firmware is the latest version of Marlin.

Table of Volcano Nozzle Sizes :-

Number of Dots    Nozzle Diameter
           0                      0.60mm
           1                      0.80mm
           2                      1.00mm
           3                      1.20mm
           4                      0.40mm

I'm trying to go back to the 0.4mm nozzle but it's bunged up - apparently with TPU filament but I can't seem to shift it   I have it heated to 290°C and the red TPU is slowly dripping out and a tiny amount will come out when Nylon filament is pushed hard down into the nozzle from the top.  I need some 0.4mm steel wire to push through...

I found a resistor with wires less than 0.3mm diameter and managed to push that up into the nozzle when hot but it still didn't clear the nozzle.  I have now put a 0.6mm nozzle in and will order another 0.4mm nozzle (or two) - it's not worth spending too long trying to recover a nozzle that costs less than a fiver.

I've put a 0.6mm nozzle in the Volcano hotend and set up for that - printing is now fine particularly with PETG.

I have also used this printer with ASA and Nylon successfully.  It has been my"workhorse" printer recently since my "Pilot" printer was having problems.  The "Pilot" has now been dismantled and replaced by my "GinaRep Mini" 3D printer which is virtually finished and working very well.

The large size of this printer is really too much for the living room which I am tending to return to normal use rather than a workshop, having mostly cleared out the room I want to use as a workshop.  Hence the Titan printer will be going in the workshop.  With this in mind, requiring remote operation and the results of using a more advanced control system on my Mini printer, I am about to upgrade from Arduino Mega and RAMPS to the Duet WiFi control board.  This uses a web interface with total remote control from a web browser.

Gathering data for the Duet from the Arduino Mega.  X=59.5s/mm, Y=59.5s/mm, Z=515s/mm, E=418.5s/mm.  Z probe offset=-2.5mm.  I'll have to measure the Z probe XY offsets.

Duet WiFi control board all set up and ready to connect up.

The mains voltage heater pad I ordered has arrived so I'm ready to upgrade the bed heater and avoid using the 24v PSU for bed heating.

Been stripping out the RAMPS etc. ready for the Duet board.

Still on the re-wiring.  A few changes needed to the layout.  More to do than I thought!  Coming on though.  I guess this would be a good time to swap the bed heater for a mains one but I would prefer to take one step at a time and continue to use the 24v 300W one.  I'll change the bed heater when I change from 12v to 24v.  I'm going to continue with a 12v main power supply ATM.

Phew!!  These 3D printers don't half have a lot of wiring!!  Let's see what I've done...

1. Main power - 12v from ATX PSU.
2. Bed heater wired up.  24v PSU negative to power Gnd, positive to bed heater, other bed heater wire the BED terminal on Duet board.
3. Bed thermistor plugged in.
4. Hotend heater connected.
5. Hotend thermistor connected.
6. All four motors connected.
7. Endstops wired up, including Z probe which needed resistor divider replaced with Schottky diode.

24v PSU needed moving to reduce wire lengths.  Hotend and fume extraction fans to be wired up.  Part cooling will be added later (not needed for ABS).

Forgot one thing - the ATX PSU PS-ON and +5v-SB.

Connector for +5v-SB and PS-ON wired up to PSU and plugged in.  Connector for hotend fan wired up and plugged in too.  I still need to mount the Duet board but I think the wiring is all done now.

Having moved the 5v power link fro internal to external, it works   Now testing.  Web interface works so I'm controlling from that.  Enabled ATX power control and turned PSU on.  Hotend fan started up noisily   That's connected to an "Always ON" connector so it's on all the time the ATX PSU is powered up.  Tested X and Y endstops and they're alright.  Now to test the motors - some are bound to go the wrong way

Ha ha.  Not only are some going the wrong way but I got X and Y mixed up.  I was thing the top motor was X but it's Y   Silly ass!  I'll power down and switch off and swap the plug over.

XYZ motors now working correctly though the Z seems very noisy - much noisier than before.  Both heaters and thermistors working.  Extruder motor turning in the right direction.  Z probe working. 

I think that's all the pre-printing tests completed so I guess I could try a print.

Filament loaded and warming up ready for the first print with the Duet WiFi control board.

Z homing didn't work properly   It raised the bed and the Z probe endstop light came on but it didn't stop until the bed hit the nozzle.  Then it was a case of "Emergency STOP"!  I seem to remember having this problem before - I'll check...

Found it

M558 P4 H7 F600 T6000 I1                 ; Set Z probe type to unmodulated and the dive height + speeds

I1 needed to specify that the probe goes low on detection.

Z homing worked but it didn't do the bed levelling routine.  Setting up a 3D printer always seems to need sorting out at every step however many times you've done it before and copied code and instructions from previous setups!!!  Nearly there I think but I don't know how many other things are wrong.

I was hoping changing to the Duet control board would make the printing motion quieter but it hasn't   X and Y movements are about the same but the Z is distinctly worse.  Strange because the Mini is very quiet.  There are one or two differences - the Mini uses CoreXY whereas the Titan is Cartesian with separate drives for the X and Y and hence more pulleys.  Also the pulleys on the Mini are bigger.  It may be worth changing the Titan to CoreXY but I don't know if it will make all that much difference and it would be a fair amount of work.  Also, I'm planning to move the printer out of the living room into the workshop when I've set it up with a camera so the noise will be a lot less important - as long as it prints well.