Upgrade Anycubic 4Max Pro Hotend PTFE
Upgrading the PTFE tube in the Anycubic 4Max Pro hotend to high temperature Capricorn tubing.
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Introduction
The Anycubic 4Max Pro printer’s hotend uses a piece of ordinary PTFE tubing between the nozzle and the extruder. At higher extruder temperatures this PTFE tubing can melt, causing clogs. To be able to work with higher temperature filaments this ordinary PTFE tubing needs to be replaced with something that supports higher temperatures. In this article it is replaced with a piece of Capricorn tubing.
Disassembly of the Hotend
This section describes how to remove the hotend from the printer.
Warning!
Make sure the printer is disconnected from power and the hotend has cooled down.Removing the Toolhead Cover
The toolhead cover must be removed to gain access to the toolhead components inside. The toolhead cover is secured by four Hex M2.5 screws. The two at the rear are accessible from above. The other two at the front are accessed from underneath.
Once these screws have been removed, the cover should lift off. Be careful to free the toolhead ribbon cable from the cover.
Removing the Hotend
First disconnect the connectors for the hotend heater and thermistor from the toolhead circuit board.
The picture shows the heater wire disconnected from the socket in the rear row, left. The thermistor was disconnected from the socket on the front row, second from left.
The hotend is held onto the extruder by a single Hex M2 screw at the front. Only unscrew this screw a turn or so, just enough to release the hotend when gently pulled from below.
Warning
This screw is held in place by a captive nut and if you unscrew it too far, this nut will fall out and will need to be refitted.It will be easier to extract and refit the wires for the hotend if the extruder is removed from the toolhead. The extruder is secured by two Hex M2.5 bolts located at the front base of the extruder.
Unscrew these until the extruder is loose and can be moved to the side.
It should now be possible to pull the hotend down and out, feeding the hotend wires through the hole in the toolhead base.
Replace Hotend PTFE Tubing
With the hotend removed from the printer it is easy to see the white PTFE tubing that needs to be replaced. Pull this out of the heatsink.
Note
The length of this PTFE tube is critical in this printer. It is very hard to find a definitive statement for how long this tube should be. Anycubic seem to treat this information as a state secret. If you have the original hotend that came with the printer, you can just measure its length. Scanning the web, it seems to be that this tube must not be less than 51 mm, and can maybe be up to a few mm more.The Capricorn tubing that is used to replace this PTFE tube must be cut to length and the cut ends need to be square to the tube to avoid issues. It is best to use a PTFE cutter to ensure the ends are square and clean. I 3D printed this one and it seemed to work well.
Cut an end of the Capricorn tube with a sharp knife to ensure a straight edge. Insert some filament into the tube before cutting to ensure the tube does not deform during cutting.
Then measure the length of the tube needed and cut the other end. I aimed for about 54mm length.
Insert the cut length of Capricorn tubing into the hotend.
Reassembly of the Toolhead
Reassembly of the toolhead is essentially the process of removal in reverse.
Feed the hotend heater and thermistor wires through the hole in the toolhead base that is beside the print cooling fan hole. Then offer the hotend to its hole in the toolhead base, pushing up until the Capricorn tubing emerges from this hole in the toolhead base. The hotend should be orientated so that the wires emerge from the right when the hotend is viewed from the front. Keep pushing up until the hotend heatsink is fully inserted into the toolhead base.
When the hotend is correctly inserted into the toolhead base the top of the heatsink should protrude from the toolhead base and the flat surface on this toolhead should face to the front so that it will be gripped by the toolhead securing screw.
The extruder can now be reattached. When offering the extruder to the toolhead base, ensure the toolhead wires are routed to the rear of the extruder and between the part fan and extruder motor. It is essential these wires are nowhere near the extruder mechanism. Gently lower the extruder so that the Capricorn tubing is inserted into its hole at the base of the extruder. Also ensure the hotend wires are not trapped below the extruder. Once the extruder has been settled into position on the toolhead base, it can be secured with the two Hex M2.5 screws inserted from the front. Note the longer screw goes into the hole on the left.
Next secure the hotend by tightening the hotend screw until the hotend is secure. The hotend screw is the M2 screw between the two extruder securing screws mentioned above.
Finally the hotend heater and thermistor connectors should be reinserted into their sockets on the toolhead PCB board. The larger connector for the heater goes into the empty connector on the second row of the circuit board. The smaller thermistor connector goes into the second from the left socket on the first row of sockets on this board.
Now the toolhead cover can be installed. Slide the toolhead cable into its slot on the cover. Then the cover can be lowered onto the toolhead base. It is secured by 4 Hex M2.5 screws. The two at the rear are inserted from above. The two at the front must be inserted from below.
Final Steps
As the hotend has been moved, the bed height needs to be reset to the new hotend position and the bed levelled. The procedure to do this is described in this bed levelling guide.
Before the toolhead is used PID tuning of the hotend should be carried out using the normal procedure for this. Since my printer is running Knutwurst Marlin 2 firmware, there is a special menu for this in its “Print” menu.
