Flashforge AD5X - Ender 3 style hotend mod

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Modified print head for the Flashforge AD5X that uses an Ender 3 style toolhead.

I designed this as a temporary substitute for a dying hotend, while I waited on a replacement to ship. Did I end up printing anything with it other than revisions of its own parts? Only a single test print. Was it fun and interesting to make? Heck yes (except the soldering part).

A few warnings:
- This is very much an advanced mod. If you're relatively new to modding, consider doing some lower-risk mods first like recirculation / exhaust ducting or an IFS Jacker.
- As such, the instructions will assume you know your way around disassembling the stock print head, and will not explain how to do so. If not, refer to this video from Flashforge.
- Some slight tweaks were made to the model after I printed it, that I did not reprint to test. They are very minor changes (length of the fan screw holes, and the exact positioning of the cable passthrough) that I am confident enough in without retesting, but I am mentioning this just in case.
- Seriously, don't cut corners on materials. ABS is the bare minimum.
- That being said, ABS itself is the only material I've printed and tested this in.
- ABS is also the only material I've tested printing with this mod.
- Only the hotend is replaced. Aside from this, stock parts are used.
- The clearance on the poop chute flap with this mod is extremely, EXTREMELY tight. You may want to file down the top of the flap, or even replace it with a custom one, if you intend to use this mod long-term.
- This has not been tested long-term. As mentioned, I intended for this to be a temporary substitute while waiting on a replacement part; and in the end, new iterations of parts for this mod (especially the corresponding part fan cover) are all I ended up printing with it.

You will need:

• About 35g of filament. ABS is the absolute bare minimum; PC or PA-CF would be better if you're able to.

• Screws: Two M3x6, two M3x10, two countersunk M3x18, plus most of the screws from the stock print head

• Magnets: Two 5mm x 2mm circular magnets

• Heat inserts: 14 x M3x4x4.5 or M3x4x5 inserts. The author of the original model I remixed recommends M3x4x5; but I found a better fit for M3x4x4.5. Use your judgement.

• From the stock print head: The circuit board, the extruder, the stepper motor, the hotend fan, and the top cover

• A compatible part cooling fan cover, as the stock one will not work with this mod. I've designed one that can be used with both this mod and the original hotend.

• A short length (~10mm or so) of PTFE tube - standard 1.9mm or 2mm ID tubing, not "low friction" or star variants

• Tiny bit of superglue (optional but recommended, to hold the magnets in place)

• An Ender 3 style hotend with a silicone sock for the heat block. 50W heat element and standard NTC thermistor recommended. Heat element must be 24V.

• Soldering iron and associated gear (solder, heatshrink; as well as heated insert tips)

Print instructions:

Materials
Heat resistance is very important here. So the absolute bare minimum to use is ABS. If you are able to print this using PA-CF, or PC, or another material with especially high heat resistance - do so! DO NOT - I repeat, DO NOT - print this in PLA or PETG.

Print Settings
- In general - 0.2mm or smaller layers, print fairly slow, use Classic wall generator, use brims.
- Print all pieces as oriented in the STEP files.
- On the main part, there are three points on the back (see image below) where supports should be painted; the fill tool will mostly handle this, but you may want to use the Sphere tool in erase mode (shift+click) to remove some of the excess around the extruder motor. Tree Organic or Tree Hybrid recommended. Print with (at least) 3 wall loops.
- The fan cover consists of two files, which should be imported as parts of a single object; the inner part only should be printed with one wall loop, zero top/bottom layers, 15% or 20% infill, Rectilinear (not aligned) infill, and a very slow print speed (20mm/s or so). The outer part should be printed with normal settings. No supports are required.
- No special settings or supports are needed for the PTFE spacer.

Assembly instructions

Preparation

1. Disassemble your stock print head. You do not need to remove or replace the X carriage.

2. Solder the Ender 3 hotend's thermistor and heat element onto the connector from the stock print head. It is up to you whether you want to solder mid-wire or directly to the PCB, but pay careful attention to wire length. (I cannot advise you on the correct length, as I did not pay careful attention and was just lucky that they turned out close enough I could kind of curve them into fitting.)

3. If your heat block's silicone sock does not fully cover all four sides (exposed top is okay), cut a small piece off a second sock and use that to create a cover for as much as practical of the fourth side. You can make a small hole and thread the thermistor screw through it to help hold it in place. In particular it matters that the sides and back are covered; the front is less important.

4. Insert the PTFE spacer into the entry area of the hotend's heat sink, it doesn't matter which way up. Insert a PTFE tube through this, as far as it will go. Use a blade to mark the tube flush with the end of the spacer, remove the tube, cut it to this length.

5. Use a Phillips screwdriver to create an internal chamfer at the entrance of the PTFE tube.

6. Reinsert the PTFE tube (and the spacer that likely came out when you removed the tube).

7. If the wires for the heat element come straight out, you will need to bend them so that they instead go upwards.

8. Insert the heated inserts as per the image below. It is very important to get them properly level - use the trick of inserting 90% of the way then using a flat object to finish them off, and err on the low side temperature-wise for the ones with raised plastic rings around them. Note that not every hole has an insert.

1. Insert a 5x2mm magnet into each of the two magnet holes. Make sure to match the polarity of the original print head. Superglue is recommended to help hold them in place.

Assembly

1. Insert the hotend fan through the side (pass the wire through the hole first), with the label facing inwards. Secure it in place using the two long screws from the stock head. Run the wire through the wire channel.

2. Snap the hotend fan cover into place (insert the tabbed edges first), and use the countersunk screw from the stock cover to secure it.

3. Secure the hotend in place using two countersunk M3x18 screws. The thermistor and heat element wires should exit the block on the right hand side. Route these wires through the wire channel, with the more-rigid heat element wires on top.

4. Attach the stepper motor, using its original screws.

5. Attach the extruder, using its original screws.

6. Reconnect all cables to the PCB, then attach the PCB using two M3x6 screws.

7. Reattach the top cover with two M3x10 screws. You may need to remove the small plastic tabs (or you can print a replacement that doesn't have these in the first place).

Post-Assembly

1. Attach the new print head to the X carriage, using the original screws.

2. Reconnect the USB-C (or not, on newer 5X's) cable to the print head.

3. Before attempting any prints or calibrations, double check that the part cooling fan functions correctly when manually turned on.

4. As an extra safety check, if you have an enclosure, I recommend heat soaking it and see if the nozzle temperature reading corresponds with the chamber temperature as you'd normally expect it to. This is not practical for unenclosed printers.

5. Before attempting any prints, re-run bed levelling and extruder temperature calibration (or for Z-Mod users: redo bed mesh, PID tune extruder).

Enjoy your new hotend!