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Jun 08, 2017, 07:34 PM
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Tronxy X-3 & FLSun - i3 clone 3D Printers

I've started building a FLSun i3 clone and must say I'm impressed with the components they chose to put in this kit. It is a kit and will require some time to assemble. But, it has some great features and you'll end up with an i3 clone comparable to $300 printers that have been upgraded with $200 worth of parts. Some of the features that jumped out at me just looking through the box include:
- Z leadscrews with 4 starts/lands
- Flexible Z leadscrew couplings
- 2 nozzles .4mm ea
- Full Bowden Tube setup
- Smooth idler pulleys
- There's only 4 linear bearings (Y carriage)
- Build plate sub-base seems fairly substantial
- Came with 3 micro limit switches and a proximity sensor (bed leveling?)
- SD card with assembly manual, user manual, test files etc.
- Includes both European and US AC plugs.

A few of the cons are:
- Definitely a kit build and will take some time
- Control Panel wiring could be a bit messy if you let it
- Aluminum rails need a good washing to get the machining dust off
- Have to install software, but includes lots of instructions and videos

Be sure and watch the videos during the build, the fastener sizes shown in red on the videos are a lot more accurate than the manual pdf.

The default psu voltage is set to 220v, be sure and select 110v on the side of the psu.

Here's assembly video #1, the rest will follow it.
FLSUN 3d Printer Prusa I3 C Assembly 1 (15 min 31 sec)

Here's a video on FLSun mods.
FLSun i3 (prusa) 3d Printer - build and first mods experience (19 min 10 sec)

Low profile heatsink fan shroud:

"Radial Fan Fang" Parts cooling fan:

X-axis with integrated belt tensioner:

X-axis motor bracket block with integrated belt tensioner:

Z-axis leadscrew de-couplers:

Gantry braces:

2020 Filament spool holder:
(Taulman version):

2020 FIlament guide:

2020 extrusion cable clips:

2020 Extrusion Endcaps:

Build Changes:
- #6 size Finishing Washers added above and below bed springs.
- M3 washers and Lock Nuts added to bed leveling screws below the bed.
- M3 Lock Nuts (w/ M3-16) used as spacer standoffs between back of mobo and plexi plate.

OEM Boards:
- PSU model S-240-12, 12V, 20A, PCB 0360A-V02, A20112
- Mobo MKS Gen_L V1.0, Makerbase
- LCD REPRAP 2004A with full sized SD card reader

All steppers motors are 5mm shafts, Leadscrews are 8mm. The Z flex couplings uses set screws which is not as desirable as offset bolts that pinch, replacements would have to have a 5mm to 8mm transition.

There seems to be 2 variants of X carriage configurations. One uses 20x20 extruded aluminum channel and the other dual round rods. The one I have is the 20x20 channel version.

Print Quality troubleshooting:

- Hobby King Tronxy X-3
Last edited by jwellsy; Aug 02, 2017 at 05:36 PM. Reason: Add Tronxy Reference
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Jul 05, 2017, 06:24 PM
Registered User
Here are some more comments based on my assembly and the videos:
1) The Y tensioner should have a nut added
2) I did not have enought M3x25mm bolts (1 short)
3) The M3 x 30mm bolts were not labeled.
4) In the video (especially video 5) some parts are installed differently than in prior videos.
For example, the Z motors are on the opposite side as from the beginning.
the X motor and assembly are on the opposite side on the frame (turned around).
5) When installing the controller board, use a spacer between the circuit board and plexi-glass so the circuit board does not flex.
6) My kit came with 3 max switches AND a proximity sensor. The manual and videos do not mention this sensor. At this point I am not sure how to install it.
7) My X-Carriage pully holes are slightly off causing a lot of play on the extruder (3-4mm). Support is sending me a new piece. Hopefully that resolves this issues.

After contacting support, they provided me with updated files, specifically the assembly manual:
we have put all the instruction files in the SD card, please check it, if you can't read it, you also could download them from the link:
you can also find the assembly video on YouTube:
Attention!! the board connection refer to the link:
Attention!! please refer to the newest assembly instruction file:

Also Thingiverse has a forum group for this printer available here:
(Thanks Chris!)

Will add more comments by editing this post, as I finish this build..

Last edited by jlewis99; Jul 14, 2017 at 11:03 AM.
Jul 10, 2017, 02:21 PM
Registered User
I'm still building mine too. I mounted the prox sensor bracket between the nozzle cooler fan and the fan mounting plate. I don't think you can use the Z limit switch and the prox sensor at the same time, so the prox sensor plugs into the Z limit switch connector on the mobo. My sensor is on the opposite side from where the X stepper motor is.

I gave up on the manual and have mounted stuff where I thought it should go. I'm printing brackets and braces to stiffen it up.

I didn't like the OEM main power cord. It was only a two wire cord smaller diameter than the heater leads. I went to Lowes and got a 15' 14gauge grounded extension cord, cut the female end off and installed it instead. I feel much better having a grounded system.

Also, my Z screws didn't hang parallel to the Z rails. So I replaced the black spacers on the Z rollers with nylon bushings from ServoCity.
.194"ID x .375"OD x .312"L and they fit perfect. It also made plenty of thread to use M5 Lock Nuts.

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Jul 19, 2017, 01:14 PM
Registered User
Here's my FLSun layout.
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Jul 21, 2017, 11:15 AM
Registered User
I also added rubber feet. These are .75" table leg caps. Had to cut a notch part way down for them to fit. These feet really anchor the printer down.

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Jul 21, 2017, 08:12 PM
Registered User
I finished the build getting everything squared up and torqued down today. I've got everything moving the right direction and the heaters held temp fine once they stabilized. I've got the limit switches set and bed leveled. I should run my first test print Monday.

The control panel has a very basic/limited OS, so I'll upgrade to a better Marlin. Besides I want to get into the config H file and enable auto bed leveling.

Another upgrade I want to do is add a power On/Off switch or use a UPS.

I've been doing most of my printing without the part cooling fan running, so I'll wait till I need additional cooling to install that fan.

So far, with all the bracing and mods I did during the build this is turning into a pretty sweet machine. I wouldn't recommend this as some ones first 3D printer, but if some one is already 3D printer literate and can figure out what's important then this is a great value for a second printer.
Last edited by jwellsy; Jul 21, 2017 at 08:32 PM.
Jul 21, 2017, 08:31 PM
Registered User
Jul 22, 2017, 01:03 PM
dll932's Avatar
I heard a lot of good things about this printer. I'm interested to see how it goes for you all.
Aug 02, 2017, 05:34 PM
Registered User
Hobby King has just put out essentially the same kit as the FLSun called a Tronxy X-3. The only difference that I can see is that the HK unit has all the electronics inside a housing.
Aug 02, 2017, 07:30 PM
Registered User

Firmware Update Success !

I just had a big time breakthrough in being able to update firmware.

I could connect and control the printer with both Repetier and Simpilfy3D. Marlin would compile OK. But, when trying to upload Marlin with Arduino, AVRdude kept failing on COM5. Even though everything else was set on COM3, apparently AVR tries to auto switch to another COM looking for a good connection till it times out and fails.

The hint to fixing it was in Arduino\File\Preferences at the bottom it says:
More preferences can be edited directly in the file
C:\Users\user name\AppData\Local\Arduino15\preferences.txt

In that preferences.txt file another baud rate is defined. I changed/saved it to match the baudrate Repetier and Simplify3D were successfully using.

Then I went back to Arduino, hit upload and Marlin compiled and uploaded.

I am so happy, I've been trying to figure this out for a long long time. I can finally experiment with Configuration H changes, maybe even Auto Bed Leveling.

Maybe this will help someone else out.

Hurray For ME!!!!!
Aug 03, 2017, 12:40 AM
Registered User


I'm still waiting for my part. I printed a replacement but not sure I'd trust an x carriage in plastic with the extruder mounted to it 😀
Aug 03, 2017, 06:26 AM
Registered User
Originally Posted by jlewis99
I'm still waiting for my part. I printed a replacement but not sure I'd trust an x carriage in plastic with the extruder mounted to it 😀
I have a PLA X-carriage on my Malyan M150 printer, no problem.
Aug 03, 2017, 06:58 AM
Registered User
Here's an unpacking and quick build of the Tronxy. The guy gets frustrated because rushing through the build didn't produce the results expected. This is why I've kept stressing this is a basic kit build and not a good choice for a first printer.

There's an old saying that, you can't tell what's wrong if you don't know what's right. If you take the elements in the kit, take your time with the build and fix the issues along the way you can wind up with a decent printer.

One thing I didn't like about that Tronxy is that wonky Y carriage. I would replace that subplate and single rail setup.

This 3d Printer kit isn't so great. (17 min 6 sec)
Aug 15, 2017, 01:01 AM
Registered User
Originally Posted by jwellsy
Here's an unpacking and quick build of the Tronxy. The guy gets frustrated because rushing through the build didn't produce the results expected. This is why I've kept stressing this is a basic kit build and not a good choice for a first printer.
That guy has plenty of experience with 3d printers. If he says its not such a great printer ......
He did like the cheaper X1

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