A couple of months ago, Two Trees a Shenzhen 3D printer manufacturer reached out to me and asked me if I want to try out their new flagship 3D printer. I usually do not tend to do a lot of 3D printer reviews but this machine stood out due to a couple of reasons. A coreXY is nothing new, but other similarly prized competitors like the Ender 5 use the commonly known rollers for the axis, whereas the Sapphire Pro uses linear rails which should give the axes more rigidity. This allows faster print moves at higher quality and since I usually want my parts fast, this was totally what I was looking for. It also advertised silent stepper drivers for the X and Y axis which is always a bonus. Extruder and Z-Axis unfortunately only use good old Allegro A4988 drivers, probably to save cost. They are mounted on a Makerbase Robin Nano 32bit board and the whole system runs on 24V. The build area is advertised as 235mm in all dimensions but as it turns out, only around 220mm are usable due to clearances. Together with a sturdy frame, a Bondtech BMG style knock-off extruder and a 3.5” color touchscreen, this machine seemed to be a very competitive combo for around $320 with stock also available in the EU and US to avoid trouble and costs with customs. So, I decided to give it a try! If you have experience with this printer then please leave a comment down below and tell us what you think about it because my experience may differ, since I got one of the earlier machines.

Assembly was actually planned on a live stream but that didn’t work out, fortunately. Fortunately, because this was quite a frustrating process for me. It first started with a really bare-bones manual that I just was able to follow, but especially the wiring is nothing for a newbie. There is an assembly video around but that also doesn’t help that much more. The printer comes as a kit and requires roughly around 1 to 2h to put together if everything goes well. This includes assembling the top plate with the linear rails and the belt system that unfortunately lacks a proper tightening mechanism. Here, I unfortunately already hit two dead ends. At first, I noticed that the linear rails were loose and it turned out that on further inspections the screws they used were too long. They delivered M3x8mm screws that bottomed out whereas M3x6mm would have been necessary. Since I couldn’t get such short screws on short notice, I used my handy crimping tool, which is probably more designed for softer screws to cut the bolts to length so I could continue with the assembly process. The next problem directly occured when I wanted to screw everything down because the top plate was all bent and dented. Tightening everything down this way just resulted in the carriages binding up, so I tried my best and used vice clamps to bent everything back straight. This is something that should not happen and didn’t come from shipping because there everything was really well packed. So Two Trees, I hope you sort out this kind of quality control problems. Also, things like a way too long Bowden tube just complicate things for beginners. When fastening the linear rails, make sure they are parallel because otherwise your carriages will not run smoothly. So, I finished that, at which point I noticed that the upper mounts for the z-axis were missing as well. Designed my own, printed them out and a couple of hours later I was able to continue with the build. The rest of the build went smooth besides figuring out where every plug needs to go on the mainboard. Usually I despise these corrugated plastic hoses in which you put your wire harness, because they make your fingertips bleed when inserting the wires. This time though I printed myself a nice, handy tool that made the insertion process quite easily and honestly, in the end, the printer did look very clean. One thing that did bother me was that there is no strain relief for the heatbed, which is kind of dangerous and I do have to print me something as soon as possible!

All right, we have come that far, so how does it print? Well, not at all in the beginning. The reason for this is that the PID control values for the used 50W heater cartridge were so off, that the printer overshoot the desired temperatures by 40°C or more in the beginning and was not able to reach an equilibrium so that the machine never started printing. At first, I seriously waited more than 30 minutes, noting happened, only the temperatures oscillated. A connoisseur of 3D printers and a couple of G-code commands would now advice to do auto-PID tuning with M303. Well, that didn’t work because Marlin spits out an overtemperature warning due to the severe over-shoots. In the end I managed to reduce the first over-shoot in the process with blowing air on the heaterblock so that the process was able to finish. After that the temperatures were still not perfectly stable, but at least printing started at some point …. Until the machine lost steps on the x and y axis. Great. Well, turned out that the reference voltage of the TMC2208 was set way too high to around 2V instead of a reasonable 0.9V. Changed that and I was finally able start printing! I hope this is sorted out for current machines but you never know. In order to make this review as realistic as possible and not mod the whole thing spending again as much as the printer cost in the first place, I tried to test it as out-of-the-box as possible. The only things I did besides reference voltage and PID values were that I printed two new fan shrouds from PETG because the part cooling fans are horribly underpowered in the first place and the stock shrouds spread the air too widely. Then there is the homing switch that just touches the housing of the bearing and makes it really unreliable. Here I also printed a small clamp so that I get an even surface for the switch. Last but not least I added the new PID value in the firmware configuration file and also adjusted the stock print area parameters and maximum speeds, accelerations and jerk because they were more than conservative and slowed everything down. I linked the firmware files down below for everyone who wants to install them as well. The topic firmware is also a bit controversial, because Two Trees only provides the precompiled binary with the configuration file. Makerbase does provide a version of Marlin for their Robin Nano but considering the date probably not the latest release. So if you currently want to mod the firmware of your Sapphire pro you need some tinkering, but I linked a very useful guide down below.

Now, when it prints, it kind of does that very nicely. Look at those parts! I made myself a profile in PrusaSlicer that you can also download form my website that is linked below. Due to the rigidity of the linear rails you can go quite fast and accelerations also don’t need to be horribly low. To dampen the rattling frame, I usually have my printer on a big slab of concrete with some foam below it. You can’t imagine how much that isolates noise and vibrations! The parts show almost no ringing marks on the surface, which is pretty nice. You should only tighten the screw on the extruder slightly because otherwise it squeezes the material to the side and together but after a proper setup, I have to say that it does work quite well. The retraction torture test with the chainmail did work perfectly. I didn’t have a jam or something like that so far. The only thing is that the extruder is noisy due to the allegro driver that it uses. Also, the spoolholder on the side does it’s job well even though I thought it was too small in the beginning. Unfortunately, even with the new fan shrouds, the printer has a cooling issue what can especially be seen in some overhanging areas. This is definitely something I need to work on in the future if I want to print fast. And now to the elephant in the room that you might have already noticed on the previous shots. The printer unfortunately suffers from visible z-banding or wobbles. I checked the lead screw if it was straight and it was. I replaced the coupler for a test, didn’t change anything. I even printed a new lead screw nut out of IGUS polymer bearing material, which also didn’t change anything. So that’s kind of unfortunate and might require major upgrades either with the bearings and linear rods, or with a stepper motor that has an integrated leadscrew. The thing is that a slight wobble is visible on especially flat surfaces. Still, on most parts you have to look for it to notice it. So even though it’s not very pretty, I think this still might be okay for many because other than that, I really can’t complain about the print quality, if anything it’s really great!

The fake-tak build surface holds the parts very well, actually even too much up to the point that you sometimes break them while removing. This does allow it though that you can print PLA at 30°C on it and save energy that way. I’d probably ditch the print surface and use glass or some aftermarket flexible print plate system on it.

In terms of noise level, it could be way better that it currently is, because the printing noise itself is very low due to the TMC drivers besides the extruder. The thing that makes it quite a bit unpleasant is the fan of the powersupply that is clearly hearable even at minimal load and also the 30mm hotend fan is not the most pleasant. It’s not that bad and still better than a CR-10 for example. Still it bothers me a little when I’m working next to it and eliminates a bit the advantage of the stepper drivers.

So let’s get to the verdict. In my opinion the Two Trees Sapphire Pro is a project and not a tool. What I mean with that is that if you’re looking to a new printer that just works out of the box I think it’s not the right machine for you. If it is your first printer seriously think twice if you’re really into debugging a. Though, if you’re looking for a project to work on and tinker with that machine then the $320 that you currently get it for is not wasted. The Sapphire Pro delivers a nice frame especially with the linear rails but does require some upgrades to make it work really well. I want to mod this one that I can print really fast but you can also get acrylic panels for the Sapphire Pro and with a proper hotend, this might become a machine for some really technical material printing! You can always argue that you can get something better for cheaper but I think that this package has some potential, even though it’s not perfect. But what do you think? Leave your ideas and maybe even experience with this printer down in the comments to help out everyone else! Full disclosure, this printer was sent to me for free as a review unit. No money has exchanged hands and all the opinions are my own!

Firmware and configuration file

PrusaSlicer 2.1 Configuration File

Marlin Guide: https://escope.de/posts/sapphire-pro-marlin/

Assembly Video: https://www.youtube.com/watch?v=qldEfeEO18s

Do you want to buy this printer (affiliate links)

Gearbest(aff) - $299 with COUPON "C37C515ECB18D000": https://geni.us/Laf1Zq

Alibaba (aff): https://geni.us/WJRP

Aliexpress: https://geni.us/PNhw

AMAZON (aff): https://geni.us/8FrP7m

Printable upgrades:

Z-homing clip: https://www.thingiverse.com/thing:3937753

Z-axis bracket: https://www.thingiverse.com/thing:3937746

Harness Tool: https://www.thingiverse.com/thing:3916005

TR8x2 Lead Screw Nut: https://www.thingiverse.com/thing:3937757