FLSun V400 Review

Hello 3D Printing Friends!

Hello, 3D Printing friends! Today we're going to get a look at the FLSun V400! It's a tall, fast Delta running Klipper!

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OK, so today we’re going to take a look at the FLSun V400. This is a fast Delta 3D printer, with some interesting features. Thanks to FLSun for sending this to me, so I could show it to you!

About the V400

OK. So let’s dive into the specs and talk a bit about the printer. First off, as you have probably noticed, this is a Delta printer. Delta printers are just tall by design, but wooo, is THIS one ever tall! With a spool of filament on top, it’s almost FOUR FEET TALL. And with the printer on the bench here, I have to reach way up and load the filament by feel.

Unlike a Cartesian-style printer, or a CoreXY printer, a Delta printer’s build envelope isn’t a rectangular prism, it’s a cylinder. So instead of three dimensions for the print volume, we only have two: Diameter and height. And the V400’s build volume is a cylinder 300 millimeters in diameter, and 410 millimeters tall.

At the bottom of that cylinder is a 5mm thick aluminum plate that can be heated up to 110˚C. It has a magnet on top, which holds onto a big spring steel sheet with a textured PEI print surface. Yes, there’s a big flex plate on this printer so removing prints from it is SUPER easy.

The bed is bolted in place, and has no adjustments. So the printer includes a bed probe that allows it to get a mesh — like a topographical map of the bed — so it knows where the high or low spots are, and it can compensate for that.

The three arms from the columns all meet at the end effector, and there’s a lot going on here. There’s a pair of parts cooling fans. There's a Volcano-style hot end, with a Bimetallic heat break, and it can raise the nozzle to a 300˚C max temperature. It also has a direct-drive extruder, which is kind of uncommon on a Delta.

It’s capable of printing PLA, PETG, TPU, ABS, Polycarbonate, and Nylon. I have personally printed PLA, PETG, and TPU with it, and I’ll show you some of those prints in a little bit.

And, perhaps most importantly, there are three LED strips to provide lighting, so you can easily see what’s happening down at the nozzle without having to break out a little flashlight.

Okay maybe the direct drive extruder is the most important thing happening on the End Effector, but I really dig the lighting.

Let’s see, what else…? Oh! Speaking of lighting, the FLSun logo up on the top lights up!

You can turn that on or off from the tethered seven-inch LCD touch screen. That screen is actually a tablet-like computer, and it’s running Klipper.

And Klipper is really the big story on this printer. A 3D printer’s firmware has to both PLAN when and where it’s going to be moving the nozzle, and then EXECUTE all those move commands at exactly the right moment.

Normally, both workloads are handled by the microcontroller on the printer’s main board, but Klipper splits that workload. So the part of Klipper running on the tablet is doing the heavy lifting and complex mathematics of planning out all the moves. And it sends the movement commands over to the microcontroller in the printer to actually carry out those instructions. That means the microcontroller only has to concentrate on controlling the motors and reading the sensors. And that may be how this printer is achieving its 400 millimeter per second speeds.

The touch interface is provided by KlipperScreen, and I find that it’s well laid out and easy to use.

The tablet is also running Mainsail and Moonraker, which provide a web browser interface for the V400. And that interface is chock full of information and controls. It feels like everything you could ever want to know about or control on the printer is in here somewhere. And that’s really appealing to my nerd side. At first glance, I think this could be overwhelming to a person who was just getting started in 3D printing. But it’s also very easy to condense the display, hiding controls you don’t often need to access, and that can reduce the sense of information overload.

The tablet has three USB ports on it. It’s connected to the V400 by a power cable and one USB port. The USB flash drive that comes with the printer occupies a second USB port. This is used for G-Code file storage, among other things. And if you want, you can plug a webcam in to the third USB port, to monitor the printer and make time lapses of prints.

Oh. On another note, while the printer DOES have a filament runout sensor, so it can let you know when you need to RUN OUT and get more, it does NOT have a power loss recovery feature. For me personally, that’s not a big deal. I haven’t had a huge amount of luck with the power loss recovery feature on other printers, so it’s not something I rely on to save the day if power goes out.


Putting the printer together isn’t DIFFICULT. But you DO need a LOT of room. In fact the box alone occupied the entire workbench. But really, assembling the printer isn’t hard. All the tools needed, are included. The manual is reasonably clear about the assembly steps.

But if you prefer an assembly video, the USB flash drive has a good one that goes through the whole process. And it has a rockin’ soundtrack. The flash drive also has videos for leveling the bed, getting your first print, getting the printer connected to your WiFi network, and even connecting a camera.

Printing the Pre-Sliced Models

OK. So I think that covers the Specs and the About This Printer stuff. I mentioned the printer’s 400 millimeter per second speeds a moment ago. So yes, this printer is fast. And having said that, this seems like the perfect time to talk about the things I printed.

First, I printed the four pre-sliced models that came on the flash drive with the printer.

This 20-millimeter by 20-millimeter by 20-millimeter CHEP Cube printed in seven minutes. SEVEN MINUTES! And for a seven-minute print, this is NOT BAD AT ALL.

Congratulations, Chuck Hellebuyck! Your calibration cube has hit the big time, and now it’s starting to show up as a test print that comes with a new printer!

About that, though - I think it would have been better if FLSun had left it named CHEPCube, instead of changing the name to XYZ 20mm Calibration Cube. Actually what would be REALLY nice would be if printer manufacturers included a text file with attribution for EVERY model they ship on the media with their printers.

OK. What’s next. Oh! The Knurled Nut and Bolt, which printed in just under two hours. It came out great, and the threaded parts work perfectly.

Next, there’s this …rabbit thing? It printed in 32 minutes. One thing I noticed is that the surface finish varies from glossy to satin, depending on how fast the printer was going on a given layer. The slicer slows it down to enforce a minimum layer time, and that gives each layer adequate time to cool before the next layer gets printed. But print speed can influence surface finish on some filaments. So that’s why that happened.

And the fourth and final pre-sliced model on the flash drive is this Overhang Test. This only took 23 minutes to print. I don’t see any real problems with this at all, and all the overhangs printed well.

Oh, all these test models were printed with Jessie PLA, from Printed Solid.

Slicing Models in Cura 5

FLSun includes configuration files for the V400 that can be installed into Cura 4 or Cura 5. And there’s a text file with instructions on where to copy these files.

One quick note about this if you’re using Cura on a Mac:

The instructions reference the share\cura\resources folder, and that’s specific to the Windows version of Cura. So the fastest & easiest way to get to that folder on a Mac is, when you’re in Cura, pull down the Help menu and select Show Configuration Folder. That’ll pop the folder open in the Finder, and you can see the Quality, Definitions, and Extruders folders in there.

You might have to make the Meshes folder yourself, if it’s not already there. So anyway, I copied the files into the right folders, and then added the V400 printer in Cura 5.

The printer configuration for the V400 only has one profile: NORMAL 0.2mm.

It works pretty well, but you may want to click the Custom button to adjust certain settings if want to print at a different layer height, or if you’re not getting good results. For instance, the profile has the nozzle temperature locked in at 210 degrees, and the bed’s at 60 degrees, no matter what material you’ve told Cura to use.

Clicking the little “Formula” icon next to these settings will tell Cura to use the material’s temperatures instead of the profile’s temperatures. You’ll have to set the bed’s temperature manually if you need something other than 60 degrees, though. Cura will let you save these changes as a new profile, so you won’t have to re-do them all the time.

Adding Thumbnails to Sliced Files

Cura has the ability to create thumbnails for your sliced files, and the printer has the ability to display them on the tablet when selecting a file to print, and while printing.

You can create the thumbnails by going to Extensions > Post Processing > Modify G-Code. In there, click the Add a script button, then click Create Thumbnail. Set the Width and Height both to 300. Then click the Close button.

Now, any model you slice will include a 300 x 300 pixel thumbnail embedded in the G-code.

Printing Files I Sliced

OK. So once I had Cura 5 set up for the V400, I wanted to slice and print some files of my own.

First, I wanted to see how fast it would print a CHEP cube that I sliced, compared to the one that was included on the flash drive. Well, the one I sliced took ELEVEN minutes instead of SEVEN. But that’s still a lot faster than printing with stock settings on other printers. And it looks a little bit better than the seven-minute edition, I think.

Next, I printed a CaliCat, and this only took 19 minutes. I’m used to this taking about an hour. I can’t find anything to complain about on this print.

The CHEP Cube and the CaliCat were both printed in that black Jessie PLA as well. But, I didn’t want to print exclusively in that one filament, so I loaded some green PolyTerra PLA.

Then I printed a 3DBenchy. It finished in 34 minutes. And it looked pretty good, but there’s a little loss of detail on the license plate on the back, and the Z seam is pretty visible.

Next up is this Hex Pattern Bed Scraper. It only took 38 minutes, and I have zero complaints about it. I like this for scraping the priming lines and skirts off the bed, without scratching it.

Then I sliced and printed this Snap Closed Tool Box, and that took 3 hours, 14 minutes to print. This is has print-in-place hinges, and has a spot for the flush cutters, hex wrenches, and some of the other tools and accessories that come with the printer. The hinges feel a bit tight, but work fine. The outside looks a little rough in some spots, but overall it’s pretty good.

My last print with the PolyTerra was my Desktop Trash Can, but scaled to 200% size. This model is designed to print in spiral vase mode, but I wanted it to be more than just one wall thick. So I used what I call “Fake Vase Mode,” slicing it with no top layers, no infill, and I think 3 walls. It’s nice and strong, large enough to use as a regular desk-side trash can, and only took two hours and 23 minutes to print.

Then, I switched over to some PETG, in the form of Jessie PETG, in the Tree Green color. And I printed GreenGate3D’s bottle opener in 20 minutes. This was sliced with 6 walls and 50% infill, for super strength. Unlike a lot of bottle opener prints, this one doesn’t require a coin or other bit of metal. It’s more than up to the task of removing the lid from a bottle of Coke. This is also the only non-free model in this video, but it’s only 99¢. Probably one of the best dollars I ever spent on a model.

And then I printed this Herringbone Planetary Gear in 45 minutes. This is another model with moving parts that prints in place. It’s one I found fascinating to print back when I first started 3D printing, and I thought it was time to print it again. Two of the planetary gears were stuck a little bit on the outer ring, but with a little pressure, they popped loose, and now this thing spins great!

This final print is a multi-part model, and I printed the parts in different materials. This is a fun one. It’s a Squeeze Fan, and it works by squeezing this handle to move a set of gears to turn the blades to blow some air.

I printed the body in that green PETG, and most of the gears in this copper silk PLA. Silk PLA is kind of notorious for not having good layer adhesion, so the one gear that connects the rest of the gears to the fan blades, I had to reprint in regular PLA after I broke it. But the other gears don’t have that shear stress of having the fan attached to them, so they work fine.

Oh, and the fan blade part? That’s printed in TPU. I felt like that would make it safer if someone decided to stick their finger in the blades. Plus it was a great excuse to print in TPU.

Anyway, this little fan actually works. It doesn’t move a TON of air, but it moves enough that you can feel it. It's a little loud, though.

Wrapping Up - Likes and Dislikes

OK. It’s time to start wrapping this up. Let me go over some of the things I like, and things I don’t like about the printer.

First, the things I don’t like.

On the FLSun Super Racer, there was a tool drawer in the base, and that was super convenient for storing all the tools and accessories that came with the printer. The V400 doesn’t have that.

Um… It’s tall? I mean I don’t hate it because it’s tall. That’s just how Delta printers are designed. It’s like complaining that a unicycle only has one wheel. You kind of know that going into it.

Cura profiles. It would be great if FLSun had more than just the one 0.2mm - Normal profile available for the printer. And, it would be great if the profiles used the nozzle and bed temperatures defined in the material profiles, instead of being locked at 210 degrees for the nozzle and 60 degrees for the bed.

Also, even though the nozzle and bed can reach the temperatures needed for printing Polycarbonate and Nylon, those materials, as I understand it, print best in a heated enclosed chamber, and this is not that.

OK. Now it’s time for the stuff I do like.

This is a big, fast printer. And it can print big things. Also, it can print fast.

It’s a Delta, and those are just fun to watch.

I like the lighting on the end effector, I like the user interface on the touch screen, I like the web interface, and I like that flex plate on the bed, because it makes it easy to remove the prints.

It’s not super loud, either. The fans aren’t obnoxious, and the motion system is quiet.


So, that’s the FLSun V400.

It’s tall, it’s fast, and it’s done a pretty good job with the things I’ve thrown at it. There’s not a lot that I dislike about it, and in fact I’m genuinely impressed with its performance. On FLSun’s site, the V400 is $849 US on pre-order, and to me, that’s a good price for the feature set.

I’d like to thank FLSun again for sending this over so I could show it to you.

Below, you’ll find links to all the models I sliced and printed, as well as links to the printer itself if you’re interested in it.

Well, 3D Printing Friends, that’s about all the time we have for this episode. And now that we’re at the end, let's go print something cool!


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I sometimes receive compensation such as discounted or free products, and when applicable, this is disclosed in videos and their descriptions. Whether free, discounted, or paid full price, any reviewed product is tested to the best of my ability, and I give my honest impression. All opinions expressed are my own.