FLSUN S1: What You Need to Know, an In-Depth Review 

You and Angus are the only guys I trust for reviews. Another banger, as the kids like to say.

You are the gold standard for 3D printer reviews.

Brutally honest! I bought a Bambu X1C based on your review and have been really happy with it. My printer is a tool. I don’t want to have to mess with it to get good results. The X1C does that out of the box.

Seems like a cool printer, I really hope they watch your video and make modifications to improve their product. You'll find out if they're a good company or not based on how they respond to criticism. If they can't take criticism they'll never improve

For me the biggest red flag is the deception of flow rate. A company has to respect its customers.

I love delta printers, I made my own large format delta. 500mm bed, 1.5m tall. You think this thing is big, mine looks like a phone booth (I built an enclosure for it). Deltas can have a something that looks like VFAs, but they're not, they're delta artifacting, which is why those who know what they're doing, use 400 step motors and small pulleys. My delta uses awd (6 motors -- top and bottom) nema 17 400 step motors and 16t pulleys. The high step count eliminates the artificating, and you get parts that are actually as designed, however you can't get the 1m per sec moves to put on the box if you do that, I can push 600-800, because I use a 40v PSU (did the math -- and that is recommended max for my stepper combo). I can push accelerations, but to some degree it's a parlor trick. FL sun reps saw my delta on 3d printer builder groups and tried to get me to try theirs and make a video about it, why? Looks like they're after the specs not quality. Also knowing the math behind deltas, the delta print volume is a cylinder with a cone on top, to advertise max height as the tip top of the cone is SUPER deceptive, true build volume of a delta is the cylinder, you never factor that cone into it because trig computation there gets super sketchy. FL sun DO BETTER. I have the CPAP blower on my delta too, but mine is actually implemented with a true analog converter board, so you can dial in the amount of cooling you need and it actually isn't super loud when you do it right.

11:23 That test file makes me think of the Volkswagon diesel engine EPA debacle.

Fantastic deep dive review! Nice to see someone digging in on accuracy of parts off this machine

The quality and depth of your testing and analysis is outstanding. FLSun should be paying you for that! 👍😎

STOP making copies of a slicer that you just make worse compared to the open source, all for the sake of making it closed source. Especially if your version is buggy or not polished. Cmon now, no one like scuzzlords. Thanks for the review and all the effort of testing, was interesting to see.

in this era of stimulating short videos, I find your video/voice soothing and make me slow down a bit to re-enjoy a real, in-depth review, it almost remind me of the vibe of the good old days when MK3 just came out and the community is full of helpful people and everyone is trying their best to make this technology better

Great review! I like how thoroughly you test, how honest you are with full disclosure, and how you tell the facts as you discovered them. You are very fair to the manufacturer, listing the deficiencies you found, but with helpful suggestions about how they could be remedidated.

Appreciate the honest review. Refreshing to be honest.

As usual I’m impressed by the depth of comprehension you bring to the project. 👍

As always, love your content and your upfront honesty.

Now that's what I call a full honest review!

Great review. I would not be happy at all if I dropped $1500 and wound up with all of these shortcomings.

What an excellent independent review. Saves everyone time and money and enjoyable to watch.

Great review. I had no unanswered questions at the end.

I wonder if the engineers need external feedback to make the bosses listen.

Thank you for your work on reviewing this machine for us. Good job!

Thank you for being so thorough with your review.

Great review, pretty much covered all my questions

Gday James, I throughly enjoy watching good fair honest reviews that say it how it is, many thanks mate

Excellent review and insights! I watched this as soon as it popped up in my feed because I was curious about this printer and considered buying one. I’ll wait and keep using my X1 Carbon.

I watched your other video before this and I was intrigued, I love that you have been honest and true, don’t stop being you! It’s your review and your opinion they cannot say anything! Also a huge amount of respect to do this!

Amazing review... Thanks for your excellent review... Please stay safe and well ...

Good honest review James. Thanks

Every reviewer was dissapointed with that machine. Yours was the most gently worded out of the bunch. Botfarm comments show that they're really trying to capitalize on their investment, not really by improving their hardware/software. Classic corporate move.

Wow. Haven’t watched your channel in awhile and am not familiar with 3D printing but your review was excellent as usual. A lot of what you said went way over my head but I still picked up on some of it. Excellent presentation.

Finaly a propper review and not just a "Hey I unboxed this and printed the 8m benchy that is not comparable because it doesn't meet the speedboatrace rules but looks okish for the speed." A big thank you for that and especialy for your honest words. Sadly I'm not surprised they tried to change your script. Because ever since, their machines are great (hardware wise, not the software!), but the company itself is kinda dodgy. They don't just exaggerate their specs, they straigt up lie to the customer. When I saw that internal structure of the melt zone I immediately throw away my hopes of prrinting carbon filled material with the T1 I ordered. I assume it has the same structure. Maybe we will see an aftermarket upgrade for that. We'll see. Luckily I have a big Core-XY that can print carbon fiber without any problems. But the craziest thing I saw from them so far was the lottery they did via a facebook livestream. The smaler prices were drawed via a wheel of fortune, wich was kinda ok but prone to error, because they didn't use a service for that, but everyone hat to comment in the stream a special phrase and they handpicked them out which opens the possibility to overlook some. Afterwards the winner hat to send them an e-mail. So in theory others could have send e-mails as well to claim a prize. But the last and biggest price was the S1. And this drawing was totaly rigged and they didn't even try to hide it. Spontaniously they changed from the wheel of fortune to method I never saw anywhere before. Everyone had to post a special phrase again in the chat of the stream again. But you didn't get into a pool by doing that. They let everyone do it over a few minutes repeatedly because they would stop at an unknown time. They showed a mobile phone into the camera with the stream chat. And when they chose to stop the one at the top with the correct phrase would win the printer. But here it comes. There were.. I think it were around 1600 people, watching the stream. So the chat was flooded with posts. But on the phone where only shown posts of the same 3 (if I recall correctly) people. And everyone was complaining about that in the chat. Obviously they ignored it and the ones that were shown in the chat didn't say anything to that as well. A minute later the stream ended in a hurry. That being said, the T1 will be my third FLSUN printer, replacing my SR and I hope it will be just as great, because I realy loved the SR and it already has a new loving home. But the people behind FLSUN are the worst.

Excellent review!!

The best review I've seen about this printer, reviewers should learn from you.

Appreciate this review

Absolute fascinating presentation. I'm dazzled.

Awesome and interesting review of the S1! 😊🤘

Thank you. Love your content

Awesome very detailed review

Hi, u became my preferred youtuber even if I spend a lot of money buying tools being influenced by your videos😅. I think u r one of the few that give a honest review and that is brave. Bravo. Best regards from Florence Italia 😊

I LOVE honest evaluation of products - Good & Bad... It allows the prospective buyer to make a calculated purchase - THANKS

I'm so glad I found your video. I was seriously thinking about buying one of these based on the claims. You saved me from a lot of frustration and disappointment.

I love your reviews on various products. So much so, that, as soon as I could, I ordered the Qidi Q1 Pro, which arrived a couple of weeks ago. I'm still learning Fusion, I was pretty proficient with AutoCad LT, but Fusion is a mare. If ever you want to do some Fusion tutorials I'll be first in the queue. Thanks for the work you do putting the content out. 🏴󠁧󠁢󠁥󠁮󠁧󠁿🇬🇧🏴󠁧󠁢󠁥󠁮󠁧󠁿

Thank you for the review

I got a FLSUN SR for a song. Thankfully because I've done nothing but have to tinker with it. They haven't released their customized Marlin software going against the GPL license. Since they have released new model printers it seems they've abandoned it. Vendors like this are sure to fail.

Excellent Review. I can only hope that the the manufacturer uses the review process to improve vs market. Other's, like Qidi, did just that and earned considerable respect with a follow-up review that provided evidence of solutions to the identified problems.

Love the honesty❤

Thanks for the review , I trust your opinion %100

Great review

Excellent review

Great review.

Thank you for your honest review!! It’s nice to see someone who is honest and not giving fake hype like other RU-vidrs. I pre ordered printers before and I can tell you they shouldn’t be major issues like this in 2024 anymore. Yes it is nice to see company’s pushing the limits of printers but not at the cost of people’s hard earned money as guinea pigs. This is what beta testers are for. Thank you again for the review!!

This is an excellent review…just what I wanted to know!

What a great review.

Great analysis James. Thanks for the shoutout!

Thank you for a great review! I got the v400 on release and had mostly the same issues. Still I loved it (briefly). Just looking at the motion system running is hypnotic. Then I of course got the X1c and my deep feelings for the V400 just faded. It became an other dust collector that I finally some months ago convinced a friend to adopt…

When reviewers say the company sent me this printer to review and I was not paid one can conclude that the payment is the printer. With that said most reviewers do a good job with the reviews they do the Pros and Cons but when a company outright lies about its product that is unacceptable thanks for pointing them out and standing by your word for doing an honest review. Wonderful Video I am Subscribing.

Wow! Really thorough and honest review. Functional prints are really important to me. I enjoy tuning, but at this price level, they should really have more ready to go for the user as a baseline. It's a super impressive machine overall, but needs some work on the software side at least. I'm excited for the T1 though, which I think is a more reasonable option for most people. For now, I still have my sights set on a Qidi.

Awesome review. Would love to see a followup and check what flsun improved over time. Regarding the print issues, perhaps the closed-loop steppers contribute to some of them.

perfectly honnest revew 👏👏👏

Thanks. I feel your pain as teaching three-legged elephants to dance is not my cup of tea either. I'm looking for strength, accuracy, and functional parts printed with adequate speed. This is because my cad assemblies are typically prototypes of multi-element fitted parts which (in some cases) will be produced with hard tooling or cnc. I was impressed by your recent video on that subject.

Great review James. I was hoping this big boy would perform very well. Maybe this review will help make it a better machine. Having worked in manufacturing (Quality Assurance), I have seen deadlines, money woes, and the echo chamber effect cause teething problems in good basic designs.

That is one damn HUGE printer! Lots of attention given to this printer and understandable so but I think the better option for most people is the small T1. Hope to see a review on that T1 soon

Kudos to you do this in single shot and standing there for over an hour.

Now that is an honest review, I’d buy that printer if they make those improvements

Thanks again James for that test... I never understood the use of delta kinematics for anything precise, there is too much that can fail. Personally I was fed up with constant tinkering on early printers so I went to a Bambu P1P. And I received yesterday my new P1S+AMS, the previous one will be dedicated to PET-CF with a 0.6 nozzle. Cheers, Jean

Thanks for a real look at the S1. Seems like FLSUN has the hardware part down pat however they seem to be lacking when it comes to the software side. Good factual video.

I’ve never seen a review come out better than a bamboo lab Printer

Flsun is good at making filament dryers, I'm not surprised they integrated one into this printer.

I will stay with my Flashforge thanks, 1/3rd of the price and it is point and print. I have 1300 hours on mine. The build plate got replaced at 1250 hours and I put a 265 degrees C hot-end in it at that stage. For the rest I wipe the screws and rods down now and again, re-grease the with a Q tip dipped in light grease. Both the slicer and machine auto update. The default settings in the slicer work. The filament can be from anyone, no RFID tags. This is how printers should work in this day and age. Thanks for your review, it certainly assists with purchasing considerations.

nice free testing

Wow, this looks like a total disaster... everything from the software side, misleading marketing, to the print quality. Kinda shocked they released the machine in this state.

It's nice to see a few reviews of the S1 out now, but I can't justify the money or space. I'm hoping it bodes well for the T1 though. Hers's hoping for some reviews soon!

If you get the chance, id love to see you review the neckog injection molding machine.

I have no use for a 3d printer but I still enjoy these. Hopefully they take you constructive criticism to heart and work on the issues. 👍👍

Great indepth quality review, thanks. Even just hitting 40mm^3/s for a couple of inches of a print run is not the same as a sustained 40mm^3/s. These flow rate tests need to demonstrate sustained flow rates for nearly the entire width (or delth) of the bed.

I own a Bambulab (P1P to P1S to X1 (Should have bought the X1 the first time)) because I trusted your review of it (gotta thrust my fellow software engineers) and boy is it a game changer. I used to hate FDM printing so much that I switched to resin printing (after 10 years). I never thought I would go back, but when I saw the print quality of your parts with the Bambulab I was blown away. Seeing the quality of what you got with the FLSUN I would never buy it. It's like coming back to the old FDM days. Yeah ok, fail, but fail fast, but ideally it would not fail and got it right the first time. I had maybe 4-5 failures on the Bambulab but it was mostly my fault.

Thank you for a proper review on this printer! The other reviews I have seen are too kind. Especially with the marketing nonsense and poor print quality. I am surprised with the salmon skinning. Properly dialled in deltas can have unmatched print quality because it doesn’t have the same z-wobble to deal with. Perhaps they need to increase micro-stepping and slow it down a touch.

yay! new clough vid

Great review! Just wanted to add that 30-40 mm^3/s flow rates can definitely be achieved on bambulab machines using an aftermarket hotend. I use the often recommended aliexpress hotend for my P1S with a CHT style 0.4 and am able to push PLA at 34 mm^3/s.

8:00 Hot tip, I love ASA as much as the next guy, and have found that putting a layer of PETG down first saves the bed. Sticks amazingly well while printing, then separates from the PEI and ASA amazingly well. Can also do multiple layers, then iron them to remove bed imperfections and get a pretty good smooth first layer of ASA. Give it a crack ;)

This is a really cool review! I saw a couple of videos about this printer, but your video is so detailed! I miss the times of Ender 3 printer. When printer were about what they are advertised... But now, you have to divide everything by 10 = ) Even Bambu printers suffer from marketing. What to say about others? I personally do not like that speed hype. So I now I am going to your X1 review = ) They talk about those Bambu's so much and all talks about 'look at how my table is thaking'! And only 15mm3/s? I installed BeMeGe printable BMG clone and copper heatblock, and I have got 18mm3/s on PETG. On stock Ender 3. I did not install any high voltage motors like those benchy shaped speed community users. Just some direct mod and upgraded firmware, set accelerations to 3000mm/s2 and it prints less then 2 times slower then Bambu. So what you wanted from FLSUN? If Bambu is markting shaking head thingy? The whole insanity shaking idea is about 'shaking' the community and users. Before that most manufacturers just written large numbers, like 300 or 500 mm/s. But actual accelerations was not so high. But people believed those numbers. And even today they may look at numbers at this FLSUN printer display and believe, that it prints 1000mm/s. Bambu makes it too look fast. But I look at their PETG profiles. (the generic ones) and it's 150mm/s maximum. Only travel speed is 500 actually. And now they create printers with custom frames. I love Ender 3 design as you can fix tools and upgrades anywhere you want on the frame. And even replace parts, or repurpose them. There is a PET extruder model which made from old Ender 3. What will they do from modern Ender 3 V3 frame? Nothing I guess. But it's all an old mans mumbling. Nevermind = ) Anyway, good video! Thanks again. I am transitioning to X1 review. Hope it will be as detailed as this video.

I have the v400 and it seems that FLSUN products are older school in that respect - they require tinkering. the v400 is a constant battle to get good prints, where as the X1C is a very simple plug and play machine. Thanks for the review.

Dear James, try todo the delta calibration from klipper may be you can solve part of dimensional issue.

Thanks for this. I use to own a Hatchbox Alpha which was about the same size delta, HUGE. That's the problem with them. Core XY printers can reach the same speeds and are so much more compact. I think I had forgotten how big a 300d x 300 delta is. The 110 mm^3 flow rate had me tempted though. Now with seeing the CHT built in to the heat block and not an interchangeable nozzle, no thanks.

In with the first thumbs up! Your mention of being handed a "suggested script" reminds me of when I sent off to have our dog's DNA analyzed. In the form, they asked for both a photo, and what breed we were told the dog is. Um, no, that's not how this works! Glad to see that you feel the same.

Having worked at locations with some very interesting managerial approaches, I can imagine it looked something like this: Sales team: Hey, we want to hit XXXm/s Manager: Cool, no problem Manager: Hey team, we need to hit XXXm/s Hardware team: Uh, I'm not so sure about that Manager: well, we've already sold it Software team: Hmmmmmm... maybe we can do something about that.

I've had really good success removing stuck ASA with the help of a heat gun. If you heat up the ASA, then try to scrape it, it comes off way easier (sometimes it'll even curl on its own around the edges).

How is the quality of the wiring between the effector and the board? The effector wiring harness on the V400 is problematic. The wiring harness connects directly to the board using JST connectors, but after a few months of use, those connectors get pulled / stressed by the movement of the effector. This can lead to incorrect temperature readings, which can either throw an error or cause the hotend to heat up an extra 30-40 C. The FLsun Super Racer has a better design with less stress on the wiring harness but it has issues with its extruder. So I was curious if they've improved the wiring harness with the S1?

Haha, I saw FLSUN and for a second, though you might have moved to Florida for some reason or where visiting and were making a video series on the scorching sun here.

You should use the CNC kitchen flow test. It is much more accurate and independent from the acceleration.

Great Review with crystal clear transparency, thank you! I purchased the S1, also had it about 1 month. I have not had much time with the machine but can say your review is spot on. My print quality so far is good to ok but I have only printed with PLA. The slicer concerns you mentioned are all the same thoughts I had upon using the machine. I know FLSUN will update their slicing software although, I would rather use a 3rd party like Cura, which I use with the FLSUN V400 and have enjoyed the machine for 2 years now. Even with Cura, as one would expect, I had to create my own presets after dialing the V400 in. Has been great ever since! If a 3D printer brand makes their own machine and software, I would think they would have spot on print settings to choose from, and several, changing in speed and quality 🤷‍♂🤷‍♂ One last thing I will add is that the last run I had with the S1, the print detached and created a huge mess. Not a spaghetti mess, the nozzle melted to the print and created a funnel upward. The plastic was extruding upward into the printer head encasing the hot end along with wires. Now, this print was running at night, I woke to the machine sitting still with an error "Machine Stopped Abnormally" 👀 Sooooooo...... I am dealing with that at the moment. Contacted FLSUN a week ago asking their advice. They suggested I take it apart and send them pictures of the damage. They said they will replace any damaged parts free of charge. I finally had time today to dive into taking it apart, and that was not fun😒...... lol. Now that I am to the point of sending out pictures & showing what damage incurred, their website is down and emails are kicked back saying not delivered! Horrible start with the new machine, so hopefully it will be taken care of as they said it will be, when I was in contact with them. Time will tell... Not going to lie.. I wish I would have waited for your review.. I think I would have a Bambu sitting on the shelf, not the S1.

Great review. My experience of FLSun printers has been mixed and performance (quality, leveling etc) has degraded significantly over time. I wondered about this printer but for me it seems no competition at all for the P1S and X1C I use now. Zitty finish and incorrect dimensions are deal-breakers for aesthetic and functional prints respectively, for me Thanks!

Great video. I'd be interested to see how the new Prusa Pro HT90 does since it's also a Delta printer.

I have just started to watch this review but the first thing that sprung to mind when you spoke about the first layer crashing into the bed and not being able to alter the z offset enough is, why can’t you pre heat the nozzle do it expands before mesh levelling? Will this allow the hot end to expand before it measures. I thought that with any printer I have used it always heated both the nozzle and the bed before it went through any levelling process, auto or manual. Or am I missing something?

Gotta turn the temperature right up for high flow rates. I get 51mm³s out of my k2 pro out of a 0.6mm nozzle @ 260c with a cht style volcano nozzle. The filament temperature range on packs of filament ae often still speced for 50-100 mms. Try testing the flow rate whilst cranking the temperature 😁 I did start getting extruder skipping at 51mm³s but 49-50 is still great flow rate. In practice though I print at 230mms but use adaptive layers from 0.12 to 0.40. On the flow test it was getting up to 450ish mmms speed which just throws quality and accuracy in the toilet on such a huge bed slinger 😂

Software signing is a racket though. There should be a way to sign software without paying rent to some certificate authority indefinitely.

Good review, printer in beta...., I still don't understand why all brands release clones of slicers that already exist, they should put all their effort and release profiles for their printers with different nozzles, materials, quality.

I don't know about the price difference, but, that Prusa Pro looks *real* nice.

@Clough42 Do you know if the extruder feeding wheel is reinforced steel? or normal? These make a difference too for support abrassive filament. I think I do not saw any mention about these in FLSun S1 specs.

There's the SV08 printer that just came out that's a voron 2.4 clone but that's been plagued by delivery delays and catastrophic nozzle failures due to the proprietary design.