10.5 micron resolution?! – Longer Orange 4k 3D Printer Review

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🔸Longer Orange 4k: https://s.zbanx.com/r/T0kMSg7TlqFF
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🔸Longer Orange 30 3D Printer: https://s.zbanx.com/r/dIrS4EAvAGQq
🔸Longer LK4 Pro 3D Printer: https://s.zbanx.com/r/7QHMo5X6jffT

Video Transcript

Hey Everyone, and welcome back to Hoffman Engineering. Today we are going to take a look at the Longer Orange 4k, a resin 3d printer boasting an insane sub-pixel resolution for beautifully detailed prints. But does it deliver on those claims? Lets find out.

Before we begin, a quick disclaimer. This Longer Orange 4k was provided for review by my friends at Longer. If you like what you see in this video, you can find more information using the links in the description, and if you purchase anything using my affiliate links you’ll be helping support this channel. As always, my reviews are my honest opinions and experiences after using this machine over the last month. So lets get into the review.


The Longer Orange 4k is a resin-based LCD stereolithography (SLA) 3d printer. One of the key specs for LCD SLA printers is its pixel size. The size of the pixel determines how accurately the printer can cure the resin. The smaller the pixel size, the more detailed the prints can be.

It’s time to get technical. The Orange 4k has a 405nm UV LED panel, which shines through a 5.5 inch, 4k LCD screen with a resolution of 6480 by 3840 pixels. At that size, each pixel would have a side length of 31.5 microns. However, the Orange 4k has two variants; a “Color” version with a LCD screen with that 31.5 micron pixel resolution, and a “Mono” version with a LCD that splits a single pixel into 3 “subpixels”. That effectively gives the Mono version a Y resolution of 10.5 microns, while the X resolution remains at 31.5 microns. I have the Mono version with me today, so that is the version I’ll be reviewing.

The Longer Orange 4k has a print volume of 120mm x, 68mm y, and 190mm z. The bed itself has a sloped top surface, so excess resin drains off easily. 4 screws allow for bed leveling, and the bed is attached to the z-axis using a single thumb screw. The z-axis contains the threaded rod, and is supported by dual linear bearings that provides smooth and stable movement.

The Orange 4k uses the same resin vat as it’s little sister, the Longer Orange 30. I like the design of the plastic vat. It has an integrated scale which makes it easy to see how much resin you have remaining, and also helps not to overfill the tank and spill resin everywhere. The bottom of the vat is the standard FEP release film. That film does wear out over time, but a couple replacement sheets are included with the printer. The vats also come with a plastic cover to make storage easy.

The vat is placed over the LCD screen, and attached to the base with two thumbscrews. The base of the printer is full metal, which feels very sturdy. It has a 2.8 inch touchscreen on the front. It is a resistive touchscreen, so works well even when wearing gloves (or using a stylus). Using the touch screen, you can select files to print, or move the print bed, level the bed, or test out the LCD screen.

Prints are sent to the printer using the included 8gb USB stick on the right side, and the back contains the power switch, and the input for the 90W power brick. The printer has a removable orange acrylic cover, which filters out unwanted UV light.


The initial setup was a breeze. No assembly required, just unpack, level the bed, and print. Bed leveling was easy, unscrew the 4 screws on the bed so that it can move freely. Place a sheet of normal printer paper over the LCD, then lower the bed to its home position. Tighten the screws, and the bed is now leveled. Replace the resin vat, pour in some resin, and start printing! Longer does not include any resin with the printer, so you will need to purchase a bottle of resin separately before you can start to print. I have a feeling that might catch a few customers off guard, so be sure to buy some resin. While you are out, be sure you have plenty of nitrile gloves, isopropyl alcohol and paper towels on hand. With resin printing, you’ll need it. And be sure to subscribe to see an upcoming video on how I wash and cure my resin prints.


Before we can print, we first need to slice our models. The Longer Orange 4k has support for 3 slicers, Chitubox, Lychee, and their own slicer called Longerware.  Many resin printers are locked to a single supported slicer, so it’s good to see options here. Their own slicer Longerware worked fine, but its support generation options are a little limited. I ended up using Chitubox for most of my prints, since that was the slicer I was the most comfortable with. The included USB drive contained prebuilt profiles for a few different resin types and layer heights, and they all worked great. I didn’t need to adjust any exposure times, even with a variety of resins from different brands. The default profiles have exposure times of 1.5 seconds for 25 micron layers, 2 seconds for 50 microns, and 3 seconds for 100 micron layer heights. Between each layer the build plate is lifted, peeling the freshly cured layer off the bottom of the vat. That lifting time takes a few more seconds, resulting in about 5.5 seconds per layer overall. That is a pretty fast print speed compared to previous generations of resin printers, and are on par with other 4k printers in the same class.


Lets take a look at the prints. First up are the pre-sliced sample prints included on the USB stick. The vampire bust, three-wise-skulls, and the Longer coin all printed flawlessly. The layers are very consistent, even on the tall skull print. That shows that the dual-axis axis guides are doing their job of making the print bed very stable. The smooth curve of the cape of the Vampire Lord helps show off the high resolution of the LCD screen. Often curves like that would display pixelation from the display, but I cannot see any with my eyes. If you want to see details about each of the prints, you can check out my 3D Print Log profile also linked in the description.

Next is the Eiffel Tower. This highly detailed model has very intricate lattices, and the Orange 4k printed it perfectly. The extremely thin railing around the bottom platform is perfect, and moving on towards the top shows that even the small lattice were printed separately. This model always impresses me, and the Orange 4k pulled it off.

Maybe it pulled a little too well. This was printed with Elegoo Grey, which is a very beautiful but brittle resin. And I ended up chipping the corners of each of the feet when trying to pull the print from the bed. It adhered just a little too strong for this particular brand of resin, you might need to be more careful than I when removing prints (or add a raft in the slicer).

Longer claims the Orange 4k has 190mm of print height, so I’m definitely going to try all 190 millimeters. This lattice vase was scaled up to 190mm, and printed with 100 micron layers. It took 5 hours and 45 minutes to print, and it successfully printed all 190 millimeters. This model was sliced using the Longerware slicer. The slicer made a couple of mistakes, and made some parts of the inside solid where it shouldn’t be. Those few random layers show as lines on the outside. But, as we move up towards the top of the model, the lattice was printed nice and sturdy. There are no layer shifts to be seen, I am really impressed by the stability of the z-axis.

Each print tells the same story, the Longer Orange 4k produces very high-detailed prints. Whether you are printing a single small object at a time, or packing the build plate to the brim, it was a very consistent printer. Miniatures, dice, and even buff Pikachu’s didn’t phase this machine. It even handled multiple brands and colors of resins. I tried Elegoo Grey, Elegoo Clear, and Anycubic Grey with no issues. The resin vat was easy to clean with isopropyl alcohol, and made switching resins relatively easy. You could also purchase multiple vats and swap them out as needed.

I also had to test out the different layer heights. I printed The Joyful Yell model 3 times, with 25 microns, 50 microns, and 100 microns respectively. Even the 100 micron is very highly detailed, but if you zoom into the face you can see the individual layers with the right lighting. The 50 micron the layers are much less apparent, and at 25 microns they seemingly vanish. But the Orange 4k handled each setting perfectly, and the print times scaled as you would expect. The 100 micron version took exactly 2 hours to complete, the 50 micron doubled to 4 hours, and the 25 micron doubled again to 7 hours and 45 minutes. 


I did run into a couple of issues during my testing. My first two prints failed, the Three Wise Skulls pulled away from the print bed a few hours in each time. The poor adhesion was caused by me putting too much pressure pushing the build plate down when I first did the bed leveling, so the bed was too close to the screen. After re-leveling the bed, I had no more adhesion issues, and haven’t had to touch the bed leveling in the one hundred hours of printing since.

My other failures were due to support generation. I love the “fine” supports in Chitubox, as they are easy to remove and leave very little marks. But sometimes you need more support than that, and the print pulls away from the support mid-print. I don’t think its a flaw from the machine itself, its inherent to any resin printer with a peeling mechanism. I’d recommend adding a few “medium” supports to make sure the print will be well supported. Longer’s own slicer, Longerware, generated pretty sturdy and dense supports by default. They did their job, but left marks and missing pieces on some of the prints. You may want to try out the different slicers to find the one that works best for you.


Overall, the Longer Orange 4k is a very impressive medium-format resin printer. While I don’t have the lab equipment to confirm their 10.5 micron resolution claim, I found that the Orange 4k does print with incredible detail. The machine itself was easy to work with, it was quick to get to printing the first print, and it printed very reliably (as long as you have enough supports). I love having the option of multiple slicers, it means you can use the slicer that you want, without being locked into a specific one. And the same with the resin, you aren’t locked into their own brand of resin. Swapping resins was simple, and the design of the bed makes it easy to clean after finishing a print. Since the printer comes in two varieties, the “Color” and the upgraded “Mono” versions, I would recommend picking up the Mono version. It’s faster and more detailed, and seems to be more widely available. Longer also sells replacement parts, including the LCD screen, so it should be easy to maintain in the future.

The Longer Orange 4k Mono launched with an MSRP of $529 US dollars, but I am seeing frequent sales around the 400 US dollar price. At those prices, I can highly recommend this printer for those looking for high detailed 3d prints. Resin printing is substantially more work than filament 3d printing, but if the high-detail is worth the extra effort to you, the Longer Orange 4k makes resin printing as easy as possible.

So thank you all for watching my review of the Longer Orange 4k, and thank you Longer for providing a review printer for me to try out. You can find more information in the links in the description, and if you decide to purchase one using the affiliate links before, you’ll help support this channel. If you have any questions about the Longer Orange 4k, or any suggestions for topics I should cover next, please leave them in the comments below. And thank you all for watching, I’ll see you all next time.

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