I saw the price and the specs and thought: another standard 200-euro printer. I was wrong. In March 2021 I reviewed the Longer LK4 Pro, a budget machine that printed an 18-hour vampire castle and a support-free Mandalorian like a pro.
Unboxing and first impressions
I reached out to Longer and they kindly sent me a sample. It was packed very well, with rubber protecting every corner. It comes about 70% assembled, and it took me 30 to 45 minutes to put together. Easy enough for someone who has no idea how a 3D printer works.
For under 230 euros at the time, you get a very strong frame and a 220 × 220 × 250 mm build volume. The colour touchscreen is one of the best I'd seen, unique and very user-friendly. The heated bed is glass on one side and textured on the other. I used the glass side: easy to clean and prints stuck well.
It runs on 24 V rather than the 12 V of many printers in its class, so it heats up and starts printing faster. There's no auto bed levelling, but manual levelling is easy. Two features I loved: a filament runout sensor and power-loss recovery. Where I lived the electricity came and went, and more than once I came back to a paused print that resumed without problems.
There was no Longer profile in Cura, but I found out the LK4 Pro is a clone of the Alfawise U30 Pro. I used that profile and it worked from the first print.
Fixing the cooling and pushing it hard
The pre-sliced files on the SD card (a fox and a Shaolin monk, with a weirdly heavy ~60% infill) came out fine, but I noticed cooling issues, clearly visible on my first Benchy even with the fan at 100%. I printed a new fan duct in PETG that blows straight onto the nozzle, without the original gap in the middle. The next Benchy had no problem at all.
Then I tested it: a door stopper in cheap knock-off PETG (okay, actually good), an 18-hour vampire castle that came out amazing, low-poly vases in vase mode at 30 mm/s, a Halloween lolly container and pen holders for my kids. The final boss was a no-support Mandalorian in olive silk: 19 hours at 0.15 mm, and instead of spaghetti I woke up to a beautiful, detailed model with no stringing. I also finished the "Prinception" desk box, printed fast in draft at 0.3 mm, to go with the nozzle I'd made in gold silk.
What I didn't like
- Underpowered extruder. I'd have preferred a geared, ideally dual-gear extruder. It could cause skipping or under-extrusion, though I had no issues.
- A very loud fan underneath. A real pity, given the silent stepper drivers. Hard to film, study or work next to it. People fix it with a larger fan for a few euros.
- Cheap-looking plastic around the wiring, on an otherwise solid printer.
My upgrades
Four small prints: the PETG fan duct, a clip holding the Bowden tube and wires so they don't wobble, a filament guide so the filament doesn't bend and break, and a rear guide into the extruder. The cons can all be fixed with very little effort.