What Was Happening
A customer in Battersea SW11 had built a Creality Ender 5 Plus and could complete small parts, but larger prints showed a slight lean and dimension drift as height increased. They noticed that components intended to mate together became inaccurate on taller sections, even when base layers started reasonably well.
The issue had been present since assembly and became obvious after several weeks of use. Bed levelling was repeated multiple times, but geometry drift remained. The customer needed reliable large-format results and asked for professional setup instead of spending more time adjusting slicer settings that were not solving the root issue.
Our Diagnosis
We began with frame geometry checks using square and diagonal comparison. One vertical section was out of square by just over one millimetre relative to the base. On a large build volume printer, this is enough to create visible error growth over height.
Next, we measured dual Z alignment at both ends of the X gantry and found a notable height mismatch between left and right sides. We inspected couplers and discovered one had early cracking and intermittent grip loss under movement load. That can cause subtle slip events that look random in print output.
We then reviewed belt tension, pulley lock points, and lead screw condition to ensure no secondary faults remained. Root cause was clear: frame squareness error, unsynchronised dual Z travel, and a coupler beginning to fail.
How We Fixed It
We corrected the frame first. Fasteners were loosened in sequence, the frame was squared at each junction, and then tightened in a controlled pattern to hold geometry. Corner and diagonal checks were repeated until alignment remained stable after tightening.
The faulty Z coupler was replaced, and both Z sides were synchronised so the gantry sat level across travel. Lead screws were cleaned and lubricated, then full movement checks were performed to verify smooth operation without binding. Belt and pulley points were adjusted and secured as preventative maintenance.
After mechanical correction, firmware and BLTouch mesh routines were updated and rerun. Z offset was tuned live during first-layer testing to ensure reliable contact across the larger plate area. We then ran a 200 mm validation tower and a dimensional test part that previously failed.
A short tutorial covered dual Z sync checks, signs of coupler wear, and practical setup habits for large-format jobs. This gave the customer a repeatable process to maintain stability between service visits.
The Result
Following setup, tall prints showed straighter walls and far better dimensional consistency from bottom to top. The previous drift pattern was removed, and the customer could complete large functional parts that matched tolerance requirements more closely. First-layer behaviour also improved because gantry geometry remained stable across the bed.
The full onsite service took 4 hours including diagnosis, mechanical correction, calibration, and tutorial handover. The customer gained both an accurate machine baseline and a clear maintenance routine for dual Z reliability.
We also documented a monthly validation print and measurement routine so the customer can spot dimensional drift before it affects paid project work. That single process makes future troubleshooting faster because quality changes can be compared against known baseline measurements.
Why This Happens
Large-format printers expose assembly inaccuracies quickly because geometric errors scale with build height. A small frame deviation that is hardly visible at low Z can become a clear lean or mismatch on tall parts. This leads many owners to chase slicer settings even though the fault is structural.
Dual Z designs add another dependency: both sides must travel in sync to keep the gantry level. If one side slips due to coupler wear or slight binding, layer positioning drifts across the build area. Until frame alignment and Z synchronisation are stable, software adjustments cannot reliably fix dimensional outcomes.
Local Help in Battersea SW11
We provide 3D printer setup and calibration in Battersea SW11 and across Greater London, including large-format Creality systems that need precise assembly and dual Z tuning. If your prints look acceptable at low height but drift on taller jobs, we can diagnose and correct the mechanical causes quickly. Setup is GBP 90, tutorial is GBP 90, and combined sessions are available when you want reliable machine setup plus confidence running larger prints yourself.
Prevention Tips
- Check frame squareness after initial assembly and again after the first few weeks of use.
- Verify dual Z alignment regularly, especially after manual gantry movement or transport.
- Inspect couplers for cracks, uneven grip, or unusual play before they fail during long jobs.
- Keep lead screws clean and lightly lubricated to minimise binding and periodic artefacts.
- Validate geometry with a standard tall test print monthly to catch drift early.