Almost every fault we are called to is one of three things, all of which the owner could have caught in five minutes a week.
On Friday the machine was fine. By Monday the marks are grey where they used to be black, and the obvious conclusion is that something expensive has failed. It usually has not.
Across the machines we sell and service, the overwhelming majority of faults are three things, and all three are visible to the owner before they become a problem.
One: the lens window has clouded
Every mark produces a small amount of vapour and debris, and some of it settles on the protective window in front of the lens. It builds slowly. The beam has to pass through it, so the energy reaching your material drops. It drops gradually, which is exactly why it is missed.
The symptom is a mark that is fainter than it used to be at the same settings. The instinct is to turn the power up, and that is the wrong move: you are now pushing more energy through a dirty window, which heats it and can damage it permanently.
More power is the wrong fix: compensating for a dirty lens with more power turns a cheap problem into a dear one. A window is a cheap consumable. A damaged lens assembly is not, and the second is caused by ignoring the first.
Check it weekly. Hold it to the light and look for haze. Clean it properly with the correct solvent and a lens swab, never with a shirt, a tissue or a household cleaner.
The laser makers say the same. Epilog's cleaning instructions for its engravers warn that smoke, resin and other contaminants left to build up on the optics "reduce the available laser power and may cause damage to the lens". They also tell owners never to use isopropyl alcohol or hardware-grade acetone, because the impurities in them can damage the optics. Use the cleaner your machine's maker specifies.
Two: a connector has worked loose
Machines vibrate, get carried to sites, ride in vehicles and get set down on uneven benches. Connectors work loose. The classic symptom is intermittent: the machine is fine, then it is not, then it is fine again after somebody moves it.
Intermittent faults are the expensive ones because they are hard to reproduce in front of a technician. Once a month, with the machine off and unplugged, go along every connector and push it home. It takes two minutes and it removes an entire category of fault.
Three: dust and heat
A Nairobi workshop is dusty, and a machine that runs hot ages faster. Keep the vents clear, keep the extraction working, and do not sit the machine against a wall with no airflow behind it. If the fan sounds different, that is information.
Reading a bad mark
The mark itself tells you where to look, which is worth knowing before you call anyone:
- Faint but even: power reaching the material has dropped. Lens window first, then focus distance.
- Sharp in one area, faint in another: the item is not sitting flat, or focus is off across the field. Check the work, not the machine.
- Wavy or stepped edges: something is moving during the mark. The item, the bench, or a loose mount.
- Fine but wrong colour: settings, not a fault. Different batches of the same material behave differently, which is why a test piece comes first on every job.
- Nothing at all, suddenly: check the connectors before assuming the worst.
The fault that is not the machine
Worth saying plainly, because it accounts for a good share of call-outs: sometimes nothing has failed and the material has changed. A client sends a second batch of what is nominally the same tag, from a different supplier or a different production run, and the settings that were perfect last month now produce a grey, shallow mark.
Nothing is broken. The coating thickness or the alloy is different, and the machine is doing exactly what it is told. This is why a test piece from the actual batch matters more than any maintenance step in this article. It separates "my machine has a problem" from "my material has changed", and those two have completely different answers.
The routine, written down
Weekly, about fifteen minutes in all: inspect the lens window, clear the vents, wipe the work area. Monthly: check every connector, check extraction, look at the fan. Every job: mark a test piece first, on the same material as the run.
That last one is not maintenance, but it catches more problems than either of the others, because a test piece tells you the state of the whole system in ten seconds, before you have committed 2,000 items to it.
All of this is covered properly during machine training (free with a machine from us, KSh 10,000 per person on its own), and it is the part people skim because nothing is wrong yet. It is also the part that decides whether a 30W fiber marker costing KSh 290,000 is still earning 5 years from now. If you have not bought yet, the questions to ask a seller include who services it and where the spares are. This is why that matters.
Sources: Epilog Laser, cleaning the lens and mirrors (read 14 Oct 2026).
Common questions
How often should the lens window be cleaned?
Inspect weekly and clean when it looks hazy, which in a dusty workshop marking coated metals can be every 1 to 2 weeks. There is no fixed interval that suits every environment: a clean office and an open-air site produce very different rates of build-up. Looking is the routine; cleaning is what looking tells you to do.
Can I clean the lens with a normal cloth?
No. Household cloths and tissues leave fibres and micro-scratches, and household cleaners leave residue that bakes on under the beam. Use lens-grade swabs and the correct solvent. If you do not have them, leave it dirty and order them. A hazy window costs you some power; a scratched one costs you the part.
The mark is faint. Should I just increase the power?
Not before checking the lens and the focus distance. Raising power to compensate for a dirty window puts more heat into that window and can destroy it. Clean first, re-focus, then re-test at the original settings. If it is still faint after that, something has genuinely changed and it is worth a call.
Do you service machines bought elsewhere?
Where the machine is a type we know, yes. What matters is whether parts for it can be obtained. Some imported units use components with no supply route into the country, and no amount of skill fixes an unavailable part. Send the model and a photograph of the label before assuming either way.
