CNC router service signs: what to watch for

Most CNC router service signs are small changes your operators notice before anyone else: parts coming off a touch out of size, edges that used to be clean, a sound the gantry never made before, movement in an axis that used to feel solid, and alarms that pop up more often than they used to. Any one of those is a reason to book a service while the machine is still earning.

Below, those signs are sorted by how you notice them, with what usually sits behind each one.

Why do the signs come before the breakdown?

Because the parts that fail on a router mostly wear rather than snap. A drive pinion loses a little tooth profile every day. A belt stretches a fraction. A linear guide left short of grease starts to drag. None of that stops the machine on day one. It shows up first as a change in how the router cuts, sounds or feels, and only later as a stoppage.

The catch is that people get used to it. The operator who has run the same machine for three years hears the new rattle every day until it stops sounding new. So the most useful thing anyone in the workshop can do is notice the change, write it down and say so.

What will your operators see in the work?

The parts themselves are the most honest gauge you have. Look for:

• Sizes creeping. A cabinet side that used to measure spot on now comes off half a millimetre long, or holes for hardware sit slightly off their marks. If it is always the same axis, that narrows things down.
• Edges that have gone rough. Ripples, steps or a furry finish where you used to get a clean cut, with a sharp tool in the collet. That points at something loose or worn between the motor and the cutter, or at the spindle itself.
• Corners and curves out of shape. A circle that comes off slightly oval, or a square corner with a small flat or step on it. Those tend to show slack in a drive, because the axis lags when it changes direction.
• Depth that varies across the bed. A groove that is deeper at one end of the sheet than the other. That can be the bed, the Z axis or the material, and it is worth knowing which before you start shimming jobs to suit.
• Parts moving. If panels shift or small parts get thrown, that often points at vacuum rather than mechanics. Worn pods are one cause, and the vacuum pods I supply to fit SCM and Morbidelli routers have their own page.

What should you listen for?

Every machine has its normal sounds. The ones to report are the new ones:

• A knock or clunk when an axis changes direction. Often slack in the drive: a pinion, a rack, a pulley or a coupling.
• A grinding or scraping note as the gantry travels. Dry or dirty guides and carriages, or a bearing on its way out.
• A spindle that sounds rougher than it did. Listen as it runs up to speed and as it slows down. A change in pitch, a rumble or a whine that wasn't there is worth mentioning, especially if the spindle housing is also running warmer than usual.
• A squeal from a belt. A slipping or worn belt, or a pulley that has started to move on its shaft.
• The vacuum pump labouring. Louder, hotter or slower to pull down than it used to be.

Listen from the operator's position, with the guards on and the machine running normally.

What can you feel?

Some faults are easier to feel than to see. With the machine stopped and made safe the way your workshop does it, an operator who knows the router can often tell if something has changed:

• Slack in the head or the gantry. If there is movement where there used to be none, something in the drive or the guides has worn.
• Vibration felt through the floor or at the control desk while it cuts, where it used to be smooth.
• Heat where there wasn't any. A spindle or pump that is running hotter than it used to, or a hot smell after a normal shift.

Nobody needs to take a cover off to notice any of this. If it feels different, that is enough to mention it. Finding out why is my end of it.

What is the control trying to tell you?

The control is watching things nobody else can see. A few patterns are worth paying attention to:

• The same alarm, more often. One following error a month that clears on reset is easy to ignore. One a week, always on the same axis, is a warning. Drives raise those alarms when an axis can't keep up with where it was told to go, and that usually means something is getting tight, worn or loose.
• Homing that has got fussy. Needing two goes to home, or homing that takes longer than it did. That can be a sensor gathering dust, a cable starting to fail or a drive working harder than it should.
• Lubrication warnings. If your machine has an automatic lube system and it has started complaining, don't keep clearing the message. Ring me.
• A battery warning. Some machines keep their position with a backup battery. If that battery runs flat while the machine is switched off, the axes can lose their position and need referencing again.

Photograph the screen when an alarm appears, with the date. A run of photos showing the same code is the kind of record that makes a service visit go straight to the right place.

Are there signs you'll only find in the records?

Some reasons to book a service aren't faults at all:

• Nobody can remember the last one. If there is no record, assume it is overdue.
• The hours have gone up. A router that has moved to two shifts, or taken on a big contract, wears faster than the calendar suggests. The maker's manual gives an interval; your hours decide how quickly you reach it.
• The machine came to you second-hand. Whatever the last owner did or didn't do is now your problem. A service early on tells you where you stand.
• It has been moved, or it took a knock. A machine that has been relocated, or had a crash that didn't seem to do any harm, is worth checking before small problems grow.

Which CNC router service signs mean ring now?

A service is planned work on a machine that is running. Some signs mean you are past that point:

• An axis that refuses to move, or to home.
• A clunk or bang followed by parts coming out badly wrong.
• A spindle that is suddenly much louder, smells hot or won't reach speed.
• Burning smells from a cabinet, or the machine tripping its supply.
• Panels that won't hold, whatever you do with the pods.

Those want a breakdown repair, not a service slot in a few weeks. Stop the machine, keep notes of what happened, and ring.

What does a service do with these signs?

A service is where the signs you've written down get followed back to the part causing them. On a CNC machine service I go through the lubrication, an alignment check, the drive train, the electrical side, and the e-stops and guards. If the check shows the alignment is out, putting it right is a separate job, quoted on its own.

The service is £500. If it turns up a worn part, you see it and hear what it means before anything else happens, and you decide what to do while the router is still working. That is the whole point of acting on the signs: the repair is planned, not forced on you by a stoppage.

How do you keep track of the signs?

Make it simple enough that people actually do it. A sheet of paper on the side of the control desk works fine:

• Date, operator, and what was noticed, in their own words.
• Which axis or which part of the machine, if they know.
• Any alarm code, or a note that there's a photo on someone's phone.
• What job was running, and on what material.

Ask operators to add a line whenever something changes, however small. After a month you will see patterns you'd never spot from memory. Have it to hand when you ring.

Who should look at it?

Someone who knows the make. The makes I know best are SCM and Morbidelli: of my more than 17 years on CNC machines, seven were spent employed by SCM Group UK. I'm independent now and don't represent any manufacturer. On top of that, I sell Hua Hua machines and back them up, and other makes running a Syntec control are fine. If yours is something else, describe it on the phone. My about page says more about how I got here.

If your router is showing any of these signs, ring me on 07904 610916. Give me the machine's make and model, the symptoms and how long they've been going on. Or use the call-back form and I'll phone you.