Taking Care of Your Evo CNC Milling Machine

Maintenance is mandatory to optimize the precision, efficiency and durability of your machine.

We recommend checking our video presenting the maintenance of all kind of CNC machines, but you can find below the details concerning Evo maintenance.

1. Video Guide

2. Evo Maintenance Advices

2.1 Daily Maintenance of a CNC

First of all, keeping your CNC clean of milling dust and chips is the easiest way to help it stay in good working condition. Dust will accumulate over time, and that can induce a loss in mechanical precision so cleaning it after each milling session is a must.The greased parts will tend to accumulate dust regardless, so once in a while you can do a deep clean of all those parts, but remember that you’ll need to apply a new coat of grease before using your machine again… We’ll explain this more in depth in the next chapters.

Talking about dust, a reminder that electronic boxes should be protected from dust as much as possible as you should not open them, unless your warranty allows you to do so and that you know what you are doing.

On Mekanika machines, the control units have a filter on the fan, to help protect it, which can easily be removed and cleaned without opening the box.

Once in a while, check the cable runs and the sensors of your machine. Make sure the cables haven’t been pinched or damaged and that sensors are working properly by checking their connection and testing them manually. 

If your Mekanika Evo sensors’ connections are too loose, you can press a bit their connectors with pliers to make them tighter.

Vibrations might loosen some screws over long periods of time, so once in a while, make sure the whole machine is tightened. It is possible to add a threadlocker adhesive to all the screws to avoid this problem, but it can make your life harder if you need to replace a part in the future… So the choice is yours.

And another important point is the machine’s stability: so adjust the levelling feet, until it is perfectly stable. 

2.2 Drive system: Timing Belts

Timing belts are often used for lighter CNC applications like 3D printing and laser cutting, but with a proper setup they are definitely able to handle milling too. They are perfect to allow an entry into the CNC milling world without the high costs of more advanced drive systems.

Belts and pulleys are open to external conditions, so you should regularly check their integrity and soiling. Inspect them and remove any residues that might be stuck inside their grooves and on both belts faces.

To work properly, a belt must be in tension. If they are too loose they might skip some steps when running; but if they are too tight, they will prevent smooth movement and wear out prematurely.

On a Meknaika Evo, you can adjust the belts tension by pulling them with a finger as much as possible. Those belts are very stiff so it is highly unlikely that you will be able to overtension them by hand. 

If you want to go more in depth and study the effects of different belt tensions on your milling results, you would need a tensiometer to run some tests and to find the sweet spot for your machine. I’ll put a link in the description to an open source 3D printable tensiometer model if you are interested. 

Remember that changes in belt's tensions might require you to run a new calibration procedure afterwards.

2.3 Guiding system: Guided Wheels and Rails

Wheels guided by grooves or rails are common in CNC guiding systems. They are inexpensive but they are exposed to dirt accumulation, so maintenance is very important on those systems, to keep the precision rate high.

The contact surfaces of both wheels and guides need to be clean and dry at all times. 
Remove any residue or irregularities that might alter the movement of the chariots, without forgetting the wheels underneath the profiles.

The pressure applied by the wheels on the rails must be checked too.

Turn off your machine, and try pushing the carriages:

When pushing carriages along their axis: they should move easily, without any resistance or jerking: if it is hard to move, the wheels are probably too tight.

When pushing the carriages out of their moving axis: you should not feel too much movement. If you can feel a wobble, the wheels are probably too loose. 

I you see some corrections are needed on an axis, check the wheels one by one as they are not always all requiring a correction:

Each wheel has an eccentric nut to set their pressure. Check a wheel by trying to spin it with a finger: if it is free-running, turn its nut clockwise to tighten it until it engages the rail.
Turn it the other way around if it blocks the carriage.

2.4 Lead screw on Z axis

Lead screws are endless screws translating a circular movement to a linear movement, through a nut moving along the axis. 

Lead screws are reliable but they introduce a problematic event for CNC milling called the backlash:

By design, there must be a bit of free space between the nut’s and the shaft’s grooves, otherwise friction would prevent the movement.So when the shaft pushes the nut in a direction, and then stops and goes the opposite way, the shaft will move without pushing the nut until it has covered that little distance.

Backlash is that little distance, in which the motor and shaft spin but the nut doesn’t move.

On Mekanika Evo, the Z axis lead screw is equipped with an anti-backlash nut.

This helps to keep both sides of the grooves in contact.

Make sure it is slightly in tension by tightening the small tensioning screw, but don't overdo it: it should not constrain the movement. 

Lastly, CNC drive screws must stay permanently greased. If you deep clean your machine, make sure you apply grease on it again, before using the machine.

You can use any brand of grease labeled for ball bearings, preferably lithium grease.

Be careful! Don’t use oil lubricants such as classical WD40 as they’ll eventually evaporate and let the drive system exposed.