Taking Care of Your Pro 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 maintenance on a Pro model.

1. Video Guide

2. Pro 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. 

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 make sure the machine and its support table are stable.

2.2 Drive system: Drive Screws

Ball screws and lead screws are the most common drive system for milling machines. They are endless screws translating a circular movement to a linear movement, through a nut moving along the shaft.

Lead screws or ACME screws are cheaper and reliable but tend to have a problematic characteristic for CNC milling called 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.It results in a little desynchronisation between the machine’s theoretical coordinates and it’s actual position. A small difference, but still a problem when you want to do precision milling. 

Precision ball screws are an alternative to lead screws that have many advantages. They use pre-loaded nuts filled with ball bearings that keep a permanent contact with the shaft, avoiding any backlash, but also removing sliding friction thanks to their rolling nature, making them much more efficient than lead screws.This is why ball screws are commonly used on higher grade CNCs such as the Mekanika Pro and Fab.

Lastly, all drive screws must stay clean and lightly greased at all times. When needed, you can clean them with alcohol as suggested earlier, but then you must apply a new coat of grease.

Put a small knob of grease on the screw before and after the nut, and move the axis back and forth a few times to spread it. 

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

But be careful!

Never use oil based lubricants, such as classical WD40 as they’ll eventually evaporate and leave the drive system exposed, which will have it damaged.

2.3 Guiding system: Linear Rails

The higher grade of guiding systems are linear rails. Those are manufactured to be very precise, and their sliding blocks use ball bearings providing a smoother motion while being protected in an enclosure.

There are cylindrical (round) rails and prismatic rails (also called square or profile rails).

Cylindrical rails are reliable but considered less stiff than prismatic rails when under heavy load, which CNC milling is subject to. 

Sliding blocks on prismatic rails also have a larger contact surface proving extra stability.For those reasons, prismatic rails are also often preferred in CNC milling,and 

Just like the drive screws, the sliding blocks and rails must stay lightly greased to function properly. So you can clean the rails with clean rags when they need it, and then apply a new coat of grease.

Sliding blocks usually have a valve to inject grease inside using a grease gun and this is the optimal way to do it… But if you don’t have a grease gun, applying grease manually on the rail is also perfectly fine: put a knob of grease on the rails and then move the blocks back and forth a few times to fill them with grease too.

You can then remove the excess to avoid dust accumulation.

As said for the screws: always use lithium grease labeled for ball bearing, and never oil based lubricants such as classical WD40.