3D printing tolerances

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3D printing tolerances
Dec192018

3D printing tolerances

3D printing is not a perfect process. As in any other manufacturing system, there are differences between what we design and the physical object we manufacture. These small differences between the computer and the real world are called tolerances.

Obtaining a tolerance 0 in the physical world is impossible, that is why there are certain tolerance values ​​that are acceptable and do not affect the functioning of the designed piece. Knowing the acceptable tolerances for each application as well as the tolerances with which your 3D printer prints marks the difference between a successful print and a failure.

That is why in this article we will see how to measure the tolerances of your 3D printer and how to design with those values ​​in mind.

How tolerances affect your 3D impressions

Knowing the tolerances with which your 3D printer can print is essential if you are going to design pieces that interact with each other. When you know these values ​​it is much easier to design with enough slack so that all the parties behave as you want.

In previous articles we have given you a basic design guide to leave the necessary slack according to the behavior of the different pieces. You can see it in the following image.

Clearances for 3D printing

When you know the tolerances of your printer you can adjust these clearances to improve the functioning of the different parts that make up your design.

How to measure the tolerances of your 3D printer

The first thing is to calibrate your printer correctly. In commercial printers this step is usually not necessary, but in the assembly kits is essential. For this, it is best to perform a calibration cube and adjust the steps of the motors until the accuracy of the machine is correct. There are hundreds of models on the internet to perform this step. We recommend you use the following:

3d printer calibration cube

3D model of calibration cube

It is also important to calibrate the 3D printer extruder and make sure that the amount of extruded material is correct.

Once we have the calibrated machine we will go to measure the tolerances of our machine. For this we will print 5 pieces of the following model, in separate prints.

Model to measure tolerances

Once the 5 pieces are printed, always take measurements in the same part and with the same orientation of the piece. By subtracting the upper and lower value you can know the tolerance of your printer. Make these measurements in the three directions of the piece (X, Y, Z).

Difference between tolerance and slack

Now that we know the tolerances of our printer, we can design taking into account the slack . The slack is the minimum separation between pieces that we must leave in the design. As a general rule, we can assume that it will be double the value of the tolerance obtained.

If you still want to know which slack values ​​are the ones that work best for your design, you can try the following model for 3D printing .

slack test for 3D printing

Slack test for 3D printing

How to improve the tolerances of your printed pieces

Improving tolerances means reducing them. It is always possible to reduce these values, especially if they are very high. For this there are a series of steps that you should follow:

  • Check the moving parts of your printer: If these parts are damaged, they will affect the dimensional quality of your prints. Check the motors, belts and bearings and replace them if necessary.
  • Use quality filament: A filament of low dimensional quality will lead to an inconsistent extrusion, which will affect the measurements of your piece.
  • Make sure you calibrate your printer: A poorly calibrated printer is the best friend of bad tolerances.

And that's all for today.

Greetings and see you printing

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