Materia 101: A Tutorial About Avoiding Warping

1. Level the bed one more time.

• Start to print the object.

• Stop the print when the printer reaches the horizontal roof.

• Look at the surface of the bottom of the piece. Especially look at the corners of the object. What we are looking for is strains of plastic that touch each other without flattening the first layer to much. If it is flattened to much the details touching the print surface will be lost and in this case the brick won’t be be compatible with your LEGO pieces. This way you can adjust the bolts in each corner of the print surface. If one of the corners is too flat, turn the bolt in the closest corner clockwise to increase the distance of the surface from the nozzle in that corner. A quarter of a turn might be enough. Don’t overdo it.

OR

• Go to the prepare menu on the printer.

• Scroll down until you get to the “Prepare" plate option and click on it.

• The hot end will heat up and the printer will wait for your instructions to start the calibration.

• The printer will start drawing a big square and will then ask you to adjust the screws.

• After this you’ve done so you can press the rotary encoder again and it will draw another smaller square.

• Adjust the screws again and press the rotary encoder.

• Now the printer will print a circle. This is to check if the y and x axis is squared.

2. Adding “Ears” to your object

On other prints we could use a brim to avoid warping. You find the "Skirt and Brim" option under the "Print Settings" tab, after you have chosen "expert" in the mode drop-down menu instead of "simple".

But since we have small details on the bottom of our object, adding a brim would make our object unusable. Adding small round ears on the corners of the object is a good way of making sure that the object does not lose its grip on the print surface and warp. The size of the ears could be about 5 to 10 mm in diameter. The thickness of the ears could be about 4 layers.

Here is a video of the step.

• In FreeCAD open the battery holder Lego adapter. Be sure to be in the “Part design” workbench.

• Rotate the object so that you see the bottom of the object. You do this by holding down the scroll wheel on your mouse.

• Click on the face of the outer edge of the bottom.

• Go to the tasks tab in the combo view and click on create sketch (under face tools).

• Click on the external geometry tool in sketcher geometries toolbar and click on the top outer line of the edge.

• Draw a circle with the circle tool.

• Draw a line from the reference point downward to the edge of the circle.

• Draw another line from the reference point to the right to the edge of the circle.

• Add a horizontal restraint to the horizontal line and a vertical restraint to the vertical line.

• Use the “Trim” tool to remove the arc that is on the inside of the bottom of the box.

• Exit the sketch.

• Go to the combo view panel and click on the tasks tab.

• Click on the “Pad” button.

• Set the length to 0.6 mm. The length here equals the height of the ears. 0.6 mm equals a layer height of 4 layers, when printing at a layer height of 0.15 mm.

• Click OK.

3. Add holes on the sides of the object to disperse the tension

The shape of the object place a role in how the object changes shape when being printed. Long horizontal shapes add up tension after a few layers and starts to pull on the less massive parts of the object, such as the corners.

Here is a video of the step.

4. Using painters tape instead of hairspray

I’ve had different results using hairspray for 3D printing. There are good brands and there are bad ones. The key ingredient seems to be vinyl neodecanoate copolymer in good hairsprays (at least for the purpose of 3D printing).

I switched over to using blue painters tape instead of hairspray. The brand I’m using is Scotchblue painters tape. The 2090 kind seems like the best one. It keeps the parts on the print surface as long as you don’t get the tape very fatty and dirty and you can clean it with acetone or isopropylate to get rid of the fat.

When applying the masking tape to the print surface do it in a non-overlapping manner. Do not leave gaps between the strips of tape.

Other solutions worth looking into is using the Blue UHU glue stick straight on the glass surface.

5. Using a higher temperature on the first layer

The object's overall size decides the temperature we can print it at, this however is within the temperature span of the material we are using.

For the battery pack holder we are going to use these temperatures: Extruder: First layer: 215 C Other layers: 210 C

In general you can think about size, volume and temperature.

• Bigger object i.e. larger areas and higher temperatures. Use higher temperatures (enables you to get stronger objects, print at higher speeds and you get a better attachment to the print surface. A high temperature on the Materia 101 for PLA might be 230 C for the first layer and 225 C for the rest.

• Smaller objects i.e. small area and lower temperatures. For these objects use lower temperatures and a lower speeds. The plastic sets at a certain rate and has a elasticity until it’s set. Therefor if we lay it out too fast the plastic will retract and make longer horizontal shapes become slightly arched. Another noteworthy thing about printing small object is that the plastic retains some heat hence we need to print slower to let that heat dissipate and not add to it the next time the nozzle passes that area.