GMU:RapMan/HowTo

In this HowTo you will learn how to print a 3d object on the RapMan.

Creating 3d objects

For help on what software to use please look at the links.

There are a few guidelines you should keep in mind when desinging objects for the 3d printer.

• You can't print overhangs steeper than 45 degrees without support material. Generally this is nothing to worry about though support material sometimes can be hard to be removed.
• Thin solid walls must have a specific thickness, currently we are limited to 1mm, 2mm, 3mm... Any x.5mm will result in hollow walls. This is due to our extruder nozzle being 0.5mm in diameter. Above a certain thickness (I think 5mm) any value is possible, so 10.1mm walls will print just fine.
• When parts must fit into each other design with a tolerancy of ~0.5mm. Any holes or inner sides must be .5mm larger: a 3.5mm hole will be printed as 3mm hole.

Before you print

The RapMan v3.1

Before touching the printer make sure you have at least once read the manual and then contact Matthias. A printed version of the manual is somewhere around the printer. Should it not be, go and download it and read it thoroughly.

The are a few things you have to do before actually printing your object. You have to chose the right filament to print with, export your 3d-model to the right format, check the printer for parts that might have become loose during a previous print and check that the filament spindle unrolls easily.

Choose your filament

File:RapMan HowTo-filaments.jpg

Different filaments (ABS and PLA)

Chosing the right filament to print with is usually the first step when printing an object. The different plastics have different properties that might influence your print and each plastic has its own export settings. There is a good overview of commonly used materials over at the BfB Wiki. Our default material is PLA so i recommend to stick with it.

Preparing your data

Stl file in Meshlab

Preparing your data for printing is divided into two steps.

1. Export your 3d-model to stl format
2. Convert the stl data to G-code using Axon or Skeinforge

It's wise to use software like Netfabb or Meshlab to check your exported stl file for errors and do minor tweaks like rotating and scaling.

Using Skeinforge

Skeinforge is a collection of Python scripts that slice the model and create toolhead paths. Skeinforge runs on Linux, Mac and Windows machines but is somewhat hard to use. If you are new to our 3d printer I recommend to use BfB Axon which is described below.

Using BfB Axon

BfB Axon is a fancy frontend to Skeinforge supplied by Bits from Bytes. It comes with great profiles for PLA, ABS and ABS/PLA mix but only runs on windows. Since we have a dedicated windows machine in the printer room you should use Axon unless you know how to use Skeinforge.

Checking the printer and filament spindle

Some locations where screws might loosen

During the printing process screws of moving parts might become loose. Since the whole printer is jerking around sometimes this could be anywhere. Some places you should always check are the screws of the x- and y-stepper motor pulleys and the screws of the extruder gears. Also check if the belts are tight enough. Loose screws of motors and gears will make your print look ugly.

Also don't forget to check that the filament spindle unrolls easily. If this isn't the case the filament might get entangled and you have to manually disentangle it which of course will most likely spoil your print if you notice too late.

Printing

The RapMan printing

Printing is fairly easy. Copy the G-code file to the sd card, put it into the RapMan controller and power it on. Then select your file and run it.

After you print

The printed object

After your object is printed there are some steps you might want to do:

• Remove the raft
• Remove any excess filament
• Redrill holes

Removing the raft shouldn't be too hard, use a sharp knife for this task. The extruder leaves some excess filament when it does hard turns or stops for a moment. The excess material creates visible seams on your object. The best way to remove them is to use a knife and cut off anything that's big and comes off easily. Anything else must be sanded. Use sandpaper or the band sander from the workshop. Holes in your object will not have the same exact diameter as in your 3d model. Use the stand drill to redrill any holes that must have a specific diameter. When using a drill on plastic never use high rpm or else the plastic will melt and destroy you drill bit.