FDM 3D Printing DIY Training

If you want to train yourself on an FDM 3D Printer, you will need to have a thorough understanding of what is covered in this user guide. A staff member can give you a credential allowing you to use an FDM 3D printer independently if you can demonstrate an understanding of the 3D printing process. This includes:  

• A walkthrough of how you would set up a printer on Cura, including a brief explanation of the core settings (I.e. walls, infill, materials) 
• What are some safety precautions you should take when operating a 3D printer? 
• What is the anatomy of a 3D printer? 

This document will walk you through the basics of FDM printing. Text in black explains certain concepts.

What is an FDM 3D Printer? 

FDM stands for “fused deposition modeling”. An FDM printer melts plastic and extrudes it in a pattern—basically, depositing layers of fused plastic to make a 3D model. The pattern is determined by a digital 3D model, which a printing software will “slice” into layers. 

Printer Anatomy 

The printers we use are Ultimaker S3/S5s, which are virtually identical except the S5 has a larger build volume (230 x 192 x 200 mm vs 330 x 240 x 330 mm).

Downloading Software + STLs 

Cura, the free slicing software used for Ultimaker, can be downloaded here. Workstations in the 3D print room will have this software installed. In this training, we’ll be learning how to 3D print with Benchy. Benchy is a popular 3D print testing file, since it’s small and has enough detail and overhanging parts to demonstrate what works best for your print settings.  

Load your part into Cura 

4. Your part will appear in the Cura workspace window. If it fits in the printer workspace, it will appear yellow. Otherwise, it will appear striped, and a striped piece is too big to be printed. 
5. A yellow piece with red patches on the underside is okay: those patches indicate where supports will be placed. Supports are tiny scaffolding designed to support a piece, so it doesn’t collapse during printing but can still break off easily from the finished piece. 
6. Click the yellow model to bring up the placement menu on the left side. Use the top four buttons to adjust your piece: 
   • Move will let you reposition your piece.  
   • Scale will change the size of your piece. If you are making a functional rather than a decorative piece, be careful: this will also resize things like bolt holes. 
   • Rotate will change your piece’s angle, which is the most important placement setting to get right. Rotate your piece, so it sits securely, and won’t need too many or too tall supports. 
   • Mirror will reflect your piece around some axis, so you can create two images that reverse each other. 
7. The other two options, “Per Model Settings” and “Support Blocker,” should be left alone.

Select print settings 

1. Material: Select the material you’re using: either PLA or ABS. PLA is less finicky of a material to print with and recommended if you’re new to printing or printing things for fun. ABS is a more “industrial” material, so it’s recommended if you’re printing parts for a larger project.  
2. Resolution is how thick the slices are. Smaller layers will mean the print is of higher quality, but it will also take longer since there will be more layers. A good layer height is 0.25 mm – if you want to print thinner than that, ask an Explorer if that’s okay. 
3. Shell thickness is the outside of the piece. Printed parts are semi-hollow, but the shell is solid up to a small depth. A suitable wall thickness is 0.6 mm, strong and thick enough for scratches. If you are printing something that needs to support a lot of weight, you can turn the wall thickness up to 1 mm. 
4. Infill is the inside of a 3D-printed part. Typically, it’s filled with a honeycomb pattern, but this can be changed depending on application, as some patterns provide strength in different directions. You can change infill density as well, and 20% infill is a good number. Even as low as 10%, a piece will still be strong. 30% is very high and should only be used on pieces that need to support a lot of force. Higher infills will extend the print time and use more filament, so don’t make it higher than you have to. 
5. Supports are printed scaffolding that supports any overhanging or curved parts of your piece to prevent it from collapsing. Supports are made to break away easily, so you can remove them after you print. Check the box to make Cura automatically generate supports if you want them. 
   • Best practices for supports: While supports do break off easily, you shouldn’t have supports on important features of your project (parts requiring highly precise dimensions, the most aesthetically critical parts of your print, etc). This is because the supports will slightly warp whatever they’re attached to and could also chip your part when you remove them. While of course you can sand away imperfections, that might mess up any important features. 
6. Build Plate Adhesion determines what prints where your piece sits on the build plate. There are four options: None, Skirt, Brim, and Raft. We recommend a brim for all PLA parts and most ABS parts or a raft for ABS parts that seem more likely to warp. These are in the advanced settings.
   • None means the printer will start with your piece without making a base, which is risky, as prints are more reliable with a base. 
   • A Skirt is a thin line of filament that outlines your piece but doesn’t touch it. This is almost the same as None, but it gives the extruder a chance to warm up first, making it slightly less likely to jam. 
   • A Brim is a thin sheet printed beneath your part. A brim helps your piece adhere to the build plate, holds the bottom flat during the early stages of the print when the piece is thin, and gives the piece protection against scratches when you remove the piece from the printer. Brims are usually the best option. 
   • A Raft is a much thicker version of a brim, and it serves the same benefits but is much better at preventing warping. It has the downside of increasing the print time and using extra filament, so it should only be used when warping is a concern. 

Operating the Printers

Printer Check-up

Troubleshooting: Sometimes, 3D printer print beds don’t heat up well or have built up residues from old prints, which means that prints won’t adhere well. If this happens to you even though you’re using a brim, you can use a thin layer of Elmers glue stick on the print bed. Please note that you are responsible for cleaning off any leftover glue with a damp paper towel after you collect your print. 

Load part into the Ultimaker Printer itself

While your part is printing 

1. Part of the beauty of 3D printing is that after setup, the machines are completely automated. You don’t need to stick around for the whole process, but you need to watch the first few minutes. 
2. The printer will heat the bed and the nozzle, which will take a minute or so. Then it will move to the front left corner and extrude a small blob of filament. This is to ensure the machine extrudes properly – if you don’t see a blob, pause the print and ask an Explorer to help you fix the filament. 
3. The vast majority of 3D printing failures happen during the first few layers. Watch the printer make the brim or raft, and let it print enough to be sure it’s working. If something goes wrong, stop the print and ask an Explorer to help you fix it. 

Basic printer maintenance

Loading and Unloading Filament

1. Go into the settings. You will see a screen that will display the filament type, nozzle core names, and the name of the build plate.
2. To unload filament: Click the name of the filament that you want to change out. Hit unload and follow the instructions on the machine. Make sure your tension lever is OPEN before unloading. The machine will automatically unload the filament on the Bowden tube, and when the filament is entirely out of the machine, you can remove the spools from the machine.
3. To load filament: Take your spool of filament and, using a pair of flush cutters, cut the filament at an angle. This will make it easier to install. Make sure your tension lever is OPEN, and then insert the filament into the loading hole until you see it go through the Bowden tube. Close the tension lever and then follow the instructions on the screen until filament is loaded.

Removing/installing the print bed

1. When the bed is COOL, turn open the metal clamps at the front of the bed.
2. Pull the bed out gently.
3. To install the bed, push it back onto the machine. Make sure it’s flat and hooked into the back metal clamps before clamping it down in the front.

Retrieving your part

1. Make sure you know how long your print will take and when it will be done. Try to come back and get it soon after it is ready. This saves the next person the trouble of removing your part from the bed and avoids the risk that someone will mishandle it. 
   • Use common sense here. If a part is going to be done at 3 am, you don’t have to get it then – sometime the next day is fine. 

Our 3D Printing Policies

• Pay for your print before or after your part! It doesn’t matter when, as long as you do. Grab a staff member who can help you pay; we pay per gram of material.
• The Laundromat Model: We use a “”laundromat model” for our printers. If a machine is open, you can put your job onto it. If all the machines are empty, you may remove the person’s job from the printer and load your own job onto it, just like how laundry machines work in communal spaces. That being said– do not get upset when someone else touches your parts if you take too long to pick them up.
• Reprint policy: If your print fails and it’s a printer issue, you may reprint for free. If your print fails and it’s because you sliced it poorly, you may reprint for free provided that you complete a reprint form and save your failed part! We use these to teach other students about common printing failures.
• Do not change out print filaments or print cores.
• Do not bring your own filament— we have a dedicated printer for people who bring their own filaments in.
• Always write your name and email. If you don’t and your print fails, we will have no way to contact you!
• Don’t be “That Person”: Don’t be the person who uses up every machine with 20 hour long prints and takes up all the communal space and material. If you think you are using too many printers, you probably are.