3D Printing: Make Something Real

What you'll learn

• How to find a model, check it will print, and give its designer credit
• How to design a 3D model in Tinkercad from shapes, holes and exact measurements
• How a printer turns your model into an object layer by layer, and why resin and filament printers do it differently
• How to run a printer properly: slice the file, set up the machine, finish the print, and leave it ready for the next person

What you need

• A lab computer with a web browser, and Tinkercad, joined with the class code and a nickname
• One of the lab's two printers, your pick: the Formlabs Form 3 (resin) or the MakerBot Replicator+ (filament)
• For the MakerBot: the class flash drive
• A ruler or calipers
• Nitrile or neoprene gloves and safety glasses at the Formlabs wash station

Safety rules: resin and IPA

These are non-negotiable. Breaking one on purpose costs you printer access and earns a 0 for the day.

• Pass the printer safety check first. Nobody touches a printer, the resin, the wash or the cure before Mr. Krigger has checked them out.
• Gloves for anything wet: liquid resin, IPA, and any print not yet washed and cured. Nitrile or neoprene, never latex.
• Resin on your skin: soap and water, right away. Never IPA or hand sanitizer. Then tell Mr. Krigger. Touching resin again and again can make your skin react to it for life.
• Safety glasses for resin, IPA, and clipping supports. Supports snap and fly.
• IPA is flammable. Bottles and the Form Wash lid stay closed. Nothing hot near it.
• Resin waste never goes in the sink or the trash. Gloves, towels and failed parts go in the marked resin waste container.

Safety rules: every printer

• No food or drink at the print station.
• Hands out of any printer that is moving. The MakerBot nozzle runs at about 200°C, and its build plate stays hot after the print ends.
• Unattended prints: a Formlabs plate may run overnight under Mr. Krigger's rule. The MakerBot never runs without an adult in the room.
• Report spills, damage, a burn smell or an injury right away. You will never be in trouble for reporting something. You will be for hiding it.

The plan: two prints

How the printer queue works

• Every part fits in a 40 x 40 x 25 mm box. About the size of a matchbox standing up.
• Formlabs: one plate holds a whole class. It builds every part's layer at the same moment, so twenty short parts take about as long as one. Time depends on the tallest part. Plates run overnight.
• MakerBot: one part at a time, under 60 minutes, only while an adult is in the room.
• Failed prints go first next time.

Name every file like this, and write the same name on the Print Queue sheet:

HS-JK-print1.stl

Pick your printer

Your STL works on both printers. Only the slicing and the finishing change, so each printer has its own tab at the top of this page. On Day 3, open your printer's tab and follow it.

Day 1

Hands on, safety, and Print 1

Goal: by the end of today you have built a nameplate in Tinkercad, passed the printer safety check, and found Print 1.

Step 1: Build a nameplate

1. Go to tinkercad.com and click Log In. Choose Students, join your Class, type the class code, then your nickname: first name or initials, never your full name.
2. Click Create, then 3D Design.
3. Drag a Box onto the blue workplane. Click it, click the white squares on its sides, and type: 40 mm long, 15 mm wide, 3 mm tall.
4. Drag Text onto the box. Type your name or a word. Make it 2 mm tall and sink it a little into the box.
5. Drag a box around both to select them, then click Group.

Step 2: Two printers, two ways to build

Both printers build one thin layer at a time. They do it very differently.

Step 3: The printer safety check

Before you touch a printer, Mr. Krigger checks you out at the machine, a few of you at a time. While you wait your turn, start Step 4.

• You show where the gloves, the glasses and the resin waste container are.
• You say what you do if resin gets on your skin.
• You show the Form Wash lid closed, and say why IPA stays closed.
• You show where your hands stay while the MakerBot is moving.

Miss something and you take it again. Pass it once and the printers are yours for your own projects for the rest of the year. The full rules are in the Lab Safety lesson.

Step 4: Find Print 1

Print 1 is a model someone else designed. Today you are learning the machine.

Your model must: fit in 40 x 40 x 25 mm (you can shrink it), be school appropriate with no weapons or weapon parts, and download as an STL without making an account.

Step 5: Check it fits, then save it

1. In Tinkercad, click Import and choose the STL you downloaded.
2. Read its size. Too big? Hold Shift and drag a corner to shrink it evenly.
3. Make sure it sits flat on the workplane, then click Export, then .STL.
4. Rename it like HS-JK-print1.stl.
5. Formlabs: save it in the Plate folder on the PreForm computer. MakerBot: save it to the class flash drive. Either way, write it on the Print Queue sheet.

Before you leave today

A progress check, not the hand-in. The full list is in the Turn in tab.

• Nameplate built in Tinkercad
• Printer safety check passed
• Print 1 found, shrunk to fit, exported, saved, and on the sheet
• Page link and designer's name written down

Day 2

Design Print 2

Goal: by the end of today your own design is finished, checked against the design rules, and saved for printing.

Step 1: Choose your Print 2

Print 2 is your own Tinkercad design. Pick how far you take it.

Step 2: Measure, then sketch with numbers

A design that is 2 mm off does not fit. Measure the real thing, not your memory of it.

1. Nameplate: decide how big it is and where it goes. Fixing a problem: measure everything your part touches, like how thick the cable is or how wide the desk edge is.
2. Sketch your part on paper and write every measurement on the sketch.
3. Check it fits the 40 x 40 x 25 mm box.

Step 3: Build it in Tinkercad

Build a piece at a time, and check each piece against your sketch.

Step 4: Design rules, then save it

Then Export as HS-JK-print2.stl and save it the same way as Print 1: the Plate folder for Formlabs, the flash drive for MakerBot.

Before you leave today

A progress check, not the hand-in. The full list is in the Turn in tab.

• Print 2 chosen: keep it simple, level up, or fix a problem
• A sketch with measurements
• Print 2 designed, passing every design rule
• Print 2 exported, saved, and on the sheet

Day 3 · Formlabs

Slice, print, finish

Goal: your prints are sliced and on a plate, Print 1 is finished and in your hand, and the printer is ready for the next person.

Step 1: Slice in PreForm

1. PreForm is on one lab computer, already signed in. Do not sign in with your own account.
2. Click File, then Open, and choose your STL.
3. Check the printer says Form 3 and the material matches the cartridge in the printer.
4. Click Orient, then Auto-Orient. Click Supports, then Auto-Generate.
5. Look at the Printability check. Green is good. Red means it will not print: run Auto-Orient again, or tilt the part yourself.
6. Take a screenshot of your part with its supports. It goes on your Print Card.
7. Mr. Krigger puts the whole class on one plate and starts it.

Step 2: Before every print

The printer has to be set up right, or the print fails and the whole plate is lost. Check these with Mr. Krigger before a plate starts.

• Cartridge: shaken well, the right resin, pushed down level with the back of the printer, and the vent cap pressed open on top
• Tank: the same resin as the cartridge, clicked into its rails, no cured bits floating in it, the mixer at its home on the left
• Build platform: clean, with no old resin on it, pushed in and the handle locked down
• Cover closed

Step 3: Wash and dry

1. Remove the build platform and hold it over a paper towel, parts up.
2. Wash once in the Form Wash, lid closed, for the time on your resin's label:

3. Dry. Let the parts air dry completely when the basket lifts out.
4. Still sticky once dry? Wash again, straight away, in clean IPA. Sticky usually means the wash IPA is old.

Step 4: Remove, cure, clip

1. Remove the parts from the platform with the part removal tool. Push away from your other hand.
2. Cure in the Form Cure:

3. Clip the supports with flush cutters, glasses on, pointing away from people. Sand the bumps if you want.

Step 5: Leave it ready for the next person

1. Clean the build platform. Over a paper towel, scrape off any cured resin with the platform scraper, then wipe it with IPA on a paper towel.
2. Close the cartridge vent cap when the printer is done for the day.
3. Check the tank for cured bits. Found some? Tell Mr. Krigger. Only the plastic tank tool ever touches the tank. A metal tool scratches the film on the bottom and ruins the tank.
4. A tank out of the printer goes in its case with the lid on, out of the light.
5. Gloves, towels and support bits go in the resin waste container. Close the IPA and the Form Wash lid.

Mini lesson: why a resin part grows upside down

A resin printer has a tank with a clear bottom. A laser draws one layer of your part on the bottom of the tank, and the light turns that thin film of liquid into solid plastic. The platform lifts a hair, fresh resin flows underneath, and the laser draws the next layer. Thousands of times.

Your part hangs upside down from the platform the whole time. Anything that sticks out over nothing has no layer underneath to grow from. Supports hold it there. That is also why the tank film matters so much: every layer is drawn through it, so one scratch shows up in every print after.

Before you leave today

A progress check, not the hand-in. Next stop is the Day 4 tab.

• Both prints sliced in PreForm, with screenshots
• Print 1 washed, dried, cured, clipped, and photographed
• Build platform clean
• Waste in the container, IPA closed, lids down

Day 3 · MakerBot

Slice, print, finish

Goal: your prints are sliced and on the flash drive, Print 1 is off the plate and in your hand, and the printer is ready for the next person.

Step 1: Slice in MakerBot Print

1. Open MakerBot Print on the lab computer. It is signed in on Mr. Krigger's UltiMaker account. Do not sign in or make an account.
2. Check the printer is the Replicator+.
3. Click Add Models and choose your STL from the flash drive. Click Arrange to center it, flat side down.
4. Open Print Settings: Balanced, Raft on, Supports on if anything hangs out in the air.
5. Click Preview. It must be under 60 minutes. Longer? Make it smaller. Take a screenshot for your Print Card.
6. Click Export and save the .makerbot file to the flash drive, at the top level, not inside a folder.

Step 2: Print it

1. With Mr. Krigger there, plug the flash drive into the printer.
2. On the printer's screen, tap Print, then USB Storage, then your .makerbot file, then Print.
3. Watch the first few layers. The plastic should stick flat to the plate. If it curls up or drags around, tell Mr. Krigger to stop it.
4. An adult stays in the room until it finishes.

Step 3: Take it off the plate

1. Wait for the screen to say it is done, then for the build plate to cool.
2. Lift out the flexible build plate and bend it gently. The print pops loose.
3. Peel off the raft and supports. Safety glasses on if you use pliers.
4. Brush any plastic bits off the plate and put it back for the next person.

Step 4: Changing the filament

Out of plastic, or want a new color? Do this with Mr. Krigger.

Take the old filament out

1. On the screen tap Filament, then Unload Filament, and wait while it heats up.
2. When it tells you, pull the filament gently out of the extruder, then out of the tube, and take the spool off.

Put new filament in

1. Tap Filament, then Load Filament, and wait while it heats.
2. Put the spool on, feed the end through the tube, and push it into the extruder until it grabs it.
3. When plastic comes out of the nozzle, it is loaded. Tap Done.

Mini lesson: a very precise hot glue gun

The MakerBot pulls plastic string from a spool, melts it in the nozzle, and squeezes out a line thinner than spaghetti. It draws the outline of one layer, fills the inside with a pattern, then moves up a fraction of a millimeter and draws the next layer on top.

Each layer needs something under it. That is why a part that sticks out over nothing needs supports, and why the raft goes down first: it gives your part a flat, sticky floor to start from.

Before you leave today

A progress check, not the hand-in. Next stop is the Day 4 tab.

• Both prints sliced in MakerBot Print, under 60 minutes, with screenshots
• Print 1 off the plate, cleaned up, and photographed
• Build plate clean and back in
• Flash drive back where it lives

Day 4

Finish it and show it

Goal: both prints are finished, and your Print Card is filled in.

Step 1: Fill in your Print Card

One page about your prints, like the card next to an object in a museum.

Write it in a Google Doc or on paper, then make it a PDF or take a clear photo.

A Print Card, filled in

While you wait, and if it fails

Open build days

• Finish your Print Card. Most people underestimate this one.
• Try a bonus challenge, next.
• Help someone whose print failed find out why.

If your print failed

1. Look at what came out, or did not, and write down what you think went wrong.
2. Check the design rules and the slicer, fix it, and tell Mr. Krigger. Failed prints go first next time.
3. Failed twice for a reason that is not your design? Your STL, your slicer screenshot and a photo of the failure count as your print.

Bonus challenges

Optional, for anyone. None of these are part of what you turn in. Each one you finish and show Mr. Krigger earns bonus points.

AI Lab: the rules

AI is useful for design if you stay the designer.

• Use only an AI tool on your school account that Mr. Krigger has approved. Do not make a personal account. Many AI tools need you to be 18, or 13 with a parent's permission.
• Never type your name or anyone's personal information into it.
• You must be able to explain every line or step it gave you. If you cannot explain it, it is not yours.

AI Lab, Route A: reading the code

Here is what OpenSCAD code looks like. It makes a 40 mm key tag with a hole and raised letters.

// Key tag: 40 x 20 x 3 mm, a 5 mm hole, raised letters 1 mm tall
difference() {
  cube([40, 20, 3]);
  translate([6, 10, -1]) cylinder(h = 5, d = 5, $fn = 40);
}
translate([12, 6, 3]) linear_extrude(1) text("VI", size = 8);

1. Paste it in and press F5 to preview.
2. Change one number yourself and press F5 again. Predict what will happen before you look.
3. Press F6 to render, then File, Export, Export as STL.

AI Lab, Route A: can you explain it?

Quick test on the key tag code. Here are its first lines again:

difference() {
  cube([40, 20, 3]);
  translate([6, 10, -1]) cylinder(h = 5, d = 5, $fn = 40);
}

Before you leave today

A progress check, not the hand-in. The full list is in the Turn in tab.

• Print 1 and Print 2 finished and photographed
• Print Card filled in
• Exit ticket done in class
• Optional: a bonus challenge shown to Mr. Krigger

Base and Stretch

What you turn in

• Print 1 and Print 2, shown to Mr. Krigger in class
• Print 2's STL file
• Your Print Card, as a PDF or a clear photo, with photos of both prints

Handing it in

Two things to hand in, not one

Show it off

Put your print where it gets seen or used. Strong prints and their Print Cards may be shown at school events and on this site, using your nickname only and only with your permission.

If you passed the safety check, the printers are now yours for your own projects too. Bring Mr. Krigger an idea.

Vocabulary

When it goes wrong: spills and skin

When it goes wrong: models and prints