Transcript
3D printing 101 (This document last updated 08/03/2017)
This document accompanies a live training class at Ace Monster Toys. You must attend the class before using the 3D printers. There are two sections to this document: • •
The general section has information common to all 3D printers The printer-specific sections give necessary detail for each printer
General There are 3 steps to making something on the 3D printer: • • •
Get an STL file Slice it Print it
Get an STL file A file in STL (Stereo Lithography) format is the input to the 3D printing process. Export from your 3D modeling program to STL, or download a 3D printable STL file from the internet. 3D modeling is beyond the scope of this class. Check the CAD-CAM group on slack; come to a 3D printing hangout; or look into our frequent Fusion 360 workshops. We have some related articles on our blog as well.
Thingiverse.com is the most popular site for sharing 3D printable designs, and is a great way to get started. Look for proven designs that have actually been printed at least once, and download the STL file. Start small! Big models take much longer to print! Slice A specialized software package reads the STL file and creates a tool-path that drives the 3D printer. We call this slicing, since the solid model will be sliced into layers as a first step. There are a number of slicing programs available, and they all have lots of settings you can adjust. We make specific recommendations in the per-printer sections below. Stick to the recommended defaults for your selected material and printer unless you have good reason to deviate. There are a few slicing settings that you probably will want to adjust: Material We recommend PLA unless you have a very good reason to use something
else. This general purpose plastic is the default material for the slicing software, and is by far the easiest to work with. We have a bit of PET as well. It requires higher temperature settings, detailed in the printer-specific sections below. We do not recommend ABS due to the toxic smell and warping issues. We do not have experience with flexible materials (Ninjaflex™), but we'll update this document when we do. Quality The layer height is the principal setting that affects print quality. Smaller layers give higher quality but take longer to print. Most slicers have quality 'presets' that set layer height and all other quality-related settings to sensible values. Support If you have overhanging features in your model, you may instruct the slicer to add support material to be broken away after printing. This sometimes works great; sometimes not. Consider redesigning your model to eliminate the overhangs (perhaps by assembling two pieces instead). Raft or Brim If you have a large part that is supported by just a few thin points, it may come loose from the bed before the job is complete. If so, the 'raft' or 'brim' features will add a breakaway layer to help bed adhesion. If you have a reasonably large flat surface on the bottom of your model, leave raft and brim turned off. Infill The printer prints a solid skin around a semi-solid latticework interior. The fill percentage sets the density of this latticework, with 100% being solid plastic. Use the following settings as a guide: 15% - light duty 25% - medium 40% - heavy duty 40% is much denser and stronger than you might think; there's seldom any reason to go higher. You'll just be wasting time and plastic. Print Printer setup details are in the specific sections below. All our printers now use an SD card for standalone printing. Please use this method as it is more reliable than printing via USB and frees up the 3d print computer. Put the slicer output file on the SD card for the printer you intend to use. Don't forget to eject the SD card before removing it from the reader on the 3D print computer. Please leave the SD cards in their respective printers and don't borrow them for other purposes. The Replicator2 in particular uses a hard-to-replace old-style SD card. When loading a new spool of filament, it’s a good idea to unroll 6-8 feet of it first, to make sure there are no ‘overruns’ that might tighten up and form snags during the print. Then carefully roll it back up before loading the spool. Check, every so often, to be sure the filament is feeding freely while the job is underway.
Materials We have material for member use in the black chest of drawers. Be sure to check the label to see what the material type is (PLA or PET). You may also bring your own material. Check with the steward for recommended suppliers. If you're planning a large project we'd appreciate you supplying your own material. General Troubleshooting The Simplify3D website has great photos of typical 3D printing problems. http://www.simplify3d.com/support/print-quality-troubleshooting/ Their recommendations will have to be translated to the slicer you're using.
Prusa i3 MK2 Our newest printer, the Prusa i3 Mk2, is the easiest printer to use, and probably the most reliable. It does have some idiosyncrasies that must be understood to get good results and avoid damaging the machine. Heated bed with PEI print surface This is the only printer in our stable with a heated bed. It is used even for PLA to improve adhesion and minimize warping as parts cool. Keep the bed set at the recommended 55C for PLA. The bed has a special PEI surface that does not require blue tape. Before each print, use the isopropyl alcohol or denatured alcohol to clean finger grease off the bed. You can do so even if the bed is warm. (For PLA it doesn't get all that hot). Please DO NOT put blue tape on the Prusa bed! You should not need to use a glue-stick, or any other “magic sauce” to get good bed adhesion with PLA. If your print job is not sticking, something else is wrong! (see Live-Z below). Automatic bed leveling The I3 has no provision for manually adjusting the bed. Instead, the firmware probes the bed with an inductive sensor at the beginning of the job and adjusts the nozzle position to match. It works like a dream, but you must Use a slicer configured for this printer! ...so that the required commands are properly embedded in the g-code. If you fail to do this, the probing sequence will not happen, resulting in a bad print (best
case), or a print-head crash that will at least damage the PEI surface and might even damage the nozzle or printer mechanism.
Slicing Prusa has created a fork of the open-source Slic3r program with some bug fixes and advanced features. Most importantly, they have created nicely-tuned profiles for the i3 Mk2. Select the quality profile; filament type, and printer on the Plater tab. If you change a setting please do not save it back to the original profile. If you save a custom profile, be aware that it may be purged from the 3D print computer from time-totime. There are three printer profiles installed:
Original Prusa i3 MK2 with Zhop Original Prusa i3 MK2 ColorPrint Original Prusa i3 MK2 .025 Nozzle with Zhop
This is the one to use in general Use only when using Colorprint Don't use; our nozzle is 0.4mm
See the Slic3r website for general instruction and the Prusa website for details of this fork: http://manual.slic3r.org/ http://www.prusaprinters.org/introducing-slic3r-prusa-edition/
Printing Check that the gantry is level The gantry driven by two steppers that remain in sync when the machine is running. When the machine is powered down, these may be turned individually and fall out of alignment. To correct this, choose Settings/Move Axis/Move Z and turn the knob to raise the gantry. Raise it all the way to the top and then just a bit more until both sides of the gantry contact the top supports. The motors will “grind” a bit at the top. This sounds awful, but is normal and no cause for concern (The motors are low power and are electrically “cogging” -- they're not grinding any physical gears or belts). Strange as it may seem, this is the official recommended procedure; see the printing handbook, section 6.3.6. Load/unload filament First, select Settings/Move Axis/Move Z and turn the knob until the nozzle is a few inches above the bed. Find the Preheat item for the filament you're using and click it. Wait for the nozzle to come up to temperature.
Click the Load/Unload filament item. It will tell you to preheat if you forgot. Then it will prompt you through the rest. Start the job Select print from SD and choose your g-code file The printer will warm up first; then probe the bed in nine points and start printing your job. While the print is happening The panel will show percent-finished and elapsed time. Use this to estimate overall time. You may adjust the speed by turning the knob while the main status screen is displayed. By default it's 100% of the speed selected in the slicer. For simple parts you may be able to push the speed a bit faster; for parts with a lot of short head movements, you may want to slow it down to minimize shaking. There are a few other things you can tweak while the job is running. This may enable you to rescue a job without having to reprint the entire thing. If the first layer is not sticking well, try the Live Adjust Z item to tweak the first layer thickness. The manual has excellent photographs of what to look for in section 6.3.9. The Tune menu allows you to adjust speed, temperature, extrusion flow, etc. on the fly. You can change filament on the fly too; Nice if you want to use up that last bit of filament on the spool. Removing your model The bed is not removable. Carefully use a polished spatula to loosen the model from the bed. Try not to dig into the PEI surface... we want it to last as long as possible. Manual The printer manual is excellent. We have a hard-copy hanging on the wall. You can also find it online at: http://www.prusa3d.com/drivers/. Look for "Original Prusa i3 MK2" Multi color printing! Well... sort of. The Prusa website has a utility that will insert a pause to change color at a particular layer. You must prepare your job properly first; see the manual. It's fun! Troubleshooting If the first layer doesn't stick properly stop the job
clean the bed print the 'V2Calibration.gcode' file and tune the first layer with the "Live Adjust Z" feature as described in the manual section 6.3.9. Let's try to leave this V2Calibration.gcode file on the Prusa's SD card. If the machine is badly out of alignment, contact the steward. You may also perform the calibration steps 6.3.5 and 6.3.6 in the manual. Please let the steward know if you found this necessary.
Makerbot Replicator 2 Slicing The Replicator 2 uses its own file format with the extension .x3d. This is produced automatically by the Makerbot Desktop slicer, which is the one we recommend. Makerbot Desktop has three quality profiles, Low, Standard, and High. Each profile is a collection of individually adjustable settings. You may save additional profiles if you like, but be aware that we may purge them from time-to-time, so make a backup record of any settings you want to preserve. If a setting has been altered from its default, a green asterisk appears beside the related field. Go through all the tabs and click the green asterisks to return to defaults, then adjust any settings you want to change per the recommendations in the general section above. Makerbot Desktop defaults to a fairly high nozzle temperature for PLA: about 230C, whereas the Type A and Prusa are happier at about 215C. The higher temperature does seem to work well on this printer; lower temperatures seem to cause more frequent jamming issues. Click Preview to examine the slice results if desired. Then Export Print File, or just Export on the preview window. Insert the Replicator 2's SD card and save.
Printing Tape the bed The bed is a simple piece of Acrylic sheet. Please do not print directly on this surface. Cover the surface with blue painter's tape. If you level the bed carefully, the same tape may be re-used several times. Be sure to cover the area near the front of the build plate, as the jobs always begin with a 'nozzle priming' line placed there. You may clean the tape with a quick wipe of Isopropyl Alcohol. If the tape tears when removing your print, pick the torn bits off and replace with a fresh
piece of tape. With care you can butt the tape up against the last strip and get a fairly clean bottom surface. Load / Unload filament The Replicator 2 has convenient menu items to load and unload filament. It will automatically preheat the nozzle for you. Level the bed The bed must be manually leveled on the Replicator 2. Click the menu item and follow the instructions except for the first step, which suggests that you initially tighten all the screws. (The bed is probably close enough that you can omit this step). Use a piece of ordinary bond paper as a feeler gauge. The bed is properly adjusted when the paper may be moved, with a slight amount of 'drag'. Just how tight is a matter of feel and experience. In the 101 class, the steward will demonstrate for you. Improper bed leveling is the cause of almost all failed prints. It should be the first thing you check, even if you just printed a job perfectly. Start the job Select print from SD, and choose your .x3g file. Monitor the first few layers carefully. If the plastic doesn't stick, clean and re-level the bed; it's probably too loose. If it doesn't extrude any plastic at all the bed may be too tight. Jamming issue related to wonky fan In mid-to-late 2016 we had frustrating issues with the nozzle jamming, which turned out to be intermittent failure of the extruder fan (the front one). We have since bypassed the original circuitry and seem to have addressed the issue. This front fan should be running at all times when the printer is turned on. Please keep an eye on it and be sure it does. The side fan cools the work-piece and will turn on and off depending on slicer settings; typically off for the first layer and on for the rest. Clearing jams We have detailed instructions on the Wiki for clearing a jammed extruder; it's an annoying job but is not difficult. If it jams, please don't just walk away! http://wiki.acemonstertoys.org/How_to_un-jam_the_Replicator_2_Extruder
Type A Machines Series 1 We heavily modified the Series 1 in 2016 to make it easier to use. Nonetheless, it’s still has a rather touchy bed leveling procedure. Despite its age and somewhat funky appearance,
the quality is the same, and the capacity is the largest in our fleet. Slicing We have added a profile for our Type-A to the Prusa-Edition Slic3r for use with the Type-A. Use Slic3r as described for the Prusa, except: for printer profile select “AMT Type A” for filament select “Prusa PLA 1.75mm NO HEAT BED” Printing The bed must be taped with blue tape just like the Replicator 2. This is a little more difficult to do since the bed is not as easily removed. Changing filament Use the control panel to preheat the nozzle to about 210 degrees (for PLA), and remove the filament by hand. Depress the lever on the extruder and simply pull the filament out. Load new filament the same way. To ensure that it’s flowing well, use the control panel to extrude a bit: Prepare/Move axis/Move 10mm/Extruder. . Removing the bed (don’t unless you must) The bed is mounted to the gantry by four screws:
The bed adjusting screws are secured to the bed through keyhole-like slotted holes, and are slightly spring-loaded. This enables you to remove the bed if necessary to remove a stubborn work-piece. It’s a little tricky to do, so don’t remove the bed unless you have to. Slide the screw heads to the wide end of their slots, and lift the bed off (you don’t have to remove the nuts). Do not tighten the topmost small lock-nuts just below the washers, or you will defeat the removable-bed feature entirely. Leveling the bed
There is a custom menu entry for leveling the bed. It will cycle through four points; one near each of the leveling knobs. Due to a bug in the firmware, you must select home all before starting the bed leveling procedure. We’ll try to fix this bug soon. How to adjust the knobs:
Use a piece of paper under the nozzle to feel the gap, just as in the Replicator 2. It’s a good idea to go through them all a second time as a double-check, as one screw can affect another.
