3D Printing Instructions MANTIS CHENG

Transcription

1 3D Printing Instructions MANTIS CHENG

2 CHAPTER 1 How to Print on Thing-O-Matic Our Makerbot Thing-O-Matic (TOM) 3D printer is now several years old. It is not running the latest firmware. It doesn t work with the latest version of MakerWare (2.4.1). So instead, we use the latest version of ReplicatorG (0040) with Sailfish (enhancement) to control it. There are a few parameters that must be set correctly in order to make a successful and "precise" 3D print. We only print ABS plastic on TOM. Its build platform must be heated in order for the ABS plastic to stick. There is a layer of Kapton tape (yellowish color) on the build platform. The Kapton tape must be smooth in order for the ABS plastic to stick well. If it is damaged, for some reason, it must be replaced with another piece of 10cm wide Kapton tape. The ABS plastic is fed from a spool of filament from the top. Pay attention to the spool while printing. The filament can get tangled inside the spool; as a result, your print job will fail. Check it occasionally and untangle the filament if necessary. Use your favorite 3D design (e.g., TinkerCAD, 123D Design, SolidWorks) software to create an STL file for printing. If your software can specify dimension precisely, then it will be a lot easier to prepare the G-code for printing. Otherwise, you need to scale and adjust the print size inside ReplicatorG, which doesn't support resizing and dimensioning very well. Start ReplicatorG. Choose the "Machine Type" for "Thing-O-Matic HBP Extruder Mk 6 (Sailfish)". Choose Connect. If it works, then it is ready. 1

3 After loading an STL file into ReplicatorG, check your object s dimensions, whether it will fit inside the build platform. The largest object that can be printed on TOM is 10cm by 10 cm by 10 cm. After you scale your object inside ReplicatorG, check whether the object is placed on the platform in the centre. You can do that with the "Move" command beside the main preview window. Just click "Centre" and then "Put on platform". If all goes well, you are ready to generate the G-code. The following controlling parameters must be set during the G-code generation step: Plastics: ABS (default for Thing-O-Matic) Layer height: 0.4mm Filament diameter: 3mm (grey), 2.9 (red) Nozzle diameter: 0.5mm Feed rate: 20 mm/s (if you want good quality, don't set it too fast!) Travel rate: 30 mm/s Build Platform temperature: 130C (default) Extruder temperature: 225C (grey, red), 235C (black) In-fill: 15% (don't set it higher than 20%) Shell: 2 (or 1, in addition to the first shell) After generating the G-code successfully, the G-code will be shown in a separate tab in ReplicatorG. Now, save both G-code or any change to your STL model. Then, click "build". Wait until the extruder and build platform have reached the correct temperature. You can see the current temperature in ReplicatorG. Just before the extruder starts printing, lower the "extruder" counter-weight on top of the printer gently. Without the counter-weight, the z-height may skip layers due to vibration. After your print job is completed, wait until the temperature of the build platform cools down to around 90C. Then, gently lift the object from the build platform using your fingers. Use a plastic spatular if needed. If you are careful, the Kapton tape should remain intact. If the Kapton tape breaks, then replace it with a new one. There is a heating element underneath the 2

4 Kapton tape. NEVER use a sharp metal tool to remove the printed object; it may break the heating element! It is costly to replace the heating element, which is a PCB with thick traces. Without the heated platform, we can't print ABS plastic. So, be very careful! Good luck! 3

5 SECTION 1 Generating G-code In our lab, there are 3 ways to generate G-code from your STL files, i.e., slicing. Some are easier; some are more flexible and thus can produce better results. Skeinforge (supported by Replicator-G), very slow and is written in Python; Slic3r, very fast and very flexible; Makerware (version 2.4 and later), easy to use and produce reasonably good results. ReplicatorG is a slicing program as well as a control panel for many opensource based 3D printers. Its built-in slicing engine is called Skeinforge, which is written in Python. It is relatively slow (100x slower) as compared to others. You can speed it up using the JIT compiler PyPy for Python (which is already installed on our laptop). You can also use ReplicatorG to control TOM, e.g., calibrating the initial Z height, preheating the extruder, etc. You can use it to send the generated G-code directly to the 3D printer via the USB cable, and monitor the printer s status while it is printing. We have used it for several years now. So, it is a proven solution for 3D printing. For using our TOM, you must use ReplicatorG to control it since there is no built-in display on the printer. (In the future, we will update its firmware so that it will work with MakerWare, which is much easier to use.) Slic3r is one of the best open-source slicing programs. It is very fast, flexible and can produce very good results. Please watch the online video on YouTube, Introduction to Slic3r presented by the original author. It discusses many interesting issues with 3D printing and how to optimize your results. Slic3r is only a slicing program; it cannot be used to control any 3D printer directly. You use it to slice an STL file into human readable ASCII G-code. To use the exported G-code with TOM, you need to import it into ReplicatorG. This is just an extra step. (To 4

6 use it with Replicator 2, then you need to convert the ASCII G-code into compressed G-code using MakerWare because Replicator 2 can only accept compressed.x3g G-code files. See below.) If you want good results, then it may be worth your while to try Slic3r. Otherwise, using ReplicatorG by itself (using Skeinforge) is ok. (Very few people tried to use Skeinforge to optimize their printing results because it was not written for human consumption!) Slic3r is very flexible. (Check out this short online tutorial. Or the full online reference manual.) One can set every imaginable parameters for 3D printing. As a result, it has a deeper learning curve. If you just want to do a quick print, then don t use it. Use MakerWare instead. If you want to produce a very good print, then learn how to use Slicer. There are a few parameters that must be set for TOM or Replicator-2. Once you re happy with your configurations, you can save them in Slic3r. Lastly, the easiest and the simplest way to slice your STL file is to use Makerbot s MakerWare. It is getting better and it produces reasonably good results with its default setting if you choose the correct printer (Thing-O-Matic or Replicator-2). It is designed to be child-friendly so it leaves many configurations hidden. Unfortunately, our TOM is running an older version of the Sailfish firmware, it doesn t work currently with the newer MakerWare directly. However, you still can use MakerWare to generate readable G-code (.gcode ), and then import it inside ReplicatorG for printing. Here are the printing parameters for Replicator-2. Plastics: PLA (default for Replicator-2) Layer height: 0.2mm (standard, 0.1mm for high resolution) Filament diameter: 1.75mm Nozzle diameter: 0.4mm Feed rate: 90 mm/s (if you want good quality, don't set it too fast!) Travel rate: 150 mm/s Build Platform temperature: N/A Extruder temperature: 225C In-fill: 10% (don't set it higher than 20%) Shell: 2 (or 1, in addition to the first shell) 5

7 For printing on the Replicator-2, a higher resolution 3D printer than TOM, we use MakerWare as well. We will generate a compressed G-code file (.x3g ) from STL files. After import (or add) one or more STL files, you choose Make, which will export the G-code into a file. You may choose uncompressed (.gcode ) or compressed (.x3g ) G-code files. Currently, we recommend to save the compressed G-code.x3g file onto an SD card if you use Replicator 2 for printing. Replicator-2 has an internal LCD display and a control panel. So, it doesn t need the ReplicatorG software to control it. (In the past, we used ReplicatorG to print directly over the USB cable to Replicator-2, but it is too cumbersome when we are printing a 10 hours job; so we have since switched to use printing from an SD card instead.) The Replicator 2 printer can only use a 2GB or smaller SD card; so don t use a larger capacity SD card. 6

8 SECTION 2 Preparation for Printing For printing on the Thing-O-Matic, the platform must be heated to 130C before printing. You may want to preheat the platform using the ReplicatorG s control panel if you are continuously printing many objects. Also, the platform must be calibrated so that the first layer gap is about 0.1mm between the extruder and the platform. You must do this manually. There is no automatic calibration procedure. If you want to change filament, you must manually heat the extruder to around 225C and then unload/retract the filament. There is a set screw above the extruder to press the ABS plastic against the feeder. You need to loosen it before you can remove the plastic filament. Reverse the procedure for loading the filament. Extrude the new filament a few seconds to make sure the loading process is successful and that any leftover plastic is flushed out. Printing on the Replicator 2 is a bit easier, but because the build platform is not heated, it takes a bit of practice to get the first layer to stick. We only use PLA plastic for Replicator 2. PLA can be printed without a heated platform. The factory build platform is made out of a 9mm thick acrylic, which warps slightly over time. We also have a piece of 9mm thick glass for printing. (Updated) We can only print PLA on Replicator 2, which uses an unheated build plate. Over the past year, we have tried several build plate preparation techniques: 1) the original factory Acrylic build plate; 2) glass with hairspray; 3) glass with 3M Blue tape (2090). 7

9 PLA sticks very well on Acrylic; sometimes, it sticks so well that you cannot remove the print without breaking the build plate or the print. So, we tried several techniques to improve or simplify the build plate preparation process. The most successful technique has been using 3M Blue Tape on glass. After applying a layer of Blue Tape, sand it lightly to remove its waxy surface, clean the surface with isopropyl alcohol, and it is ready for printing. Gap the initial Z-height to 0.09 or 0.1mm. PLA sticks reasonably well on Blue Tape. After each print, if you are gentle, you may be able to remove the print without breaking the tape. Just re-applying a new layer of tape if you break the tape. This technique works every time, but it is a bit time consuming to prepare. The 3M Blue Tape is the most expensive masking tape, thus not cheap over a long period of printing. (Recommended technique) The original factory Acrylic build plate works reasonably well except sometimes the print sticks so well that it is difficult to remove. So, Dr. Henry Thomas discussed this issue in his youtube video series about preparing build plate for his Replicator 2. His suggestion is that the easiest to use is the original factory Acrylic (9mm) build plate. To prevent the print sticking too well to the Acrylic build plate, he uses the following procedure to prepare his build plate: 1. Clean the build plate with isopropyl alcohol; 2. Apply a thin layer of olive oil; 3. Remove excess oil with isopropyl alcohol as much as possible. We have made two extra Acrylic build plates, each of which consists of two pieces of Acrylic (6mm plus 3mm) sheets. The 3mm sheet is lightly sanded to create a sand-blasted finish. We applied the same preparation procedure as above. For larger prints, the top 3mm sheet can be bent slightly to allow the print to be removed easily. Don t bend the 3mm sheet too much! It will break. So, be gentle! Just bend it enough so that the print can be lift with a spatula/scraper. All three acrylic build plates have similar thickness; so you don t need to recalibrate after switching these build plates. Gap it to around 0.09mm to 0.1mm if you have to re-calibrate the platform again. Good luck! 8