Provided: 1.3, 1.5 and 2 mm hex wrenches. Not Provided: Small flat head screw driver, pliers/adjustable. wrench.

Transcription

1 Note: These instructions are a work in progress, and DualStrusion is intended only for bleeding-edge experimenters. The MakerBot Stepstruder MK7 is the first extruder for the MakerBot Thing-O-Matic to be capable of easy mounting in a dual-head configuration and the use of multiple materials in one print. This awesome leap forward opens the doors to many new experimental capabilities, like objects of more than one solid color, objects with special properties, or even support material for objects with previously impossible overhangs. Building the Extruders: If you are starting with an existing MK7 extruder as per standard MK7 Assembly Instructions, you will want to disconnect its wiring and unbolt it from the mounting plate. It will not be otherwise changed, and can be considered a completed left hand-side head. Just follow the instructions for assembling the right hand-side head. If you are starting out from a dual-head kit or two single MK7 kits, follow along with all the instructions below. Provided: 1.3, 1.5 and 2 mm hex wrenches. Not Provided: Small flat head screw driver, pliers/adjustable wrench. The main assemblies here are these four. 2x Hot End: Nozzle, Heater Block, Barrel, Bar Mount, Bolt, Heater Core, Thermocouple, Ceramic Tape, Kapton Tape

2 2x Cooling block: Fan, Heatsink, Themostat, Spacers, Long Bolts 2x Drive system: Stepper Motor, Knurled Pulley, Setscrew, Molded Drive Block, Delrin Plunger, Rubber and Metal Washers 1x Extruder mount: Mounting

3 Panel, Spacers, Thumb Screw You need two M5x20 bolts and two M5 thumb screw caps. Using pliers squeeze each bolt into a cap.

4 Be careful not to damage the threads. Squeeze the bolt head into the cap to ensure a secure fit. Tip: Two pliers can be used at the same time. We recommend you use pliers with long handles, for best leverage. You should have two M5x20 thumb

5 screws. You need your two stepper motors, drive gears, two M3 set screws, both long stepper leads, and the small 1.3 mm hex wrench. First, disconnect the existing motor cable. Place the drive gear over the motor shaft. Place a piece of paper between the drive gear and motor to create a small gap.

6 Tighten the set screw against the flat of the motor shaft. If the set screw is not perfectly centered on the flat but is lower on the shaft, continue with the assembly but double and triple-check alignment when attaching the drive blocks. Then you can attach the longer cable we ve supplied, and your motor should be ready to go. Repeat this process for the second motor. You need the two stepper motor assemblies, two drive block front panels, two drive block back panels, two Delrin plungers, four M3x18 flat head bolts, four rubber washers, six metal washers, and a 1.5 mm hex key.

7 Place the plastic and metal washers on the Delrin plunger as shown. Place the drive block back panel on the motor with the cable facing left for the left hand-side extruder, and right for the right hand-side extruder. For the left hand-side extruder, place the plunger in the right slot. On the left hand-side extruder place the plunger in the left slot. Place the drive block front

8 on the assembly. Place the M3x18 bolts in the holes and tighten. Ensure your assembly appears as shown. Ensure good alignment between the filament channel and the MK7 drive gear. Assemble the bar mounts and thermal barriers You need two bar mounts, two thermal barrier tubes, two M6 nuts, and the supplied wrench.

9 Orient the bar mount such that the chamfered edges face you and the horizontal holes are close to the top. At this point you should designate the left and right versions, as they will not be assembled the same. For the left hand-side extruder, thread the thermal barrier into the right hole. For the right hand-side extruder, thread the barrier into the left hole. This will position the nozzles close together when bolted to the mount plate. Loosely thread the M6 nut onto the thermal barrier. thermal barrier until it is flush with the M6 nut. Finger tighten. Turn the Grip the top M6 nut with the wrench and tighten against the

10 bar mount. Check that your assembly looks like this. The lip of the barrel should be just barely poking up, but no threads should be showing. Assemble the thermal cores and nozzles You need two nozzles, two thermal cores, and 2.5 mm hex key. Thread the nozzle into the side with the small M3 hole. Place the hex key through the thermal core. This will give you a good grip. Grip the nozzle with pliers. Tighten the nozzle

11 against the thermal core. Ensure your assembly looks like this. Repeat for the second nozzle. they need not be identical, but the nozzles should be of very similar length. Assemble the mount plate and bar mount assemblies You will need the mount plate, M6x10 bolt, M6 nut, both bar mount assemblies, and pliers. Thread the M6 nut onto the thermal barrier. Leave a several

12 millimeter gap. Thread the M6 bolt into the bar mount. Leave a several millimeter gap. Place the mount plate in front of you with the double notch on your left. For the left hand-side bar, position the barrier on the left side of the double notch. The right hand-side bar uses the farthest-right notches. Check the image to ensure correct orientation. Slip the mount plate into the gap between the bolt head and bar mount. Ensure your assembly appears as shown.

13 Use the wrench to tighten the M6 bolt. Finger-tighten the M6 nut. Avoid rotating the bar mount assemblies while tightening. The two bar mounts should be as close to parallel as possible. Ensure your assembly appears as shown. Secure the thermal core assemblies You need the mount plate assembly, left and right thermal core assemblies, wrench, and 2.5 mm hex key. On both heads: thread the thermal core onto the thermal barrier. Finger-tighten without accidentally rotating the thermal

14 barrier. Place the large hex key into the thermal core for good grip. Hold the top M6 nut with the wrench. Tighten the thermal core against the thermal barrier. Be aware that if the nozzle is not on tight enough, it may be unscrewed accidentally. To be sure the thermal cores are rotated on the shaft correctly, loosen the top M6 nut against the mounting bar, rotate the barrel to the desired orientation (keeping note of how much barrel protrudes from the nut), and then rotate the nut to tighten against the thermal core. Loosening against the mounting bar means we will not loosen the connection from the barrel to the thermal core, and tightening against the heater core will not make the barrel rotate when we tighten the M6 nut. This assembly is identical on both extruders. Place the M3x45 bolts in the fan as shown. Note the orientation of the wires and label. Place the spacers on the bolts as

15 shown. Place the thermostat and heat sink on the bolts as shown. Place the mount bar on the bolts as shown. Gently flip the stack over, and place onto the motor and filament drive block. Tighten the bolts. Tip: Aligning the bolts into the motor's holes before tightening them

16 down makes the process easier. You need both extruder assemblies, two cartridge heaters, two thermocouples, two M3x5 bolts, two M3 set screws, two M3 washers, and a 2.5 mm hex key. For each head, place the cartridge heater in the thermal core with the wires toward the rear of the extruder. Secure with an M3 set screw. Insulate the thermocouples with a single layer of kapton tape over the metal tip. Secure the thermocouple against the thermal core with the M3x5 bolt and M3 washer as shown. The kapton tape will electrically insulate it from the extruder, as two uninsulated thermocouples will interfere with each other. From a length of ceramic tape, measure and cut a 3-inch segment.

17 Wrap the ceramic tape with a layer of Kapton tape. This makes it easier to work with. Cut a 1cm slot into the center of the segment, and cut the "legs" out of one of the sides. The center hole allows the nozzle and cartridge heater set screw to be accessed. Slide the uncut end of the insulation under the M6 bolt head until it touches the barrel. Hold it against the heater block with two short

18 strips of Kapton tape. bottom, and tape the legs back to the body when they pass the barrel. Wrap the insulation around the Mount the thermostat to the side of the heater block opposed side from the heater hole using two or three wraps of Kapton tape. The position is important, because if it is mounted right next to the heater it will trigger the cutoff below printing temperature. The leads should exit the back of the assembly as shown. You need a completed extruder set, two M5x22 thumb screw bolts, and two M5 nuts. Insert the thumb nuts up through the mounting holes in the Z-Platform, and hold them in place while adding the half-inch spacer. Tip: Tape or extra hands/fingers may be helpful to keep the bolts from slipping out.

19 Lower the extruder mounting plate onto the two bolts, and finger-tighten the nuts. Once secured, use the thumbscrews and get the mounting plate bolted on nice and securely. Ensure your assembly appears as shown. Wipers are needed during the Thing-o-Matic tool changes and purges, to eliminate extra plastic building up at the tip of the inactive nozzle and being rubbed onto the printed object. The design for the wipers is not finalized, but currently consists or two small silicone L-shapes, one bolted to each of the back corners of the HBP. The ABP is not supported, due to the protruding drive gear mechanism reducing the movement range of the X axis. If you are starting with a pair of silicone wipers used with the ABP originally, you will need to do some trimming. The wipers start out 10mm tall, and need to be reduced to between 5 and 7. This is because the MK7 nozzle is not as long as previous nozzles, and while that allows for a greater Z-axis range for taller builds, it also means that there is less room between the nozzle and the X platform. The original size wipers will hit the platform when printing the first few layers, and potentially push the nozzle out of alignment. The extruders will be using separate toolhead indexes for the software to call them. The lefthand-side extruder will be "Toolhead A" and use a machine index of 1, and the righthand-side extruder will be

20 "Toolhead B," with a machine index of 0. Be sure that none of Extruder 1's wires are attached to Extruder 0's controller board, or the printer will be very confused (as will you). Before changing anything in the existing Thing-O-Matic's electronics bay, power it on and connect to your machine. Use the "set toolhead index" menu item under "Machine" to set the existing single extruder to index 1. Once the update is confirmed, disconnect from the machine, and upload the latest firmware for first the motherboard, and then the extruder controllers. Then power off the machine and unplug the USB and power cables. Tip: It may be easier to completely remove and re-install the Thing-O-Matic electronics wiring when installing a second head on an existing machine, and it helps reduce confusion with which wires go where. The standard installation for the Thing-O-Matic's electronics places the X and Z controllers in the back two extruder mounts, and the Y and A controllers in the front right and front left respectively. With the addition of a second extruder, we will change this slightly to give the stepper harness the maximum available length. [Insert Image of electronics bay with two ECs and five SCs] Unplug the existing wiring from the front two stepper controllers, and then mount the additional extruder controller in the front mounting spot using long nylon spacers to stand it up off the board. This lets the CAT5e cable clear the stepper power or stepper port. [closeup image of second extruder controller mounted in forward right-hand spot] Install the additional stepper controller in the front far-left spot, or whatever open spot is available using the provided M3 bolts, nuts, and nylon spacers. [Image of all front stepper controller mounted] Pass all of the left extruder s cables through the back right corner hole and connect it to the extruder controller in the back right (EC1).All of the right extruder s cables should go through the front right corner hole and connect it to the extruder controller in the front right (EC0). The standard stepper wiring harness will not reach from stepper controller B to the righthand-side extruder, so we have substituted a Z-stepper wiring harness. The heated build platform s wires should go through the back right wiring hole and connect to controller 1, exactly as they would in standard configuration.

21 Wire everything else up as in the standard configuration. The power supply may not be able to feed more devices, so Molex Y-splitters have been provided to help get power to the new boards. Tip: the extruder steppers can share a splitter, as only one is active at a time. The extruder controllers would ideally not share the same line to the power supply, because they add the greatest load. If you haven't already, set the potentiometer values on your stepper driver board as shown here. Keep in mind that the MK7 ships with a Moons Stepper, and the REF voltage should be between and volts. You'll also need to recalibrate the Thing-O-Matic height as decribed here. This video has step-by-step instructions on the process as well: [youtube width="640" height="390"] /watch?v=yvqailfanau[/youtube] When it is time to render an STL into gcode for printing, you must choose one of the MK7 specific profiles. Replicator G contains a separate profile for ABS and the experimental PLA and PVA plastics. Next, under Print-o-Matic, we will enter reasonable settings for the MK7.

22 Layer heights of between 0.32 and 0.27 should be possible right out of the box; make sure that your filament diameter is set correctly for your 1.75mm stock. Configure infill and shells as you see fit. The nozzle and drive gear diameter should be set as shown. Take note of the newly added option under the extruder tab; the box for "extruder" lets you choose which head the generated GCode will be assigned to. The default is usually set to the right head, so be careful to pay attention to which you choose, and what plastics are loaded into the machine. Next up, designing and printing for multiple heads!

23 This page details experimental DualStrusion with a customized Thing-O-Matic. For information on printing in two materials on a Dual Stepstruder MK8 Replicator, see the Replicator DualStrusion page. Note that some material on this page will refer to an older version of the ReplicatorG software. Multiple head extrusion is now possible, but it is not ready for general or production use. Don t expect to turn your bot on and be able to print with multiple heads without spending time troubleshooting brand-new issues. We re just figuring this out now, and we re inviting you, the community to get involved. While it s very exciting, it also means that our technical support crew might not be able to give you all the answers you need because this is the edge of the unknown! Multiple print-head technology allows for printed objects with features in different colors and materials. Multiple colors enable much greater detail in a print, or the highlighting of a single component in an assembly. Multiple materials provide for much more complex structures in the print, such as support material that can be easily removed, or features that take advantage of a difference in physical properties -- for example a support structure for an otherwise impossible to print complex shape. To get ready for DualStrusion, you ll need to do a few things: Get all the additional parts you need for a Dual-Extruder setup Build your DualStrusion kit Prepare your designs for DualStrusion, using two.stl files that match up Merge the designs together into one gcode-enabled file. Print it! The script built into ReplicatorG operates by iterating through two separate and independently generated GCode files, and combines the layers they describe into a single GCode file. Other data is pulled from Skeinforge comments to make sure the heads are able to support different material properties, and no layers get skipped over. While the benefits to dual extrusion are really great, creating objects that can utilize both tool heads is also a complex process. Here we illustrate best practices and explain how to design for best results. Here s what you need for a working DualStusion setup for Thing-O-Matic: A second Stepstruder MK7, with an additional stepper driver A second extruder controller board for temperature control A few spacers to make wiring your second extruder board a bit easier. Once those show up, you ll have everything you need to get going! This is a bit of a long step, so there s a separate page dedicated to the build process. Basically, you ll be building two complete MK7 Stepstruders ; one in the same configuration as with a single-extruder, and one in a mirrored setup. Then you ll attach both extruders to a single mount plate. You ll want more detail than that, though, so check it out here!

24 Before you can go ahead and use the DualStrusion features in ReplicatorG, you ll need to set one of your extruders as Toolhead 1. If you don t do this, then you ll get an error message when you try to connect to your bot with a dual-extruder driver. To do this, connect only the extruder controller that you want to set as Toolhead 1. If you leave both extruders connected, you ll set the toolhead index for both of the extruders at once -- which won t help. Once you have the proper extruder connected, click the on the Set Toolhead Index... option in the Machine menu. Then set the number to 1 and click Set Index. Now you should be set to get started with the amazing frontiers of DualStrusion! Requirements for Design Normally, the STL filetype used for 3D printing does not have any kind of support for multiple objects or different materials. This is because an STL simply describes a list of triangles that make up the 3D model -- it does not have any other information about the objects these triangles form. However, most 3D modeling tools do allow for creating numerous objects, each with separately defined colors, textures, and in some cases physical descriptions such as material. Therefore it is not a limitation of the creation tools, but the tools intermediate to actual printing. Until a new standard is in place, we will design using the current one. To get around the limitations of the STL filetype, we will create separate STLs for the features of each separate property, like color or material. To align the STL files in the same space, we design the two parts at the same time, as an assembly. Even though the completed print may be a single object, we want to keep the models that make it up separate until the actual printing. Most 3D design programs honor the relative position of an assembly when exporting it as an STL file, so an object placed off center will remain off center when exported. If the program you are using does not, or you need to reposition the exported STL later, you will need to add some reference elements to allow you to reposition both STLs the same way. One way to do this is to add an extra feature that will be invisible to Skeinforge, but defines the space into which the models will be placed when processed into GCode. This shape can look like anything, but it is very convenient to simply create a very flat cylindrical "plate" on which the objects rest. The cylinder has its center aligned to the center of the object,

25 and a radius equal to the farthest measurement from the center. This shape ensures that for any two shapes you can simply center the resulting STL, and it will be where you need it to be in order to print. This extra feature is not always neccessary, but can be very helpful in certain situations. Note: you will need ReplicatorG version 0027 or later to access these features. To use the two tool heads with your two STL files, we will use the brand-new dualstrusion menu. First, make sure you have the "Thing-O-Matic with Dual MK7" driver selected. Without this driver active, the software will be unable to process the files. From the Gcode Menu in the menu bar of Replicator G, choose the very last item, "Merge.stl for Dual Extrusion (experimental)." This will bring up the interface for combining objects into the single gcode needed to run. Here we will select the files to be used for Extruder A and Extruder B (left and right respectively). If you want to swap the files chosen for any reason, you can use the Switch Toolheads button for that. Lastly, choose a directory and name for the completed gcode to be saved to. The combinations possible are as follows Two STL files Two Gcode Files One STL, and one Gcode An STL will offer options for setting the Skeinforge profile, and an Gcode file will be read directly. This means you do not need to re-process the STLs if you need to make changes to start/end.gcode or to the tool change or machine settings. It will re-combine the gcode directly. This can also be used, in theory, to put two independent prints into the same job. The settings for using the default start.gcode and end.gcode will replace the versions found in either of the original files with a known-good pair. These files are read from the "DualStrusion_Snippets" folder in the same directory as Replicator G. When all files are selected, the Merge button will start the process for combining the files designated. For any STL file you have selected you will be presented a window to choose the skein settings to process it into gcode with. Note that the title of the window will tell you which head you are choosing settings for. If you are using heads with different materials loaded, you will need to be sure that the settings apply correctly. Note: you will have to generate gcode for the first toolhead (left), and then generate the gcode for the second toolhead(right). The

26 progress windows will be placed on top of another - you can drag one of the progress windows away to see that status of the other. In this case, we are using the default MK7 ABS profile. Be sure to enable Print-o-Matic and apply the correct settings for your extruder. These are the default settings for the MK7. If you are seeing more plastic than expected, you can raise the filament diameter value. In this particular case, the setting listed under the "Extruder" tab for setting the head will do nothing, because it will be overwritten by the merge process. Once all settings are checked, simply press "Generate Gcode," and you will either be presented with a window for the second head (if you chose two STLs) or the process will begin to run the files through skein forge and then merge them. The resulting merged Gcode will open up in the main Replicator G window when the process completes. If nothing happens, check the console at the bottom for errors. It may be useful to look over the generated gcode to be sure correct files were used. Mac users may use the program "Pleasant 3D." The last step is to check the generated gcode. if you have already measured the correct offsets for your nozzles but have not saved them into the start.gcode inside "DualStrusion_Snippets," you can write them directly into the generated gcode. If not, then you should first print a dual-head calibration object and measure the difference from the "perfect" offsets that the software will initially assume. The lines you need to edit or add will begin with the G10 command, and should be in the first few lines of the file. The markup is very simple, and simply define an X Y Z difference from the machine's absolute center (between the nozzles). On one of the R&D bots, the code looks like this: G10 P1 X16.55 Y0 Z-0.3 G10 P2 X Y0 Z-0.3 If you need to make changes, save your

27 edits to the start.gcode file, and the merge script will use these from then onwards. Sometimes, you ll still want to just print using a single extruder head. To do that, use the option called Swap Toolhead in GCode within the GCode menu. Note that this will change all toolhead entries in your generated GCode -- if you do this with GCode that s been generated for DualStrusion, it will do the same, which will make it a single-extruder print.