Fab@Home:Using Model 2
From Fab @ Home
Fab@Home Model 2 Quick Start User Guide
Step 1: Make Connection
1.1 Plug in the power cable of the snap motor.
1.2 Plug the USB cable from an available USB port on your PC to the USB connector on the bottom of the Snap Hub located at the top right of the machine.
1.3 Turn on the snap hub with the switch located on the top after making sure you have plugged in all the motors as described in Fab@Home:Cables.
confirmation of connection?
Step 2: Install Software
2.1 If this is the first time you have connected your PC to the Fab@Home, you will need to install the control software. Follow the directions to install both the FabStudio and Interpreter components. The necessary drivers for the snap hub should automatically install.
Step 3: Run Application and initialize hardware
3.1 Start the Fab@Home interpreter by opening FAB2.exe. 3.2 Click initialize and load the printer configuration file. 3.3 If hardware and configuration files correctly loaded, the fields with values for the position of each motor will no longer be grayed out.
Step 4: Verify Motion
4.1 Using the up/down arrows at the right edges of the motor position fields, test that all of the axes are working. You should see the corresponding motors moving in the correct direction and amount.
Step 5: Define Tool/Material
Currently, the tool configuration files for the Model 2 are the same as those of the Model 1. This is subject to change. Therefore, sections 5 and 6 use the FabStudio application to configure tools and import STL geometries.
5.1 If you are using a material and/or syringe needle/tip combination that you have not used before, you will need to define a new .tool settings file and add the tool to the .printer printer configuration file.
The following info should get you started: When you are setting up your new materials, it’s good to start from a tool file for a material that is similar to the one you are working with. Save a copy with an appropriate descriptive name, then edit the file: Change the comment at the top Change the name and description fields to match your material and syringe tip You should then tune certain parameters so that you get desirable results when building some small test part (e.g. a small thin rectangle).
The main parameters to tune are:
DESCRIPTION is for you to keep a brief note of distinctive features of the tool and material.
TIPDIAM is the internal diameter in mm of the actual syringe needle or tip you have selected to use, and is used by the software in estimating the volume of material required to build a path, layer, or complete object.
The PATHWIDTH and PATHHEIGHT (both in mm) tell the path planning algorithms the distance between the horizontal slices/layers of your model (PATHHEIGHT) and the separation between the paths within a layer (PATHWIDTH). Start out by making these both roughly the internal diameter of your needle/tip. For runny materials, the PATHHEIGHT should be made smaller and the PATHWIDTH larger based on your intuition.
PUSHOUT and SUCKBACK are both delays for the starting and stopping of the syringe motor relative to the motion along a path. They are defined in seconds. When both values are positive, the syringe motor will start driving the syringe plunger to extrude material PUSHOUT seconds before the XY motors begin to traverse the current path, and the syringe motor will transition to full reverse SUCKBACK seconds before the XY motors reach the end of their current path to stop the flow of material from the syringe. The goal is to adjust both of these parameters so that your material deposition starts and stops precisely at the beginning and end of the desired path without pooling, dripping or stopping too soon.
DEPOSITIONRATE (a dimensionless ratio) determines the linear distance moved by the syringe tool plunger per linear distance (along a deposition path) moved by the X and Y axes – basically how much material to deposit per unit length of a tool path. A high DEPOSITIONRATE will try to push a large amount of material out along the path, tending to make the deposited strand of material wider, taller, and typically messier. A small DEPOSITIONRATE will tend to push insufficient material from the syringe, and the strand of material will typically be broken, tend to adhere to the syringe tip rather than the part or build surface. Try to adjust the DEPOSITIONRATE until the flow of material leaves the tip of the syringe at the same rate that the XY motors traverse along the path. Ideally, DEPOSITIONRATE should simply be (Cross-section area of Syringe Needle)/(Cross-section area of Syringe Piston) = ((Needle ID)/(Piston OD))^2. It is recommended that you start by calculating this value, then adjust it slightly as necessary.
CLEARANCE is how far the table will move down when the XY-carriage is moving from the end of the current path to the start of the next one. Small clearance values will result in faster build times, but may increase the chances of material dripping onto undesirable locations of the object being built. We recommend 2mm for the clearance.
PATHSPEED is the speed of motion along deposition paths. Large path speed will result in faster build times, but increased chance of position errors, end hence lower quality parts. Speeds below 12mm/s are generally ok, but on more complicated parts with fine details, speeds of 5-8mm/s may be necessary to achieve good results.
PAUSEPATHS is the number of deposition paths the machine will complete before automatically moving to the safe position to calibrate (check for position errors). Using a lower value of pausepaths will improve build quality, especially for tall objects, and can somewhat offset the negative consequences of using higher path speeds. We have found PAUSEPATHS between 10 and 60 to reasonable.
Starting with version 17a of the Fab@Home application, you can update several of the tool parameters “online” - meaning while a build is underway. This enables you to start building an object with your best guess for parameters, then tune some of them while the build is underway, so you can see the effect quickly. To change parameters online, simply edit the .tool file and save it, then in the FabStudio Application, use “Tool”->”Refresh Parameters”. You should see a change on the very next path (after completion of the current path). The parameters that can be changed online in this fashion are PUSHOUT, SUCKBACK, DEPOSITIONRATE, CLEARANCE, PATHSPEED, and PAUSEPATHS. Changes to the PATHWIDTH and PATHHEIGHT parameters will not affect a build that is already underway – they only affect the processing (path planning) steps, prior to the commencement of fabrication.
Step 6: Create .fab files
6.1 This section will use the the FabStudio application, which was the standard program for the Model 1 in order to create a fab file which merges tool configurations and 3D model data.
6.2 Load the tool configuration file created in the above step.
6.3 Using the "Model->Import Geometry..." menu item, navigate to the .STL file(s) which describe(s) the geometry of the part you would like to build, and open the file(s). You can select up to 5 files to open simultaneously, which simplifies building objects composed of many parts.
6.4 The geometry should be displayed on the virtual build surface in the graphical display of the application.
6.5 The geometry can be translated, rotated, and resized as desired using the "Model->Translate", "Model->Rotate", and "Model->Scale" menu items, respectively. It is generally recommended that you always select all (CTRL-A, or "Edit->Select All") of the geometry (all parts) before manipulating them with these tools in order to ensure that relationships between multiple parts are preserved.
6.6 To set materials properties, bring up the Chunk Properties dialog box by double clicking on the part geometry, or by using the "Model->Properties..." menu item.
6.7 This dialog allows you to tell the Fab@Home system what material and tool settings you would like to use to build each of the parts you have imported, what priority you would like to use to build each part, and also to modify the color and transparency of each part in the graphical display. Use the "Part Name" dropdown list to select the part to be modified, then select a "Tool/Material" to build that part, and/or a color, and/or a transparency, and/or a "Priority" - then hit "Apply" or "OK" (use "Apply" if you will be making other changes to other parts).
An aside on "Priority": sometimes, in particular when building objects which will have multiple materials in them, it is desirable to build certain parts of the geometry to their full height before building other parts. Parts which have been assigned a higher priority will be built to their full height before parts of lower priority are even started - regardless of their relative positions in space! This can reduce the number of tool changes required to build a multi-material object enormously, and can also allow you to build a mold out of one material, then have the machine go back down into the mold and deposit other materials into it. Creatively splitting your object into multiple parts and giving them carefully selected priorities can greatly reduce build times and enable you to build much more complicated multi-material objects. It is strongly recommended that you test out the priority feature in emulation mode ("Printer->Emulate Hardware" checked) so that you can observe the effects before trying it on the physical hardware. One obvious limitation to the use of priorities is that objects must be supported while they are built, and the machine cannot reach underneath an object after it is built - for example, when building a stack of two identical blocks, assigning a higher priority to the top block will result in a failed build - the machine will attempt to deposit material in mid-air to build the top block (resulting in a pile of garbage on the table), then try to build the bottom block (adding to the garbage on the table).
Note that the "Part Name" dropdown list can be used to select a part for other manipulation (scale, translation, etc.) when that part is difficult to select via mouse clicking - just open the "Model->Properties...", select the "Part Name", and then hit "Cancel" and the named part should be selected.
6.8 Save the project as a .fab file for use by the interpreter.
Step 7: Inserting/Removing Syringes and Changing Materials
7.0 Prepare your syringe barrels, pistons, and tips 7.1 At this point, you should load a syringe barrel with the material you are going to use to build the particular part. See Material Handling Tips for some suggestions on how to do this.
7.2 Whether or not a syringe is currently in the tool, you need to retract the tool shaft to provide clearance to insert/remove a syringe. If a syringe is inserted, use the handle on top of the tool motor shaft to unthread the shaft from the syringe piston until it
7.3 Now either by manually turning the motor shaft, or by adjusting the tool position in the Fab@Home Interpreter, retract the motor shaft until the lower shaft end is clear of the syringe barrel and near the bottom of the motor body.
7.4 To remove a syringe, slide it straight upward until the top of the syringe hits the underside of the plate on which the motor body is mounted. Tilt the tip of the syringe out toward you, and unsnap the syringe barrel from the upper restraint.
7.5 Insert the new syringe by snapping the upper part of the barrel into the upper restraint of the tool body, then sliding the syringe as high as possible, then tilt the tip away from you into the tool body, and slide the syringe downward until seated all of the way down into the tip restraint.
7.6 Insert the motor shaft by manually turning it or by using the Jog Tool dialog box until the lower tip of the shaft is in contact with the syringe piston.
7.7 Manually turn the motor shaft until the tip of the shaft threads into the nut inside of the syringe piston.
Step 8: Cover Build Surface
8.1 Many materials will adhere to the build surface, so it is recommended that you cover the build surface with a thin disposable or washable material, such as waxed paper, aluminum foil, plastic wrap, etc. We recommend Cut-Rite waxed paper, which can be clamped to the table using large "binder" type paper clips, or Glad Press-N-Seal plastic wrap, as it is slightly stretchy, but adheres to the Z-table, so that you can stretch all of the wrinkles out and secure it without using adhesive tape. Waxed paper makes removing your part from the table much easier, as most materials will not adhere to it, while some materials (epoxy and silicone) may be difficult to peel off of the plastic wrap.
Step 9: Set Positions
9.1 The Build Origin
- The Build Origin defines the starting point for deposition of material - your part will be built starting at this location. The build origin is up to you, but it is recommended that you use the center of the build surface, then carefully adjust the z-height until the syringe tip just touches the build surface. Using this location for the origin will cause parts to be built more or less where they are positioned in the FabStudio application - you can translate your model on the virtual build surface.
9.2 Set the build origin by moving the axes to the position described above, and clicking Reset Position in the Interpreter to set the origin.
Step 10. Print
10.1 Load the .fab file created in Section 6.
10.2 Ensure the correct build tools are selected in the drop-down menus to the right of each tool Bay. Bay 0 is left, Bay 1 is right.
10.3 Execute. Monitor the print progress. If material runs low, pause the print, refill the syringe in the same way as before, and reinsert the syringe.