Fab@Home:Model 2 Chassis

From Fab @ Home

Welcome to the Fab@Home Model 2 Chassis Overview

This page contains instructions for final assembly of the individual sub-assemblies within the standard Fab@Home Model II:

1. Base
2. Z-Carriage

1. Optional: Replace with Extended Z-Carriage for improved stability. NOTE: current revision needs a riser to be used with the Dremel tool because the tip will not reach the tray. The printing tools, foam cutting tools, are all fine. Z-Carriage Extended

1. Bridge and carriage
2. Deposition tool

First visit each of the above sub-pages in order and follow the directions on each to assemble the sub assemblies.

NOTE: do not use excessive force to fit acrylic parts together - the material is liable to crack. This may happen if the acrylic used has high variability in thickness. File down overly tight interfaces until the fit is correct, but not too loose. Damage, however, can be repaired with cyanoacrylate adhesives (i.e. superglue).

If you are looking for CAD files of the chassis for cutting your own, or places that will cut the chassis parts for you, please visit the Fab@Home:Model 2 Bill of Materials. If you are able to open Solidworks or Parasolid CAD files and are assembling your own unit, they may prove useful for additional visualization.

Putting it all together

1. Chassis + Z table
   1. Place Z-Axis sub assembly between the top and bottom plates of the chassis.
   2. Screw Z axis pillow blocks to the top and bottom plates with 6-32 screws.
      
2. Bridge + carriage
   1. Place the bridge+carriage assembly between the front and back plates of the chassis above the top plate
   2. Screw the pillow blocks to the front and back plates of the chassis.
      
3. Mounting the tool
   1. Slide the quick mount tool into the carriage from the top, and secure with a 6-32 thumbscrew. If the tool will not slide into place easily, be sure that none of the nuts securing the Carriage front plate or Tool back plate are protruding - push them as far into the acrylic as possible. Use washers on the screws on the tool mount in order to get the correct spacing if necessary - this is where variance in the acrylic thickness becomes an issue.
      
4. Attach rubber feet and level the chassis. Leveling is important in ensuring the axes work smoothly without binding.
   
5. Belts
   1. Peform a final check for smooth operation of the axes. If problems are encountered, loosen the screws securing the pillow blocks and the mounting plates for the linear bearings associated with the problem axis until the source of any problem is identified. Re-tighten carefully, inserting shim washers if necessary.
   2. Thread the Z axis belt, the two X axis belts, and the Y axis belts around the corresponding pulleys. Tighten, and lock into place under the corresponding belt clamps. See Model 2 Commissioning for details.
   3. For smooth motion, both sides of each belt loop needs to be taut. Each of the X axis drive belts need to be in approximately equal tension. If the Z axis has problems moving upwards, it is most likely the case that the front side of the belt below the Z axis is too loose - tighten it by moving the belt ends closer together under the clamps.
6. Insert electronics
   1. Insert snap hub. Ensure that the small switch next to the USB port is set to the "Pass Thru" setting.
      
   2. Attach power and usb cables
   3. Attach ethernet cables to motors.