1. Purchase replacement parts:
   1. Core Tube (buy one) – http://store.makerbot.com/machined-core-tube-for-mk6-1-75-mm.html
   2. Replacement PTFE Tube (no longer carried by Makerbot) – McMaster-Carr #8547K23 – (1/4″ OD by 1/8″ ID ) order 1′ length.  Will need to be machined and beveled to the proper dimensions (to fit inside the 1/4″ ID Thermal Barrier Tube and guide 3mm ABS filament).
   3. Motors (buy two) – http://store.makerbot.com/nema-17-stepper-motor.html
   4. XY Motor Pulleys (buy two) – http://store.makerbot.com/xy-motor-pulley-for-5mm-shaft.html
2. Print and install Heated Build Platform Strain Relief (Makerbot #2 has one of these already)
3. Remove Automated Build Platform and replace with Heated Build Platform.   ABP does not work well for raftless printing.

Makerbot #2 (tag #6776)

General

1. Construct a spool handler.
2. Further calibration of printing process (such as leveling the X/Y table, further tuning Skeinforge settings)

Another trick to getting an object to adhere to the build surface is to make sure that the initial extrusion (which the gcode generated by ReplicatorG refers to as an “anchor”) does not become a blob that the extruder nozzle drags around the platform during the first few layers of a build.

From the time of its first testing, Makerbot #2 head never positioned the extruder nozzle above the silicon wiper at the beginning of a build, so it was always necessary to snag the anchor with a pencil or pliers to make sure it didn’t get pulled along by the nozzle.

The “start” section of the gcode that ReplicatorG generates contained some notes about this — and after tweaking a very short gcode file to discover the proper coordinates of the wiper, the next big challenge appeared: which file to modify.  The file which ReplicatorG notes in the comments of the gcode it generates indicated one file, but after combing through a bunch of start.gcode files, it was ultimately determined that the correct start.gcode  file was [ReplicatorG install path]\machines\thingomatic\start+HBP+Stepstruder.gcode

If ReplicatorG is installed on a different workstation, start+HBP+Stepstruder.zip should be unzipped and copied into the above file path to properly home and wipe Makerbot #2.

Thing-O-Matic #1 (4391 )

• Stepstruder Mk6+ (configured for 3mm filament)
• Motherboard v2.5 (with Arduino 2560) – firmware v3.1
• Automated Build Platform
• Extruder Controller board v3.6 – firmware v3.1
• Spindle kit (missing feed tube)
• Calibration
  • Servo voltages
• Modifications
  • Stepper shafts ground to accommodate pulleys (probably need to replace steppers since pulleys don’t spin true)
  • Location of Z- and A-axis control boards swapped on mounting board to accommodated shipped cable lengths.
• Issues
  • Extruder jamming – originally, unit was assembled with 3mm filament capability.  Tried to run 1.75mm filament through it before realizing this, which jammed the extruder.  After several cycles of taking apart and reassembling the extruder, I rebuilt the unit with 3mm capability and “repaired” the tip of the  PTFE tube that guides the filament through the heater.  Ultimately, we should order replacements for both of the filament tubes.

Thing-O-Matic #2 (tag 6776) — operational

• Strepstruder Mk 7 (using 1.75mm filament)
• Heated Build Platform
• Motherboard v2.5 (with Arduino 2560) – firmware v3.1
• Extruder Controller board v3.6 – firmware v3.1
• Calibration
  • Servo voltages
• Modifications
  • Left side cutout for power supply modified to accommodate Makerbot’s change in power supply part geometry.
  • Heated Build Platform Strain Relief to prevent damage to HBP cables.

I suggested we search for “Arduino NG SPI” and we found a thread in the Arduino forums about this issue. To rectify the problem, I removed the pin 13 LED from both of her Arduino NG boards and SPI started working properly.

Sewing Cubby
One leftover piece of plywood was used to make Kelly’s sewing organizer. She also wanted a cubby system to store some of her batting and yarn.

We started off with some sketches — first exploring possible features of the unit

and then deciding how big we could make it given the available materials.

I fleshed out the design in Google Sketchup so Kelly could get a sense of the proportions and then built it. All joints are butt joints attached with 2″ coarse-thread wood screws.

Speaker Stands
Since days after we moved into our current apartment, our speakers have been perched atop cubes of taped-together CD jewel cases. This helped to eliminate some of the unpleasant boominess, but I’ve never been satisfied with the sound in the room. Months ago, I tried some experiments and found I liked the sound better when the speakers were elevated to ear height while I was seated on the couch. I didn’t think it would be too difficult to make speaker stands; I just didn’t get around to doing it until now.

Height and stability were the most important considerations in my design, so I tried to work with those parameters before considering whether I had enough leftover plywood to actually build the design.

After completing the design, I took stock of my remaining plywood and found I was very short of the material my design required. I considered making the stands shorter, but wasn’t really satisfied with the idea, so I let the design sit for a few days and then realized that by making the uprights thinner, I could still keep the height I wanted.

I revised the design and then began building.

I uploaded the model to the Sketchup 3D Warehouse, so you can download it if you like.

I may post this to Instructables one of these days. I already added captions to all of the pictures before uploading them to my Picasa web album. Unfortunately, I couldn’t find an easy way to get the captions show up on this page without hand-editing the HTML.

One of my goals for the summer was to learn how to user Sketchup. Here’s a first sketch of the old room layout.

Once I got the hang of using Sketchup’s “inference engine,” things started getting easier. Here’s the design of my hutch as well as a side table I made out of a recycled desk.

Here are a few phots of the process.

Since force sensing resistors from Interlink Electronics are expensive ($5-6/each) and also because I couldn’t see how the fragile FSRs would fit into the holes we planned to use, I wanted to find a better solution.

I discovered it was possible to create FSRs out of wire and plastic wrap. Others have used conductive foam and wire mesh. Reading about linear position sensors also gave some insights.

I took 22 gauge wire from the physcomp lab, stripped it, and bent it back and forth to mimic the “fingers” on the FSRs I purchased from Interlink. After making two wire finger pieces, I wrapped one in seven layers of plastic wrap. I place the second set of wire fingers on the outside of the package and wrapped it into the existing package. My first few tests seemed very promising. When no pressure was applied to the package, the resistance was infinite. When I squashed the package, the resistance dropped down to about 10K.

The next trick was to try to duplicate this behavior on the end of a PVC pipe. We first tried applying the plastic wrap/wire packages around the end of the PVC pipe. The results were less encouraging than my initial experiments.

The homemade sensors were unreliable: either the sensor package was too tightly squashed between the PVC and the surrounding hole (and gave no resistance) or it was too loose and no amoung of bending the pole caused a reading.