Weekly Progress

Hi,

We're filling out weekly progress reports as part of our university project requirements. I thought I'd post them here too, since reading it might help others with their project planning.

Reporting period: Jan 04 to Jan 10


1.) Is your project on schedule? No
Mechanical assembly of the Reprap is nearly complete, but electronics and testing has not begun. This is expected to take about one week. Schedule had ambitiously estimated that test printing would be conducted this week.

2.) What did your group members accomplish during the past week?
- Prepared parts for Reprap 3D printer (drilling and tapping holes, cutting rods, sanding parts).
- Began mechanical assembly of Reprap 3D printer. Mechanical assembly is now about 90% complete. Printer X, Y, and Z axes are built, awaiting the addition of timing belts and a replacement shaft coupler. Extruder construction and electrical system assembly has not yet begun.

3.) What problems, if any, did you encounter?
- Printed part holes were slightly undersized, requiring them to be drilled out (although this brought the advantage of creating a smoother bore). This made the assembly more labour-intensive and time-consuming than expected. As well, several parts did not fit together without significant sanding and filing (we later learned that boiling water can be used to soften these parts to help them fit).
- Due to out-of-date documentation, we drilled out some diagonal-bracket holes which were meant to be interference fits, making the parts loose. This problem was fixed by bandsawing a slot in these parts to create a split ring, which when tightened produces a strong grip. We believe this split-ring design is superior to the original interference fit, and so we will release it to the Reprap community as an improvement to the Darwin design.

- We were lacking a part required to splice the Z-belt, and one of the shaft couplers was misaligned. On Saturday, Bing and Jacob visited Wade and obtained the belt-splicing jig, as well as a replacement shaft coupler. Therefore, assuming the replacement coupler functions correctly, Cartesian assembly is expected to be completed this Monday Jan 11th. Electrical system construction and testing has not yet begun, so the project is behind schedule.
- Extruder components, ordered one month ago, have not yet arrived. We are concerned that they may be delayed at the border due to heightened Olympic security. If these do not arrive on time, replacements will need to be machined on the premises. This is do-able, but will consume additional time.

4.) What are your main goals for the week?

Construction of the extruder and electronics, and testing of the Reprap system.


5.) How much time did each member spend on project work in the past week?
[This figure excludes time spent in during winter break, from Dec 28 to Jan 04, estimated at an additional 20 hours per team member].
Mo Chen / 18 hours
Jacob Bayless / 18 hours
Bing Dai / 18 hours

1.) Is your project on schedule? No
Mechanical assembly of the Reprap is complete. Extruder, electronics, and testing must be finished before a test print can be conducted.

2.) What did your group members accomplish during the past week?
- Completed XYZ mechanical assembly; fitting and splicing belts as needed.
- Tested and corrected printer axes. They can now move smoothly under the motor's own power. Resolved an issue that was causing Z axis to bind.
- Machined two new custom brass shaft couplers, to replace critical printed parts with tighter-tolerance versions.
- Machined a brass knurled shaft attachment for the extruder stepper motor, to provide pinchwheel grip.
- Built an MDF baseplate to mount control electronics.
- Began assembling extruder.
- Began mounting electronics.

3.) What problems, if any, did you encounter?
- Z-axis was binding at first, making it impossible to drive even with the high-torque stepper motor. The problem was identified to be loose nuts, which slipped from their intended position and self-tightened against a bracket, locking the axes in place. The nuts were tightened properly in their correct location. With additional minor adjustments, the Z-axis could move smoothly.
- The Polycarbonate printing bed was found to be slightly warped (bowed shape). It is not under load, so the warping must be inherent in the sheet itself. Bed flatness is very important to achieving a successful print. Adding reinforcement struts under the bed may be able to resolve the situation; this is presently unknown.
- We will need to make reinforcement plates/flanges to flatten the Z-bed. This will require appropriate materials, and possibly waterjetting time.

4.) What are your main goals for the week?

Finishing construction of the extruder and electronics, and testing of the Reprap system.


5.) How much time did each member spend on project work in the past week?

Mo Chen / 19 hours
Jacob Bayless / 19 hours
Bing Dai / 19 hours

1.) Is your project on schedule? No
Reprap is complete. Software issues are delaying extruder testing; these should be resolved shortly.
Perhaps it's time to revise the schedule?

2.) What did your group members accomplish during the past week?
- Completed assembly of electrical and mechanical parts, as well as mounting PCBs and opto-endstops.
- Created new opto flags of the correct size
- Began debugging software problems
- Calibrated X,Y,Z axes and thermistor


3.) What problems, if any, did you encounter?
- We're using the extruder v.2 (pinch-wheel extruder), which is not set up to work with the software we were planning to use (ReplicatorG). We're now switching to the alternate software that supports the pinchwheel (Reprap Host), but it has failed to compile because we're using a thermistor to measure extruder temperature instead of a thermocouple. Currently we're consulting about how to fix this issue.
- Upon switching to the Reprap Host software, the Z-axis once again failed to move. This should be easy to resolve by adjusting in-software constants.

4.) What are your main goals for the week?
- Finalize mechanical design and materials requirements for wire print head
- Resolve current software problems

5.) How much time did each member spend on project work in the past week?

Mo Chen / 16 hours
Jacob Bayless / 16 hours
Bing Dai / 16 hours

1.) Is your project on schedule? No
The extruder and Z-bed are able to follow G-code instructions; heater can reach controlled temperature and melt filament. However, extruder cannot currently drive filament properly.

2.) What did your group members accomplish during the past week?
- Began documentation of project on Reprap wiki under the name "SpoolHead"
- Drove a fan and CD motor using the MOSFET chips on the extruder controller
- Tested the working temperature range of PLA filament
- Debugged Reprap Host software; can now successfully control printing with it
- Evaluated new options for new extruder mechanical system, such as a spiral-slot cutting system
- Created new 3D model of proposed print head (attached)
- Successfully tested printing models from G-code without extrusion

3.) What problems, if any, did you encounter?
- Extruder stepper motor does not have enough torque to drive the filament under the current setup. Knurled shaft fitting increases the shaft radius, reducing the force provided by the motor. Wade Bortz has designed a new geared extruder to boost the torque; he plans to visit on Monday to see if this will help resolve the problem.
- Knurling the shaft directly, or ordering a splined stepper motor, may also resolve the problem.
- The issue of cutting the wire appears problematic. A fully satisfactory solution has yet to be found.
- Due perhaps to overzealous application of insulation material, or overly high temperatures, extruder filament frequently jammed. Insulation was rearranged to provide a thermal vent, and testing temperatures were reduced.

4.) What are your main goals for the week?
- Resolve extruder motor issues and print a plastic part, preferably before Wednesday
- Finalize the mechanical design of the new print head

5.) How much time did each member spend on project work in the past week?

Mo Chen / 16 hours
Jacob Bayless / 19 hours
Bing Dai / 16 hours

1.) Is your project on schedule? No.
The new extruder design has the mechanical capability to drive filament properly. However, due to software issues with the firmware, the extruder stepper motor is not able to follow G-code instructions and drive filament at the desired speed.

2.) What did your group members accomplish during the past week?
- Mounted the extruder stepper motor on a new rack designed by Wade. Wade's extruder uses printed gears to achieve excellent torque. The new design extruded plastic stream at a fast and stable flow rate following testing code.
- Updated the wire extruder design in preparation for the presentation, and again following discussions with Bernhard on Friday.
- Designed a waterjettable mounting system for Wade's extruder to let it be used with the wire print head in parallel. (Wade's extruder is larger than the original).
- Replaced an accidentally broken plastic Y-opto-endstop with one made from thin metal.


3.) What problems, if any, did you encounter?
- Our stepper-driven plastic extruder still isn't working properly. The geared extruder can run, but very slowly - this is a software limitation. We're can drive it quickly when we run a simple "go forwards!" loop, which gives very good results for extrusion. But we can't yet do this while printing from G-code, because the speed-adjustment settings apparently do nothing. We've made some headway in resolving this issue at the firmware level, but it's still holding us back.

4.) What are your main goals for the week?
- Resolve extruder firmware issue and print a part.
- Update solid model to include Bernhard's wire cutter design.

5.) How much time did each member spend on project work in the past week?

Mo Chen / 16 hours
Bing Dai/ 16 hours
Jacob Bayless / 12 hours

1) Is your project on schedule? No.
With some minor changes to the software, the machine printed tested parts for the first time. Subsequent refinements improved the print quality. However, the extruder heater broke down later the week.

2) What did your group members accomplish during the past week?
- Software is able to read G-code/.stl files and drive extruder based on a stepper motor.
- We identified 243 degrees Celcius (at the point of measurement) as an excellent temperature for printing. Unfortunately the value will likely be different when the extruder is rebuilt.

3) What problems, if any, did you encounter?
- "Midterm week" pulled a lot of time away from working on the project.
- As mentioned, the extruder broke down just a day after it was finally made to work perfectly; the likely culprit is extreme heat melting the solder causing it to open-circuit.
- We aren't reporting our successful test prints as a milestone yet, due to this.

4) What are your main goals for the week?
- Finish the electronics and software design for wire head.
- Finish the mechanical design for the wire head and begin building it.
- Repair the plastic extruder and print a new object.

5) How much time did each member spend on project work in the past week?
Mo Chen / 7 hours
Bing Dai / 7 hours
Jacob Bayless - 7 hours

solder? you don't solder your heater, you crimp it, then stick some spaghetti tubing over the wire. The rear half of pin header plugs make a good crimp wrapper, and I've also seen high temperature ceramic terminal blocks locally.

Since the temperature sensor is designed to run at a similar temperature, it should be crimped too, however a tiny amount of solder that won't go anywhere when molten can help the electrical connection. Whatever's left after a solder sucker or wick is probably a good amount.

[objects.reprap.org] may help.

Standard 60/40 tin/lead solder melts at about 180 celsius, and lead-free solder melts at 210-240 depending on the alloy. Also, it's almost impossible to get solder to actually stick to nichrome, so soldering the heater is totally useless on two separate fronts.

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Wooden Mendel
Teacup Firmware

Yes... This is what we're doing now. Because we bought our extruder nozzle from Makerbot, we were following the Makerbot instructions:
[wiki.makerbot.com]

The connection was crimped as well as soldered, but failed anyway. I've rebuilt the heater now, and I hope the new, crimp-only connection lasts much longer.

1) Is your project on schedule? No.
This week, we unsuccessfully attempted to repair the extruder, trying several new schemes. It appears that the Reprap's plastic extruder design is less reliable than we were led to believe initially. A waterjettable redesign of the wire print head was also begun, and strong inroads were made into controlling multiple extruders with the firmware.

2) What did your group members accomplish during the past week?
- Developed and tested several theories as to why the extruder is failing.
- Machined a new extruder based on these tests which should function properly.
- Set up the firmware to run most of the outputs from two extruder boards independently.
- Made improvements to the wire print head mechanical design
- Continued documenting the development on the SpoolHead wiki entry
- Got in contact with additional members of the Vancouver RepRapping community, including Enrique (authour of slicing software Skeinforge), increasing our community support base
- Got in contact with Dany Lipsker, inventor of a technology related to the SpoolHead.

3) What problems, if any, did you encounter?
- A second extruder burnout, and failure of the third extruder to extrude plastic.
- The stepper motor cannot currently be controlled independently on the second print head. They both spin at the same time, regardless of the commands. This is likely a firmware error. We will evaluate between writing a fix for the firmware, or reverting to the pencil-driven print head.
- Mo got sick early in the week and was unable to work for a large part of the time.

4) What are your main goals for the week?
- Repair the plastic extruder and print a new object.
- Finish the waterjettable spoolhead design, and cut it out
- Correct the dual-extruder software, or alternatively design a pencil-powered version

5) How much time did each member spend on project work in the past week?
Mo Chen / 18 hours
Bing Dai / 40 hours
Jacob Bayless / 40 hours

1.) Is your project on schedule? No
We made great leaps this week in catching up. The Reprap is now able to print plastic parts. The team has changed focus to the wire-embedding module.

2.) What did your group members accomplish during the past week?
- The extruder jamming problem was solved, allowing for proper prints.
- Printing quality was improved after software tuning.
- The software and electronics for wire-embedding were implemented and/or tested.
- The pencil extruder prototype design was finalized, and parts were cut out on the waterjet.

3.) What problems, if any, did you encounter?
- We are still unable to drive two stepper motor extruders simultaneously.
- The Z bed "wobble" is reducing print quality. As it moves up or down, the layers are displaced in X and Y. This could be corrected in software or hardware, but we will wait and see if it becomes a major issue.

4.) What are your main goals for the week?
- Finishing building the wire-embedding module
- Controlling it with the electronics
- Present our progress at the project fair

5.) How much time did each member spend on project work in the past week?
Bing / 35 hours
Jacob / 35 hours
Mo / 35 hours

1.) Is your project on schedule? No
This week was mainly spent catching up in other courses.

2.) What did your group members accomplish during the past week?
- Identified and corrected an error that would start the print job in the middle, with expectedly poor results
- Machined additional parts for the spoolhead extruder

3.) What problems, if any, did you encounter?
- Very difficult to insert 0.3mm copper wire into the pencil, although steel wire was inserted successfully. Using a narrow feeder tube as a bowden cable, the wire can be inserted; however, this traps the bowden cable into the assembly, which can cause the pencil to jam. This could be corrected by properly mounting the tube, or replacing the tube with a u-shaped channel.
- The stainless steel barrel has been extremely tough to machine, and resulted in several broken drills so far as it work hardens. New purpose-made drills have been purchased which might resolve this.
- Little time was available this week to work on the project because of catch-up work for other courses, as well as the project fair.
- Bench-top experiments to narrow down design parameters with the wire extruder have not been conducted yet; these are crucial.

4.) What are your main goals for the week?
- Finish and mount the first wire extruder prototype
- Write G-code for the test parts
- Conduct bench top experiments to test elements of the wire system


5.) How much time did each member spend on project work in the past week?

Mo Chen / 6 hours
Jacob Bayless / 11 hours
Bing Dai / 6 hours

1.) Is your project on schedule? No
But we're rapidly gaining ground!

2.) What did your group members accomplish during the past week?
- Machined three extruder tips, each one different to test different variables
- Machined and successfully tested the wire cutter by hand
- Tested the heat-wirebonding concept, first with a rough and successful proof of concept, demonstrating the extreme strength of the thermoplastic bond
- Repeated this test with a variety of wire types, including bare copper wire, magnet wire, and piano wire
- Then tested with increasing sophistication using the heated tips "in-situ" to manually deposit wire in a printed part
- Documented tests and hypotheses publicly at [spoolhead.blogspot.com]

3.) What problems, if any, did you encounter?
- Attempts to use radiation and convection heating have been unsuccessful, so we have for now altered our plan to use contact heating
- The 0.3mm pencil has been only marginally successful at feeding wire. We are therefore switching to a more robust 0.5mm pencil; however, this one requires more force to click. We may need to use either a stronger solenoid or a servo-motor-cam system to click it.

4.) What are your main goals for the week?

- Design a new mount on the SpoolHead for a 0.5mm pencil and servo actuator
- Test the wire cutter with a solenoid

5.) How much time did each member spend on project work in the past week?

Mo Chen / 11 hours
Jacob Bayless / 13 hours
Bing Dai / 13 hours

1.) Is your project on schedule? No

2.) What did your group members accomplish during the past week?
- Machined the alternative (sliding, non-rotating) cutter piece to test out
- Successfully tested new methods of bonding the wire along its XY path (not just at the beginning point) and documented these
- Implemented servo control with the extruder controller electronics
- Designed a simple, waterjettable (and printable) servo mount
- Designed and printed a mount for the 0.5mm pencil

3.) What problems, if any, did you encounter?
- Machining the cutter parts was highly labour-intensive and required precision tools. A more easily implemented method will need to be developed in the future.
- The new 0.5mm pencil has different dimensions than the previous one, and requires a modified setup for clicking
- Play in the machine's Z axis is causing minor problems. Wade has suggested a way to repair this.
- The servo is indeed going to be much slower at clicking than the solenoid, so it would be impractical in a finished product. It should serve as a reasonable proof-of-concept.

4.) What are your main goals for the week?

- Finish the new clicker design for the 0.5mm pencil

5.) How much time did each member spend on project work in the past week?

Mo Chen / 14 hours
Jacob Bayless / 14 hours
Bing Dai / 20 hours

Reporting period: Mar 22 to Mar 28


1.) Is your project on schedule? Yes(!)

2.) What did your group members accomplish during the past week?
- Interfaced with the extruder board's servo controller, and successfully tested wire-feeding using the servo-clicking method;
- Finished writing G-code for robotic control of the test print;
- Printed our first 'wired' parts using G-code, achieving one of our milestones.

3.) What problems, if any, did you encounter?
- The stiffness of the spoolhead mount has been found to be insufficient for the side loads it takes. For now we can use a software correction to improve quality.
- We opted not to mount Wade's extruder side-by-side with the spoolhead, to avoid a heavy cantilevered load on the XY carriage.
- During plastic printing this week, the printer suffered unprecedented vibrations, causing screws to loosen (this in turn was found to have been caused by loose screws).

4.) What are your main goals for the week?

To test our solenoid cutting concepts to see if we can also get automated wire cutting.

5.) How much time did each member spend on project work in the past week?

Mo Chen / 15 hours
Jacob Bayless / 9 hours
Bing Dai / 15 hours

Reporting period: Mar 29 to Apr 04


1.) Is your project on schedule? Yes


2.) What did your group members accomplish during the past week?
- Wrote a Matlab script to accelerate the creation of G-code for wire parts
- Successfully developed a method for printing a spiral, demonstrating that curves can be printed using guides
- Tested the second cutting mechanism, and found it ineffective. The first (rotating cutter) has not been tested yet.

3.) What problems, if any, did you encounter?
- We found that the "sliding" cutter couldn't work, because the extruder mounting was not stiff enough to resist the pull forces. So when we pulled on the solenoid, the entire tip deflected instead of the wire being cut. The rotating cutter looks like the best method, although we could also return to the idea of using scissors too, since heating the wire is easier than we expected.

4.) What are your main goals for the week?

To submit the final report.


5.) How much time did each member spend on project work in the past week?

Mo Chen / 15 hours
Jacob Bayless / 8 hours
Bing Dai / 8 hours