3D Model!

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By Mason Nguyen, Project Manager
Solid Works simulation by Vinh Kim

Solid works model:

In order to build a durable and low budget hexapod, resin molding would the primary component for our team to use.  The robot is developed based on a previous version which is focused on the straight-line walking. To enhance its ability to adapt to the terrain, each leg has three revolute joints driven by Power HD 1501 servos. Wasting no time, Vinh Kim our manufacturer started working hard on 3D initial design for our hexapod in Solid Works.  Our main priority we would focus on would be the hexapod shoulders. Both robots had the same dilemma where their legs bent forward while walking and ended up tumbling due to an enormous amount strain from the heavy body weight.

To correct that error, we will be limiting the amount of materials that going to be placed on the hexapod. Also, aluminum brackets will serve as a strong supporting pillar on the hexapod shoulders when operating.

Over the weekend, Vinh has been busy working on the Hexapod body design. Full 3D body assemble will be posting up later around the middle of this week.

3D Body:

 3dbody

Height and Width = 11 by 9.8
6 large holes is .30 in
26 small holes each .06 in

Femur:

 femur

Width = 4.05 in
Thickest = .276 in
Height = .95 in

2 large holes is .30 in

8 small holes each .06 in

Tibia:

 tibia

Height = 6.34 in
Width = 1.75 in
Thickest = .354 in
4 small holes each .06 in

Bracket:

brack

Height = 33 mm
Width = 54.18 mm

16 small holes each .06 in
Aluminum bracket to support the hexapod shoulders

This week goal is to assemble our 3D model!

Vinh Kim is working hard to create and assemble a perfect 3D model. We will have it by the end of this week.  

Meanwhile, Chau To our computer programmer continues working hard to program our servos with the edition of the Adafruit driver.

Tien Dang who is our communication engineer also lends the team a hand by assisting Chau with the programming and putting together our hexapod prototype.

Here is a video of our hexapod prototype where we demonstrating how the servos will rotate and operate.

Original Mendel Model

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By Anh Nguyen

ADVANTAGES:

  • Simple to build.
  • There are a lot of information, manual and video to help building.

            http://reprap.org/wiki/Mendel_Build_Manual

            http://www.youtube.com/watch?v=mpOZ1GNZmmU

  • Big print area, smaller machine footprint
  • Light and portable
  • The price is reasonable and within budget.

 

DISADVANTAGES:

  • The frame and the joint junctions are not stable in the x-axis. The head moves in the x-axis and it is heavy à causing the frame the move in the x-axis. This can cause a problem of precise printing.
  • It is hard to maintain. Have to remove a lot of things to change one detail. The electronic circuit is on top à difficult to reach some area under.
  • Required a lot of calibration when something goes wrong or needed to change.
  • A lot of wire strain. When the base moves, it creates the strain on the wire and the wire can be broken when using a lot.
  • 2 z-axis motor. Difficult to adjust both sides for the same amount. Moreover, the standard stepper motor is built for only 2A. The 2 motors use more than 2A, which heats the stepper motor is hot and can shut down for a few milliseconds and affect the precision of printing.
  • Hanging z-axis.
  • 1/2 COST
  • $520 – $600

 

Mendel90

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By Mevan Fernando

Mendel90 Build Manual:  http://reprap.org/wiki/Mendel90_Build_Manual#Getting_Your_Parts
More info: https://github.com/nophead/Mendel90
http://reprap.org/wiki/Mendel90_Buyers_Guide
http://www.thingiverse.com/tag:mendel90

Advantages

  • Designed by Nophead (Good parts/service available from Nophead, very detailed, high quality instruction manual, shared his design through his blog: http://hydraraptor.blogspot.com/2011/12/mendel90.html )
  • Sturdy structure means faster speeds in the x and y directions
  • Easy to assemble
  • Not a lot of calibration is required
  • Open frame design, allowing it to be worked on easily and mostly disassembled without falling apart
  • Ribbon cables are used to prevent cable tangling and friction
  • Less need for adjustment
  • Great reviews from Mendel90 owners

 Disadvantages

  • Critical hole dimension and spacing
  • The platform moves in y as well as z directions
  • MDF is the cheapest material that could be used to build the frame but changes in weather may cause it to expand or contract. Aluminum is a better choice but it’s more expensive (Materials that could be used for frame: MDF, polycarbonate, acrylic, Dibond, aluminium).

The budget for this project using Nopheads Mendel90 kit would be around $1100.

If we buy our own parts our budget would range from around $600-$800 depending if we could get some of our parts printed out and the material we use for the frame.

 

 

 

Laur3k-3D Printer by OpenBuilds

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By Omair Tariq

(Information on the Laur3K can be found here)

Advantages:

  • A lot of documentation (Pictures, Videos Parts list)
  • Without belts
  • Skechups of parts for printer also available

Disadvantages:

  • Print beds moves in y and z directions
  • Uses a lot of 3d printed pieces
  • Costs about $700. (Without printed parts, wiring, and controller)

How Does BioPrinting Work?

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By Omair Tariq, Systems and Test Engineer

How bioprinting works:

In order for cells to survive and grow, they need a certain environment. This environment is provided in gel scaffolds, referred to as biopaper in laymen’s term. There are several ways of 3D bioprinting. One of these ways is to print a layer of gel and then a layer of cell in a repetitive manner until the desired structure is obtained. Another method of 3-D bioprinting is to first print a gel scaffold and then facilitate cell growth in the gel scaffold by injecting in cells.

There are various types of gels that can be used as biopaper to meet this purpose: agar, agarose , polyacrylamide gel etc. Due to a lack of availability of funds and equipment, it will be very difficult for us to verify at the cellular level whether the cells have grown correctly or not. Therefore, this semester, we will concentrate on utilizing the 3D bioprinter for the generation of 3D gel scaffolds. 

bio

 

Organovo NovoGen MMX Bioprinter

Untitled-1

 

HowUntitled-1

MendelMax 2.0

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By Ali Etezadkhah, Project Manager

 Advantages:

  • Open and rigid frame
  • Can be built using hand tools or CNC machine
  • Extruded and flat plate aluminum
  • Linear rail-based x and y axes with smooth and quiet operation and less maintenance
  • Faster printing possible due to increased rigidity
  • Second generation solves problems with the first generation
  • Heavy and stable
  • Aesthetically pleasing

 Disadvantages:

  • Expensive at around $1500
  • Single-axis head and single-axis bed means the bed is not stationary
  • Heavy and difficult to move around

More information at:

http://reprap.org/wiki/MendelMax_2

http://www.mendelmax.com/

This model would be a good choice for our project due to its resolution, speed, and printing area.  However, the printing bed moves along y and z directions.  It’s a mature model with plenty of documentation online from the creator as well as multiple forums dedicated to it and previous models.  There aren’t many cons to this printer except the price.  At around $1500, it is more than our proposed budget.

Rover Level 1 Requirements

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By Maxwell Nguyen

Level 1 Requirements:

Our top mission requirements are derived from the specifications of the standard Arxterra Rosco.  The requirements will include speed, power consumption, cost, and time.

Speed:
Our rover is expected to move at a speed of 0.200277 m/s.  This is calculated using the standard wheel diameter of 45mm and RPM of the motor. 

Wheel diameter = 45 mm

 wheel

3D model of wheel

 

Motor Specs:
120:1 Plastic Gearmotor 90-Degree Output

 motorspic

Free-run speed @ 6V: 85 rpm

Velocity calculation:
Radius = d/2
R = 0.045/2
R = 0.0225 mm
Circumference = 2*pi*r
C = 2*pi*0.0225
C = 0.141372 m

Velocity = RPM*C

V = (85 rot * 0.141372 m)/60 sec
V = 0.200277 m/s

Cost:
Must have a lower cost compared to the standard RoSco of $284.13.  The BOM for the standard RoSco can be found in the two links below.  The first one lists the parts and links to find the parts while the second link provides a sum of all the costs of each part.

Parts list and where to purchase them.

Rover Projected Cost List

Time:
The rover must be completed by May 12.  This takes into account CSULB’s final exam schedule and deadline for the project.

Acetone Vapor Bath

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By Mustafa Alkhulaitit – Project Manager

After researching some of the techniques for smoothing the surface of a printed object, we made a conclusion that acetone vapor bath is one of the simplest ways for achieving the desired goal. Up to this point, we do not have the 3D printer to perform this experiment, so some simple equipment and materials will be used for now.

The Process:
The way the acetone vapor bath works is very simple. First of all, the reason of this process is to get rid of the horizontal lines of a printed object.

BLOGFig.1 (2)
Fig.1

A smoother surface is a lot better looking than those horizontal lines, and smoother surface means stronger shine and therefore, higher resolution. The acetone bath works only on ABS plastic.

BlLOGig2
Fig.2

The process is as follows:

Screenshot (15)

The time to leave any object in the bath varies because bigger objects may need extended times.

The Tools:

  • Acetone – when heated to a boiling state, it melts out the plastic
  • Electric Hot plate – easier to maintain heat
  • Aluminum foil – so object doesn’t stick to the base
  • Glass jar or glass teapot – to put the object inside
  • Food can – make base out of any aluminum food can so object doesn’t have direct contact with acetone; a hook can also be made out of an aluminum hanger

 1_HOTPLAT1

 

blog2)

 

blog3

 

LAST

Cost Schedule Version 1.0

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By Mustafa Alkhulaitit – Project Manager

 

#

Part

Price Range

1.

Heated Bed Upgrade

$30 – $50

2.

All Metal Hot End

$100

3.

Surface Toning

TBD

4.

LCD Panel

$50 – $70

5.

2x NEMA 17 Stepper-Motor

$20

6.

2x M2.5 x 12mm Bolts

$0.64

7.

M2.5 Nuts

$0.60

8.

TowerPro SG-90 Mini Servo

$3.49

9.

OMRON SS-5 Micro switch

$1.75
 

 

 Total = $270
       


The costs above are only an estimate. The table will more likely change in the future, especially as we start to actually build, test, and design the 3D printer and the needed parts.

Dual Extruder Head 3D Printer

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By Mustafa Alkhulaitit – Project Manager

 One of our main objectives is to add an additional extruder head to the 3D printer. The dual extruder upgrade will remove any shape restrictions. There are many shapes that the single extruder head will not be able to print. The dual extruder head will allow us to print using dissolvable support structures such as HIPS and PVA. Having multiple extruders allows us to have multiple filaments ‘piped in’ and ready to be used whenever the object being printed requires them, and this is where the saved time comes from. Another advantage of having dual extruders is the ability to print in two different colors by using multiple filaments.

Fig.1

Besides the advantage of dual extruders, there is a limitation for dual extruders. According to “3D printer prices” “The limitations of multiple extruders come as a result of the different extruders currently sharing the same print head. Since each extruder is locked to one another and unable to move independently, more material could only be printed if the object required a symmetrical object to be printed the exact distance apart from the original, as the two extruders are positioned.” Until the extruders can move independently, the benefits of duel extruders come only from having multiple materials readily available.

The dual extruders when operated by the RAMPS card and the Arduino Mega 2560 will result in smoother, higher quality prints. The RAMPS card is dual extruder ready and will not need additional shields or boards. The attached designs and pictures show how the design is going to look like for the dual extruders.

Our plan for the dual extruder is to make a duplicate copy of the existing extruder head. The stepper motor will not be attached to the nozzle head directly because this will take space and will make heads heavy. Instead, the stepper motors will be held in a specific way, as can be seen in Fig.3; fig.2 shows how stepper motors are put on most designs, which is not the correct way of placing them. This method makes the extruder heads heavier and a lot slower than what Fig.3 demonstrate.

Fig.2

Fig.2

 

9.IMG_0704_preview_featured
Fig.3

There will be a more detailed study regarding dual extruder heads and whether we are going to use support material or an extra color. The future blog will also include more specifications regarding the new dual head.