October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

Index

Tips on Schematics and Circuit Board Design p.2

2 D Methods p.4

3 D Methods p.7

Human Factors p.9

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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Tips on Schematics and Circuit Board Design

Schematics

Layout

o Organize components into logical groupings

o Utilize ports to minimize connecting wires

o Keep the schematic neat and uncluttered

o Use multiple sheets if possible

Components

o Source components early to ensure what you need is available

o Ensure the correct footprint is selected to match the components ordered

o Consult IC data sheets and application notes to ensure all peripheral components are included;

be aware that datasheets may contain errors – use your logic

Information

o Provide all the information necessary for someone to understand the circuit and to produce a

printed circuit board

o Label every component with the name and value

o Include an information block with project name, design version, designer’s name and other

pertinent information.

Produce a Bill of Materials

o This feature may be built into the software but if not , construct the BOM carefully, mindful of

the various footprints available for each component

o Include as much information as possible, such as preferred suppliers and product numbers, to

assist whomever will be responsible for ordering parts

PCBs

Layout

o Allow space to access components for testing or adjustment purposes (example – a

potentiometer)

o Allow space to access components for connections such as cable connectors, wires, tubes,

daughter boards etc.

o Keep AC and DC components separated on the board

o Clearly mark power connections – include the voltage if space allows

o Provide a ground plane on the bottom layer with as few power and signal traces as possible.

Ground planes can be added to the top as well – consult data sheet especially for RF

components which will have specific grounding and placement guidelines

Components

o Review the data sheet for recommendations on PCB layout – especially for RF components like

a blue tooth module

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o Consider the placement of the board in the enclosure – will the board fit in the enclosure once

the board is populated?

Information

o Identify all components on the PCB board

orientation of the printing should be kept to two directions

it is not necessary to include the values as these may change

keep it as uncluttered as possible

o Identify the board – leave space on the layout to include the board version and, the date,

project name, or any other relevant information

o Provide a board outline – A simple polygon on the silk layer will suffice to provide the PCB

production house with the information they need to layout your board. This outline can also be

used as a cutting guide. All copper should be 10mil inside the outline

Sending to a PCB production house

Create only the gerber files you need - some PCB production houses do not include bottom silk layers

View the gerber files using software such as GCPrevue if your software does not have this capability–

this will allow you to see exactly what the production house will see - a simple mistake may be

revealed

View the drill report – most production houses have a limit on drill hole sizes, if you exceed this

amount find holes of very similar sizes and combine them all into the larger of the sizes

Zip all the files together and include the following:

o Send a list of the file extensions either in the email or in a readme.txt file– each program

produces different file extensions and the production house should be given all the information

needed to produce a board – don’t make them guess. For example: .GTS = gerber top silk; .TSM

= top solder mask

o Include the file name which confirmation to the PCB production house that they have received

the intended files

DO

Save and save often. If you are working on a large cct, save a new file when significant changes are

made so that you may easily revert back to an older version if necessary – Save each file with a unique

name identifying the version.

Save older versions in a separate folder and rename them appropriately – ObsoleteProjectV1.

Have someone review your work, both schematic and PCB layout, it is easy to miss something simple

DO NOT

Do not send the wrong board version to the PCB production house; if you have multiple copies of a

PCB layout, document them well and do not keep them in the same folder

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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Do not assume the data sheet or schematic software is without error – we have found errors in

datasheets as well as the footprints provided by the PCB software

Do not send boards out on a Friday afternoon (or any afternoon for that matter) as it is better to leave

it until the following morning for one final review before sending it out; the PCB production house will

most likely not start production until the following afternoon - haste makes waste

Online Videos

Eagle Tutorial

http://www.youtube.com/watch?v=1AXwjZoyNno (there are many more in this series)

Create Gerber Files using Eagle

http://www.youtube.com/watch?v=B_SbQeF83XU

Surface Mount Solder Techniques

http://www.youtube.com/watch?v=b9FC9fAlfQE

http://www.youtube.com/watch?v=HRzPI6acg84

Surface mount soldering Play list

http://www.youtube.com/watch?list=PL1ECBCA7EA4BA9CD2&v=Ql6Vkw5wswU

Through-hole Soldering

http://www.youtube.com/watch?v=j1myNa2RpMc

De-soldering

http://www.youtube.com/watch?v=zjQf0ajBYmM

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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2D Machining Processes

Plasma Cutting

Plasma cutting is a process that is used to cut steel and other metals of different thicknesses (or sometimes

other materials) using a plasma torch. In this process, an inert gas (in some units, compressed air) is blown at

high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the

surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the metal being

cut and moves sufficiently fast to blow molten metal away from the cut.

Any electrically conductive metal can be cut. Including steel, aluminum, stainless steel, and copper.

Cutters are rated at the thickness a plasma cutter can cut at a rate of 10 inches/min. Softer metals like

aluminum and copper are de-rated.

160 mm is the maximum you can cut with a plasma cutter....this thickness requires power levels of 800 to

1000 Amps. On materials above 3" thickness an edge start is mandatory.....no piercing

http://www.hypertherm.com/en/Products/Mechanized_Plasma/Systems/HyPerformance_Plasma/hpr800xd.j

sp

Cutting a sprocket - 1 min 30 sec.

http://www.youtube.com/watch?v=FHUs_u27IpE&feature=plcp&context=C3923b64UDOEgsToPDskJtXG9gYh

0gSv-giyQZo10k

Waterjet cutting

WaterJet Cutting uses a mixture of water and fine garnet abrasive to cut materials ranging from aluminum to

Inconel (a super alloy) and rubber to plastic. Abrasive waterjet cutting mix is pressurized to 55,000 psi and

passed through a cutting head at speeds up to 1000 feet per second. This pressurized stream cuts a virtually

limitless variety of shapes and contours.

Waterjet cutting large stainless steel gears http://www.youtube.com/watch?v=d1YjqouRDVo

Laser Cutting

Laser cutting works by directing the output of a high-power laser, by computer, at the material to be cut. The

material then melts, burns, vaporizes away, or is blown away by a jet of gas, leaving an edge with a high-

quality surface finish. Industrial laser cutters are used to cut flat-sheet material as well as structural and piping

materials.

Laser cutting of various thicknesses – 1 min http://www.youtube.com/watch?v=gHjGfwf3Aeg

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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Electrical Discharge Machining

Electric discharge machining (EDM), sometimes colloquially also referred to as spark machining, spark eroding,

burning, die sinking or wire erosion,[1] is a manufacturing process whereby a desired shape is obtained using

electrical discharges (sparks). Material is removed from the workpiece by a series of rapidly recurring current

discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of

the electrodes is called the tool-electrode, or simply the ‘tool’ or ‘electrode’, while the other is called the

workpiece-electrode, or ‘workpiece’.

How Wire EDM Works – 2 min 26 sec. http://www.youtube.com/watch?v=pBueWfzb7P0

Waterjet Cutting in comparison to Plasma

Abrasive waterjet cutting provides a nicer edge finish

Abrasive waterjet cutting does not heat the part

Abrasive waterjet cutting can cut virtually any material

Abrasive waterjet cutting is more precise

Plasma is typically faster

Waterjet Cutting in comparison to Laser Cutting

Cutting can cut many materials that lasers cannot. (Reflective materials in particular, such as Aluminum and Copper.

Uniformity of material is not very important to Abrasive waterjet cutting.

Abrasive waterjet cutting does not heat your part. Thus there is no thermal distortion or hardening of the material.

Precision abrasive waterjet cutting can obtain about the same or higher tolerances than laser cutting (especially as thickness increases).

Abrasive waterjet cutting can machine thicker materials. How thick you can cut is a function of how long you are willing to wait. 2" (50mm) steel and 3" (76mm) aluminum is quite common. I heard of people doing up to 10" (250mm) steel, and 24" (600mm) thick glass with high horsepower systems. Once you get over 2" (50mm) thick it is very difficult to get precision, however. Lasers seem to have a maximum of 0.5" (12mm) - 0.75" (19mm).

Abrasive waterjet cutting is safer. No burnt fingers, no noxious fumes, and no fires. (You still have to keep those fingers out of the beam.)

Abrasive waterjet cutting is more environmentally friendly.

Abrasive waterjet cutting is capable of similar tolerances on thin parts, and better on parts thicker than .5"

Abrasive waterjet cutting does not lose much "focus" when cutting over uneven surfaces.

While laser cutting is often faster on thinner materials... o ...it may be cheaper and faster to simply buy two or three abrasive jet machining centers to do the same work o ...you can stack materials, so you are cutting multiple thin parts simultaneously. o ...you can run additional cutting heads in parallel on a single machine

Abrasive waterjet cutting does not create "scaly" edges, which makes it easier to make a high quality weld.

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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CNC Punch Press

Plasma

(Standard) Laser Waterjet EDM

General Pros

Ability to add bends, louvers

and other forming

operations, precise hole

diameters

Low machine cost High speed and low

cost in thinner stock

No HAZ, burrs, or dross. High

thickness capability. The ability

to trade off edge quality for cut

speed.

Very high accuracy,

ability to control taper.

General Cons Burrs Considerable edge

taper

Problems with high

reflectivity metals,

dross

More costly than laser in

thinner metals Expensive

Thickness

Capability (In

Steel)

3/16” 1” typical, up to a

maximum of 6 “ 1/2” – 3/4” 2-3” effectively, 8”-12” slowly 24”+

Heat Affected

Zone None Significant Significant None Very minor

Design issues

Allow for deburring and

nibbling marks. Keep

internal features away from

edges.

Allow for

significant edge

taper

Edges will be glass

hard if heat treatable

steel is used.

Minimize internal holes, or

allow for etching between

holes.

Minimize internal holes

New Machine

Cost

$7000 & Up $150,000 & up $100,000 & up $80,000 & up

Usual Accuracy +/- .005 +/- .015 +/- .005 +/- .005 +/- .001

Materials All metals, limited by

hardness All metals

Most metals, plexi-

glass, plastics, wood,

leather, fabric

All metals, including hardened.

Plastic, wood, glass, stone

All metals including

hardened. Cost

increases with melting

point.

Consumables Punch sharpening

Tips, nozzles,

gases,

compressed air

Gases, nozzles,

optics Water, garnet, nozzles

Wire, filters, wire

guides

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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3-D Manufacturing Process

Conventional Machining and Support Equipment

Lathes generally produce round parts such as shafts, bushings/collars, grooves and threads.

https://www.youtube.com/watch?v=n3QRquD_tFs

Milling machines generally produce parts with flat features such as faces, slots, shoulders, etc. and

they can also produce bores, holes patterns, etc.

Drill presses are generally used for drilling and tapping.

Brakes are used for bending sheet metal. https://www.youtube.com/watch?v=FCZQSGXsvw4

Shears are used to cut sheet metal.

CNC (Computer Numerical Control) Machining

CNC machines are automated equipment used to produce multiple and/or intricately contoured parts. Parts

can be produced by turning or milling material off the raw stock.

Turning Centres rotate the work piece while being held in a chuck. They produce various shapes

similarly to a lathe yet they can also produce unique features with live tooling.

https://www.youtube.com/watch?v=46aHPR4MQjk

Machining Centres hold the work piece in a vise or fixture and the cutting tool rotates. They produce

various shapes similarly to a milling machining as well as more complex profiles in multiple axis.

https://www.youtube.com/watch?v=8NatiYBitAI , https://www.youtube.com/watch?v=yBelt9lA2HY

and https://www.youtube.com/watch?v=2n7PICO3vyo

Software CNC equipment uses a CAM (computer-aided manufacturing) program to convert a CAD (computer-aided

design) drawing into software commands used to control a specific machine. We use MasterCam as our CAM

software to convert drawing from various CAD programs.

Build Process Due to the detailed part and tooling set-up, the time and skills required to produce components tend to be high. This process would only be used when other prototyping methods are not suitable for the project.

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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3-D Printing

FDM Fused Deposition Molding(FDM) is the process of building 3D CAD parts by layering plastic one slice at a time until the part is complete. The material we use is robust enough to use as a functional part. However there are some limitations to strength and finish. In general, build your walls and other features slightly bigger than what you would typically find on traditional injection molded parts.

https://www.youtube.com/watch?v=NXAhOEn8nXQ

https://www.youtube.com/watch?v=EWHR-5AKfd8

https://www.youtube.com/watch?v=82WXI9IGduM

Software We typically use Solidworks for designing our 3D parts but any software that can save the part as an .stl file will do. There can be problems with programs that use spline modeling such as Rhino. The .slt file is then processed in Insight, a program that orients, slices, adds support and defines a tool path for

the RPS.

Build Process The build envelope is 16 x 16 x 18. Multiple parts can be run at the same time. Build time will depend on the size and number of parts. Support material takes the same amount of time to build, so the more support needed the longer the part will take. Sometimes complexity will have an impact on build time. Removal of support may be done by hand and/or in an ultrasonic bath.

Finishing With time and patience an FDM part can be sanded, filled and painted so that it looks identical to an injection molded part. See the link for tips on finishing FDM parts. http://www.technimoldsistemi.com/upload/files/articoli/3/Stratasys-Painting_technimoldsistemi.com.pdf

October 1, 2015 [MAKE+ STUDENT FABRICATION ORIENTATION]

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Human Factors

1. Explanation of the process

Human Factors is concerned with the interactions among humans and other elements of a system in order to

optimize human well-being and overall system performance.

https:/www.hfes.org/web/AboutHFES/about.html

To design effectively, you need to understand:

Who is the user?

What are the users’ needs?

How are things currently done?

When, where and how will your intervention be used?

Do you understand the user experience?* What specific gap do you hope to fill? **

This information can help the design team at several different stages of the design cycle:

To explore feasibility of a project idea

To define requirements that will feed into design

To compare different products or design concepts

To evaluate how a concept, prototype or finished product meets end user needs (e.g. usability, performance, aesthetics, etc.)

To improve design (create recommendations/ requirements for future iterations)

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A number of different techniques can be employed to understand end user needs:

Focus groups/ Interviews

Expert review

Simulation

Site visits/ Observation

Biomechanical analysis

2. Usability

Usability relates to how easy it is to use a product to perform the prescribed tasks. Specifically,

effectiveness

efficiency

satisfaction Increasingly we are seeing usability tied to safety related standards in medical equipment design.

(CAN/CSA-C22.2 No. 60601-1-6; FDA Draft Guidance Document: Applying Human Factors and Usability

Engineering to Optimize Medical Device Design; ANSI/AAMI HE75:2009 Human Factors Engineering- Design of

Medical Devices)

3. Ergonomics

Ergonomics is the science of matching the task and the product to the user. Some things to consider include:

anthropometrics of users (weight, height, strength, hand size, etc.)

maximum forces to be exerted

how force will be applied

muscles and joints involved

user’s posture, body positioning, joint alignment

duration of exertion

repetitive motions

lighting, external environment Some useful resources can be found at http://www.ccohs.ca/oshanswers/ergonomics/

4. Function - Universal design

Universal design (UD) aims to create products or environments that are usable by everyone to the greatest

extent possible. The rationale behind UD is that many of the design features required by people with

disabilities were also useful for others and should be included in common practice. When principals of UD

applied correctly, they are virtually invisible.

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Principles of UD:

Equitable use (useful and marketable to people with diverse abilities; appealing to all, without stigmatizing)

Flexibility in use (accommodate a wide range of individual preferences and abilities e.g. left handed scissors)

Simple, intuitive to use

Perceptible information (effectively communicate necessary info to user)

Tolerance for error (minimize hazards and adverse consequences)

Low physical effort

Size and space for approach and use (including accommodating different sizes, grip, etc.)

5. Biomechanical Analysis

Biomechanical analysis can be used to measure the performance of users and/or their interactions with

different technologies. Some biomechanical assessment tools include Motion Capture systems, pressure and

force sensors, goniometers, as well as technologies to capture physiological parameters such as body

temperature, muscle movement, heart rate, and oxygen uptake.

The links below provide some more details on Motion Capture:

Vicon Motion Capture Basic Explanation:

https://www.youtube.com/watch?v=qgS1pwsHQIA

Sport Motion Capture:

https://www.youtube.com/watch?v=PW5F1Iy_gw4

* Image from: http://www.aternity.com/aternity-central/electronic-health-record-ehr-burrito-common-insights-ciohealth/ **Image from: the Cat in the Hat, Dr. Seuss