Week 3 Day 1

 This week we move to electronics design and fabrication.
Today we started with electronics production. The goal was to fabricate a pcb from an already existing design. We use roland modela to fabricate the PCB.

 Assignment: to fabricate a version of fabISP using Roland modela and fab modules.

 Process
We downloaded the the following designs.
http://fab.cba.mit.edu/content/projects/fabisp/fabisp.png
http://fab.cba.mit.edu/content/projects/fabisp/fabispdim.png
Make sure most of the area is covered by double sided tape. We used the white  double sided tape instead of the transparent scotch tape. There are some advantages for using a white double sided tape. One is it has a larger area and it will be easier for us to cover the area. This makes sure that all areas of the pcb stuck to the base and are flat. Make sure there are no bubbles if you find some air bubbles remove them.
If the bubbles are at the edge it can be pushed to the edge, If it is in too much inside, puncture it and rub it flat using the shiny side of the double side tape paper.
We need to mount a sacrificial layer first. On top of this layer we place the layer we want to mill. It is recommended that the sacrificial layer is stuck such that the plastic side is facing up. This plastic layer is much easier to be milled if the tool plunges into it.
While sticking the pcb to be milled use same guidlines as to secure the sacrificial layer namely to properly covering it with double sided tape and making sure it remains bubble free.
Here you can either use scotch tape on regular intervals of 10 to 15 mm across the pcb base or the white tape to secure the PCB for milling. We used the white double sided tape to secure the entire area. This wasnt perfect and after a while(two days) the corners loose adhesion and rise up, which caused some milling problems,hence I'd like to try with scotch tape once.

A nicely aligned and secured arrangement looks like the picture here.



Removing and securing the bits: be careful removing or fixing the bits. Hold it in a way that it doesn't drop. 1/64 inch bit is very delicate and susceptible to breaking.

Sometimes you might need to Rotate png to place it on you board depending on the space available to be cut. You need to note that rotating using a normal image viewer will not preserve the size information. It mostly will look the same but would have scaled. We should resize it when this happens therefore, make sure to note the original size of the png image when it gets loaded in fabmodules. When you upload a rotated image use the old information to scale it down to the required size.

While making path in fab modules make note of the tool path generated. It shouldn't have any unexpected lines or moves. The move will be drawn as a line, a minor check on this before you start milling is recommended.

By default every trace is followed by 4 offsets cuts for isolation. This can be changed manually also by using the options given. If you want to remove all copper but the trace use -1 offset value, but with this approach the bit is used more and wear more per board so the number boards you can cut before the bit becomes useless is lesser.
Make path after every change. Mostly you can leave the machine parameter settings  such as depth of cut or speed etc default. These will be different for different processes. We will be mostly using 1/64(inch) bit for milling traces and 1/32 bit for cutting the board.
If the pcb is completely flat it'll result in good clean traces. If not, in some places it'll not cut or cut too deep. if some areas are not cut, then u increase the depth of cut to 0.2mm or0.15, but only wen the job is finished with 0.1 trace. Directly doing 0.2 mm trace will mean more stress on the bit and more wear and less life or breakage.
Choose a good xmin ymin position. You need to measure the board area available and the size of board to be milled and choose a good location.
Vacuum debris, after job is done. Verify the job,

Problem: We have a broken trace
The traces are very thin, and the job now is useless. The traces shouldn't go out if you rub gently on the board or not be able to easily remove it.

So we download another version of the fabisp design(Neil version of fabisp) with thicker lines and try to mill again. The links for the design are below.
http://academy.cba.mit.edu/classes/embedded_programming/hello.ISP.44.components.png
http://academy.cba.mit.edu/classes/embedded_programming/hello.ISP.44.png
http://academy.cba.mit.edu/classes/embedded_programming/hello.ISP.44.traces.png
http://academy.cba.mit.edu/classes/embedded_programming/hello.ISP.44.interior.png
Second board, dimension
22.98mm x45.2126mm

Zero position
2,55

Picking components for soldering. Go to the image where the components are mentioned.
While taking out components from the electronics drawers do not close it immediately let the box be open until you have put smd strip you have taken back into it. This is to avoid confusion when the smd is not labeled with it value or type. Capacitors can be tricky to handle because different value capacitor look almost the same. Make this a habit.
Prepare an arrangement like below. Write down material you need and pick the materials you need and arrange.
All traces look good by just lookingwith naked eye.
The traces are thicker
While removing the 1/64 exercise care
Be Holding it while removing.

Next we loaded the 1/32 bit and the outline image for milling.
Final milled stuff.
We need to pry the board out now. It would be stuck pretty firmly on double sided tape.
How it is done is you take thin ended object like the screw driver shown here.It should easily goes into the outline slot milled and move the board. Try to twist the screwdriver slowly and move the board slightly on all four corners.


Now try to pry the board out,
Pry from short side, the longer side bends doesn't bend. But below we try to pry from the longer side because the edge to the let side of the board of the base PCB broke and that gives us no fulcrum to lift the PCB up. Make sure you do not try to pry it from a sensitive area. Like an are where components or wires are passing through. This is another short coming of the white double sided tape-it holds too strong.

The board comes out with the double sided tape. The sticky double sided tape

Soldering

Stick the board with double sided that comes out and place it on a table and start soldering.
Board is stuck making it easier to handle, it wont move while soldering.
soldering order should go like more complex components to simple and middle of the board to border.
Fume extractor should be on.
Clean the soldering gun before you start the soldering operation. Opposite two diagonal corners of a component to all pins on each side one side at a time.
Difficult part is to place components, align them properly and soldering since the components are smd.

Alternate soldering technique
Put component and use lot of solder and solder all pins together, then we can use copper braid to remove excess solder. 

Problem
The USB port got sodlered in bad alignment.
We used heat gun with appropriate nozzle(nozzle with size appropriate for the size of components we try to desolder). Before using heat gun the excess solder was removed from the pads of the components.
To desolder hold the component with tweezers and lift the board and try to apply heat to the component using heat gun and apply heat flow evenly. The board should fall free of the component easily.
Don't shut off heat gun immediately, put to cool mode and to cool the heating element and avoid damage. Keep it in cool mode till normal temperature air is being output.

The final product

Preparing Laptops and Lab Computers

Since fabacademy philosophy roots in opensourcing it only makes sense that Ubuntu and the free softwares are used. This allows free and ope access to anything and everything that is done in fablab. It allows repetability and a common framework that anyone can work with. One of most important of them is the OS itself which is the linux based UBUNTU system. The next most inportant software is  the fab modules which can control alomst any CNC machine that is present in fablab.

The pain of Ubuntu 

Ubuntu means 

"A quality that included the essential human virtue; compassion and humanity. there is a need for understanding not vengance, ubuntu is not victimization"

Indeed you need to have a all these to go through Ubuntu install and setup.

Creating digital accounts

During fabcademy you will be evaluated through your documentation which explains the world and the remote mentor or Neil what you have done. There will be times when your projects will be recommended by your remote mentor to higher faculty or Neil. They will see your website or the files you created. For these reason you need to learn to effectively express your work in a document. They should be online and freely available to anyone, they are opensource.

Day 4 week 1

Lab maintenance and Material handling

I took charge of Vinyl cutter and Roland Modela

I learned how to better handle the vinyl rolls. The vinyl rolls when kept vertically deform and get damaged at the edge which happens due to it not being able to support its own load properly. The correct way to keep a vinyl material is horizontal and the rolls to be taped at the open edge after use so that they don’t become loose.

The vinyl rolls were kept on the ground earlier.

Vinyl cutting

Used to make sticker and best use is to make PCB that are flexible. Can cut copper, epoxy and vinyl sheets.

Loading the material 

Use this lever to release or secure the vinyl.

Materials should be between the two translucent patches as shown in the picture. These have rough surface in order to grip the papaer better. The wheels should secure the paper when the lever is engaged.

Day 2 w2

Laser in our fablab is a trotec speedy 100 with that we have an atmos exhaust filter from trotec. Here's the laser machine and our super cool prefab guide and fabguru Francisco explaining about the filter system.

Polycarbonate lid and Atmos Exhaust Filter system

Filter parameters

Things to watch out for

Exhaust filter should be on.

Molding Casting and Roland Modela

The basic idea for this session is to create an 3D object through computer and try to make it in machinable wax in such a way that a molding pattern is created directly from it. Roland modela will machine the wax. We will try to replicate this object by creating a silicone mold and later use the silicone mold to cast hard plastic into it.

Day 5

Shopbot

Notes:

Designing for milling

Due to tool radius inner corner of a hole or a pocket cant be sharp. Overmilling is advised in such cases.

Good design guidelines for milling.

http://blog.inventables.com/2014/06/learn-about-milling-inside-corner.html

http://www.efunda.com/processes/machining/mill_design.cfm

Better to use antimony to design material to be milled.

Dia max to be used for milling in shopbot- 6mm

Dia max to be used for milling in roland -3mm.

Week 3 Day 1

This week we move to electronics design and fabrication.

Today we started with electronics production. The goal was to fabricate a pcb from an already existing design. We use roland modela to fabricate the PCB.

Assignment: to fabricate a version of fabISP using Roland modela and fab modules.

Process

We downloaded the the following designs.

Week 3 Day2

Many of the fabacademy cad items are design that have .cad extension. These were designed in kokopelli. .cad file is basically a python script. Today we try to edit and understand how the script ad kokopelli.

Assignment

We add components to a hello.ftdi.44.cad and wires on a board and fabricate it.

Consider the following methods of programing a microcontroller

Arduino ide- most user-friendly, many tools, quick,  easy

C  - intermediate difficult, need to have more hardware knowledge, more efficient in code handling and storing, more freedom to program.

Assembly lowest level of programing, need to have through understanding of the hardware also, more difficult, highly efficient in code handling and occupies least storage, and allows most freedom to program.
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