Rhino, shopbot and making fabduino ready.

Rhino
We learned operation of Shopbot today and Luciano gave an introduction to the rhino 3d software. Rhino is one of the most popular 3D design softwares. It is easy to use and beginner friendly. From today's introduction I identified that it support Boolean operations on solids, workability around a Cartesian system, shells of 0 thickness, modeling interface where you have 4 views(top, bottom side and perspective) side by side which was new to me and commandline feature like in autocad etc.

I'm used to solidworks but it is easy to switch from solidworks to rhino. Most useful feature in solidworks is the parametric modeling. That means if I change the radius of the circle I used to create a cylinder with the radius of the cylinder also changes. Rhino doesn't have a history based solid creation model. That means if you use a reference from a feature and Let's say it gets deleted, solidworks would throw up an error and in rhino we are free of such a constraint, once you create a solid it is created and it is independent of the drawing or other features you used to create it from. We made a few practice drawings and solidmodels in rhino to get familiar with it. Rhino allows exploding option on a solid too. Let me explain. In autocad or any 2D cad drawing software we have an option to break a single polyline(chain of lines and curves as one entity) into its component parts which then can be manipulated individually. Rhino allows us to break a solid into component surfaces. This is a real cool feature in Rhino that can be played around with immensely. I am yet to explore usefulness of this option.

Shopbot

We changed the setting in shopbot for it to perform better. We changed the units from inches to mm first. Earlier the shopbot experienced high jerk during fast jog moves, this was resolved by setting up proper speed and ramp values.

Design rules for Shopbot
Luciano explained different designing techniques used to create stuff from
cnc routed wood among them are. Ribbing to get an overall organic look or an illusion of it. This technique cause lot of wastage. In order to improve it we could nest different parts inside a hole that is going to be cut or try to nest several sizes of ribs which will be just offset to the outermost.
Waffle technique .
Pressfit
Wood joinery
Japanese fittings
Bent wood- multiple veneers few mm thick and bendable, glued in a shape one layer at a time.

Burning bootloader into fabduino
We connect the fabisp to the fabduino and fabduino to the computer using FDTI cable and burn the bootloader from arduino after arduino has be setup to burn proper bootloader.

I added a 8MHz external resonator to the circuit now, this is optional but it is recommended to use resonator for better precision in timing. It will be helpful in generating clean PWM for the stepper motor application.
The instruction to burn bootloader  to the fabduino is given in following link. Note that some modification were done to suit our purpose hence you can follow the instruction here for the latest stuff.
http://fab.cba.mit.edu/content/projects/fabkit/

FabISP we created last week was used to burn the bootloader into the fabduino.We didn't have the jumper cable connectors necessary to connect the ISP pins from ISP to the header pins of fabduino. Hence I decided to use the 6 pin ribbon cable with end one with 6 pin female connector and the other end open to be used to temporarily connect to the header pins of fabduino by soldering it to the ends of the pins where they get soldered to the bord. I made a made a short ribbon cable with female 6 pin ISP connector, and all of its wires separated and and stripped a little at the other end. Do not strip a great length of the ribbon cable since it might cause shorting due to tangle later when soldering to header pins

The FabISP has VCC, GND, MISO, MOSI and SCK these need to connected to the corresponding pins of the Fabduino. I located the pins using the following diagram


Matching with the header connector pins we get:

VCC and GND of the bottom header is used to connect to the ISP VCC and GND
The reset pin from the ISP has to be connected to the RST pad of the fabduino. 
D13 - SCK
D12 - MOSI
D11 - MISO

For FDTI cable connection the right orientation is also given n the above image.

 The corresponding pins in FABISP are shown as J1 ISP located in the bottom right corner of the image.


I connected the 6 pin ribbon with the ISP connector on the fabisp and manually using continuity check option provided in the multimeter I matched each pin of the ribbon cable with the corresponding pin of the ISP. I proceeded to solder it to the bottom  of header pin which had already been soldered in place, for this I just reheated the solder present in the bottom of the pad which was used to solder the header pins onto the pad and poked the wires end of the wires from ribbon cable into the molten solder. This made a pretty good temporary connection I wanted.  The stripped wire strands have to be twisted properly into one strand before being soldered or else they might poke out and short other pins. After soldering all the wires i made sure no shorting is occuring among any pins.

I soldered reset wire to the RST pad, and we are ready to burn the bootloader.


Burning Bootloader from Arduino 1.6.6 IDE

Once the ISP pins are connected and FabISP plugged into your computer through FTDI cable,
go to "Tools->Board" in the Arduino IDE and pick the Arduino pro or pro mini
In the  "Tools->Processor" pick Atmega328 (8Mhz external Clock)
In "Tools->Programmer" pick "USBTinyISP"
and then pick "Tools->Burn Bootloader".

Everything went well and the fabduino now was powered up with blink program loaded and the LED blinking with 1 Sec pulse to show that.

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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