Makerfarm Prusa i3 Fan Mount

One recommendation to me was when printing PLA add a cooling fan to the black section of my hot end. I've had a only a few instances now where my extruder had spotty performance. One instance there was a bulge in my filament that could not go through the diameter. This required an additional disassembly of my extruder. It is my understanding the heat can conduct up the filament and get soft near the hob bolt. To avoid this I purchased a small 40x40 mm fan to provide cooling over the PEEK material of my J-head. Makerfarm recently came out with a new extruder but I have the "older" model so I had no holes in my extruder to mount my fan. I decided to make a fan mount that is retained by the two X-axis bolt holes used for the X-axis stop.

Front View with 2 holes for the fan

Back view where there is an angled section to match the wood
cutout of the X-assembly

I measured up the dimensions of the X-assembly and modeled it. I added 2 bolt holes on the side for the screws that attached it to the X axis assembly and matched the angled section of the X-assembly to prevent it from rotating about the bolts. There was one weal spot in my print where my extruder crapped out for a few layers.

Fan attached to mount

My motor has a 3rd wire which is used on a motherboard as a tachometer. In this case I will not use it but thought it be fun to have if I ever wanted to do anything with it. My motor is 12 V so I can hook it right up to my RAMPS board on the 5A power terminal. It will run all the time but I think I'll put a small switch in the line and mount it to my printer so I can turn the fan off and on. 

Fan mount attached to the X assembly

 I am really pleased with how it turned out. The weak section of my print actually broke on one side but still is really stable. I may print another one later. The fan does not blow over the hot end, only over the black section of my extruder. It is a very small amount of flow and should help. You can download the .STL file for the Fan Mount. 

Back with a 3D Printer

It has been over a month now since I wrote my last blurb. Life has been rather busy but I ended getting the Prusa i3 8" Printer from Makerfarm.

It comes as a kit but it was a lot of fun to build. Only additional items you will need are a piece of glass to print on and an ATX computer power supply to run 12V to power the board and printer. I assembled mine and did a few of the initial test prints to see how well I did assembling. I am completely new to this so I was not familiar with print temperatures and calibrating so my first prints were very crude. I contact Colin at Makerfarm for some pointers and he was very helpful and quick to respond. I checked the calibration and did some maintenance on my machine. It ended up I had to completely disassemble my extruder but this was rather painless. When I originally built it, I had a tough time putting the components together. In my case the plastic idler did not contact the filament and I did not have enough preload on my springs to extrude the plastic so I ended up with a few good layers of print, then a few bad and back to a few good.You can see in my print how spotty it was and offset.

My new prints are much improved now that I trimmed some material off my extruder and the fits are much better. I am working on my first large scale object but I printed a small piece last night that turned out very well. It has nice edges and a great radius on the one section.

I am still learning how to more effectively use Sli3er which creates the Gcode for the printer. Overall I love my printer and I think it was a great buy for the price. It took some work getting it honed in but you get to become more familiar with the machine itself. Highly recommend this printer to anyone else. I'll continue to post projects that I am working on and parts that I create. I'll manage a way for everyone to access my .STL files as well.

I've Been M.I.A

I have not posted in awhile but I have not forgot about da Yetti Cave. I will have new posts soon and I will be getting a 3D printer (finally)!!!!! This will be huge for me because I don't have room for a legitimate workshop. However, I did come across this awesome MakerSpace in San Diego which I may have to pay a visit to. Links below:

Makerplace San Diego

BeagleBone 1.8V Analog Logic

Intro

Unlike the Arduino which uses 5 V logic, the analog pins on the BeagleBone Black require a 1.8 V signal for the Analog to Digital converter (The device itself is 3.3V. I always have concerns doing something new with my devices with the fear of destroying them. Not being an expert in electronics, I tend to ask a lot of questions and before I make a move. The two things I wanted to get answered in the case of using the analog pins on the BBB were

1. What if a sensor does not have a datasheet or specified output voltage; is it or would it be less than 1.8 V for the BeagleBone?

2. If it is over 1.8 V, how do I use the sensor?

I'll answer both these.

Finding a sensors output voltage

This  I think was the most intimidating part of using the analog pins on the BeagleBone. I have data sheets for most my sensors but out of curiosity I did not know the best way to figure out what the output voltage would be for the maximum in put voltage. I posted the question on Google + and got a response from Jason Kridner, who is the BeagleBone aficionado from TI. He suggested I purchase the DSN Nano Oscilloscope from SeedStudio.

What advantage will this give? Almost all devices specify an input voltage on the data sheet. Using an oscilloscope will allow you to vary an input voltage to a sensor and measure the output voltage of the device. (You could do the same with a multimeter but I wanted to add an oscilloscope to my toolbox). 

Using Analog on the BeagleBone

Hipstercircuits had a great write up on how to enable the driver for the analog pins. Follow this link. The BeagleBone Black has specific pins that are analog. They are physical pins 33,35,36,37,38,39,40 and 41 is analog ground. I used my TMP-36 temperature sensor for my first analog project because it outputs 1.8 V. This is the maximum allowable for the Analog to Digital converter on the BBB. Here is a shot of how it was hooked up. Red is 3.3V, Black is ground and Blue goes to one of the analog pins. A cheat sheet can be found below for the physical pins and I labeled the analog pins.

The BeagleBone will give the measured values in mV so the values you will read from the low hundreds to about 1800. To acccess a specific pin you can execute the following command:

TMP-36 Sensor Wiring

cat /sys/devices/ocp.2/helper.14/AIN1

This will access AIN1 which is physical pin 40. Just as I did in my Blink.py example I wrote a python script to read the analog value and convert it to a temperature based on the information Adafruit provides for with the data sheet for the sensor.

The python code can be found at this link TMP-36.py

On my particular device the path is "helper.14" but I have seen others with a different # on their directory. If 14 does not work for you just type "helper." then tab and it will fill in auto complete.

I'll answer the question of "If it is over 1.8 V, how do I use the sensor?" in my next post.

Up and Coming!

Sorry its been awhile since the last post. I am working on discussing analog inputs for the BeagleBone Black and the analog 1.8 V logic. I'll post on it this week with an example. Also I'm working on a homemade Breathalyzer I'll be sharing. Some other projects are postponed because I need a 3D printer!!! Then I dont have to relie on others for special parts. Scanner is on hold for that reason but I did get some wood to build the base and can start mounting.