I3 Metal Gear System Extruder

I've been wondering for a while what extruder to put on my I3

I decided to try the Metal Gear System Extruder

I ordered a kit online from http://www.reprapsource.com/en/show/6770 

The web site put a scary amount of shipping cost to New Zealand, so I contacted the site owner on #reprap and he was happy to send it via normal post (3.45 EUR) , with the understanding there was no insurance or tracking. I went with this option.

This arrived!

Here are all the parts, as pictured on the site.

Plus some plastics I prepared earlier

And assembled.

It is reasonably easy to assemble but also the main shaft is a bit fiddly

Now the issues:

The mount is for a X carriage with 24mm hole spacing, the standard Prusa I3 has hole spacings of 30mm. They do provide stl files for their own X carriage, but the two lm8uu's and single lm8uu where swapped over. I didn't want to completely rebuild my X axis just to move one lm8uu.

So I made a bigger mount.  http://www.thingiverse.com/thing:84228
This is still listed as experimental, as I haven’t actually mounted it on the I3 yet.
The new hole isn't on the extruder, I used the mount as a drill guide and drilled a new hole. 

If I have assembled it correctly. I am one m3 nut short and one m3 bolt short.

I'm also left with four left over parts, which I can't find a use for.

This is probably for a different extruder mounting system

I'm fairly sure I have it assembled correctly, now I'm going to pull it apart again,
The main drive gear on the stepper only over laps the large gear by about 1 mm, I think it should have more contact, so I am going to move it a fraction.

4pi mount for I3

I've been slowly building up my own Prusa I3 Single Sheet Frame

The first challenge for me was that I wished to use my 4pi controller. This is not one of boards that there are mount holes for. In fact its to wide to mount flat on the X axis on the Aluminium directly without large overhangs.

The first step I needed the measurements from the 4pi board.  I started by just measuring the main PCB, While doing this I noticed that the various connectors are somewhat unevenly spaced, so I was going to have to measure this too. I quickly came to the conclusion that this was going to be a lot of work to measure everything.

I then had an Idea. The Eagle brd file is available, and the X and Y position data should be in the file somewhere.  I took a look at the .brd file, it seems to be well structured XML I have no experience with programming and XML, but a friend "Finch" Showed me how to process XML files in Python. The resulting components file was edited by hand to add Z axis data. The resulting Board file was modified slightly to move one component and remove a 6pin connector that isn't on he board.

The result is the following, very accurate 4pi model

This can be found here. 

So now I have a nice model to work from. I started to work on a way to mount this on my I3.  I wanted a protective box, but not enclosed so I can watch the LED's. With the model it was very easy to make a box for the 4pi and cut out all the required connecter holes.

I added a small Lip to the box so the box wouldn’t rotate when mounted on the mount arms.

The mount proved to be trickery to make that the box, mostly because I was being fancy and added rounded corners.

The mount is "RAMPS" sized, as it is attached to the ramps holes in the plate.

The final parts mounted on the machine

Files are available here
Currently its still "Experimental" as I need to tweak the sizes of the m2 nut traps.

I3's update

Partial I3 kit going on sale on trademe.co.nz soonNow (http://www.trademe.co.nz/Browse/Listing.aspx?id=579167060)

My personal I3, desperately waiting for smooth rods! (yes the Z threads is in the wrong place, it was just a convenient place to put them for the photo)

One of the issues with the internet is its to annoymous when something breaks

Case in point.  http://forums.reprap.org is currently broken with the following error.

I would like to fix it, but can find no one who even knows who looks after it..

I’m hoping this post will grab the attention of someone who can help.

 

Phorum Database Error

Sorry, a Phorum database error occurred.
Please try again later!

Error:

Table './forum/dev_messages' is marked as crashed and last (automatic?) repair failed (144): SELECT count(*) FROM dev_messages WHERE forum_id IN (236, 168, 191, 187, 186, 193, 182, 36, 57, 149, 51, 130, 173, 157, 145, 140, 93, 19, 257) AND status = -1

Backtrace:

Function phorum_database_error called at
{path to Phorum}/include/db/mysql/mysql.php:203
----
Function phorum_db_interact called at
{path to Phorum}/include/db/mysql.php:838
----
Function phorum_db_get_unapproved_list called at
{path to Phorum}/common.php:795
----
Function include_once called at
{path to Phorum}/list.php:21
----

I3 Single Sheet Frame

A limited number of these will be available soon

Still at the manufacturers for now, just arranging to get them to me.

Further details will be available when I work them out. 

Only planning to sell to New Zealand customers for now.

Taurino Power

I'm considering upgrading my Mendelmax to 24 volts threw out.

One of the issues with that is the standard mega2560 is limited to 12v, so you need to arrange 12volt power, or maybe you could power it from USB (haven’t looked into that)

I needed another RAMPS for annother project anyways so I decided to get the Taurino Power and swap some boards about. The Taurino power is a mega 2560 that is designed to run fine with power up to 35 volts, designed to be powered from a 24volt RAMPS board.

I ordered this 02/19/13 and it arrived in my hands 02/25/13, it actually arrived on 02/22/13, but needed a signature and I wasn’t around so it got delayed over a weekend.  So 3-4 days to New Zealand!

It arrived in a standard FedEx Bag

Wrapped nicely in a bubble wrap bag. I don’t know what they stuck this down with, but the glue they used refused to come off, it preferred to rip the bubble wrap than separate.

Inside that is a nice plastic box.

Inside the case, the board in more bubble wrap, and a nice looking USB cable.

I like the USB cables that you can see the sheilding threw the plastic.

The main board.

The board looks very very nice.

The board comes with a test firmware installed so shortly after turning on the tx led is on solid. It is spitting out a simple test pattern in gcode,

Unfortunately I found that I could not upload new firmware to the board.
After a bit of a think I decided to reflash the boot loader on the 2560. This fixed this issue. I can now upload fine.

I also found I couldn’t talk to this board at 250000 baud, but I suspect this is related to my machine.  The more standard baud rates work fine.

SL upload issues

I had a SL board that wouldn’t upload new firmware, so I decided to diagnose what was going on.

All I could could get was sync errors.

I had no idea as to the state of this SL so I started from the beginning. 


First some background

The SL is meant to have a boot loader on it. When the MPU is reset the boot loader is run, it is at this stage that you can upload new firmware from the arduino IDE.

The MPU reset line is tied to the DTR serial line on the FT232RL chip. Pin 2, this gives software the ability to reset the MPU using a simple serial port command.

The first thing was to check the boot loader was running.

The Standard boot loader toggles an IO line during boot up, unfortunately on the SL this is connected to E-DIR. So we cant see what is going on.

I did not want to remove my E Pololu so I went for a software fix.

I changed the port in the bootloader to one of the spare ports on the IO header. I changed it to D4.
NB this is incorrectly labeled on the SL board as D12

I compiled and uploaded the new boot loader.
I connected a resistor and led between pins  D4 and GND. NB LED's have polarity, if you need help with this see http://www.ladyada.net/learn/arduino/lesson3.html


I reset the board and it flashed as expected. So the boot loader does run. So the boot loader is fine and the fuses are probably ok.

I started up Arduino, set everything correctly, and hit upload. Nothing.
Including no flashing led!, so the software controlled reset was not happening.

I decided I didn’t want to have to load up Arduino every time I wanted to try and test the reset so I wrote (ok cut and paste bits from the internet) into a quick python script to toggle the DTR line.

***********setdtr.py*****************

import serial
from time import sleep

conn = serial.Serial('/dev/ttyUSB0',
                     baudrate=57600,
                     bytesize=serial.EIGHTBITS,
                     parity=serial.PARITY_NONE,
                     stopbits=serial.STOPBITS_ONE,
                     timeout=1,
                     xonxoff=0,
                     rtscts=0
                     )
conn.setDTR(True)
sleep(3)
conn.setDTR(False)
sleep(5)
conn.close()
**************************************

Next I checked the hardware.

The DTR line is pin 2 of the small surface mount chip on the back.
I tested it with a multimeter and under a 10x magnifying glass. Looked fine.

I checked Jumper "auto reset" had continuity, yip.
I checked Pin 9 of the MPU, Reset, had continuity to the jumper, yip.
I re-soldered cap C7, no change
I re-soldered the jumper and MPU pins, no change.

Getting frustrated, I re-soldered pin 2 on the FT232RL, Success!!!

The board now resets when I run setdtr.pl and flashes its little LED as it should.



I can only surmise that the underside of pin 2 was dry, and when I tested it with the multimeter the probe pushed the pin onto the PCB making a connection that wasn’t actually there, and I need better than 10x magnification to see this.

I then used Arduino, set it up, hit upload and after compiling the code, the board resets, the LED flashes and the code uploaded!

Success!!