Progress with my 3D Printer

I’ve started to do more complex prints over the past few days and I was running into problems with my prints.  After a little back to basics trouble shooting I think I’m getting the hang of the machine.

My Leapfrog Creatr came with a test print in the bed when it arrived, and for the first few weeks I found myself downloading STL files from the Thingiverse and printing them no real problems. But the prints were small and quick to print.  Over the last few weeks I’ve been designing parts I would like to print and every time I tried to print a large (>80mm) part it would lift from the bed.

Here are the two things I’d recommend you do:
1) PLA only requires a bed temperature of 60 degrees C, lower it from the default 90.
2) Level the bed as soon as you get your machine! (It was level when it left, but is it when you crack the shipping box!?)

After doing these, I’m starting to get really great results! Now I’m able to do bigger and longer prints without worrying too much if they are going to go wrong.

The first of these was a box for my Carambola i2c IO board (which has been converted to a Raspberry Pi controller, but that is another post!).

Here are the results:

RPi Heating Controller - Top section with Raspberry Pi mounting holes

RPi Heating Controller – Top section with Raspberry Pi mounting holes

Top of the box with the Raspberry Pi fitted:

RPi Heating Controller - Top section with the Raspberry Pi mounted

RPi Heating Controller – Top section with the Raspberry Pi mounted

The top and bottom:

The RPi Heating Controller - Two halfs with PCBs installed.

The RPi Heating Controller – Two halfs with PCBs installed.

The box assembled:

RPi Heating Controller - Assembled - top view front

RPi Heating Controller – Assembled – top view front

The side with access for power and Ethernet:

RPi Heating Controller - Assembled - view of the power and comms

RPi Heating Controller – Assembled – view of the power and comms

The output connector side:

RPi Heating Controller - Assembled - View of the output connectors

RPi Heating Controller – Assembled – View of the output connectors

All good.. at last I can call this one done!

Mis-adventures in OpenWRT (TL-WR741ND)

While waiting for a long 3D print job to finish, I got to installing OpenWRT on a TP-Link router I have here in the office… The long and short of it, I managed to brick the device. Even thought the TL-WR741ND is supported by OpenWRT, I managed to flash the wrong image on to it.

So what to do next.. It was cheap and I was going to scrap it and forget about it, but I couldn’t let it go!  I popped to cover and read about console access over on the OpenWRT site.

I dug out one of my USB FTDI cables and got soldering…

TP Link TL-WR741ND with cover off

TP Link TL-WR741ND with cover off

Simple enough to connect to a serial lines back to the FTDI break out board. TP4 is TX, TP5 is RX and ground is taken from the bare copper trace.

Tap points for UART

Tap points for UART

Got a serial terminal program up and running on my lab PC, set to 11520,n,8,1.  Turn on the power and bingo, console data coming thick and fast! Cool.. except the Linux image I had flashed didn’t want to boot.  Corrupt image file, the boot loader was stuck in a loop.

How to stop uBoot from cycling all the time and get access to the CLI?
Tried the ESC key a few time, no joy.. Reading around the web someone else suggested the ~ key.. still no luck.  I found a post about another TP-Link router and mention of the keystroke “tpl” to get to the uBoot CLI.  Typing really fast then the “Autobooting in 1 seconds” message came on the console, bingo the boot loop stopped and I had a CLI.

Serial uBoot debugNext, how to get a new image flashed? Well that is quite easy with uBoot.. One can flash an image from a TFTP server. So armed with the correct image and a running TFTP server, this is what I did on the console:

ar7240> setenv serverip <TFTP server IP>
ar7240> setenv ipaddr <Temp IP address on my network>
ar7240> tftpboot 0x80000000 orig.bin
ar7240> erase 0x9f020000 +0x3c0000
ar7240> cp.b 0x80000000 0x9f020000 0x3c0000
ar7240> bootm 0x9f020000

Reboot, and we’re good…

Carambola i2c IO board with relays – V1.1

I’ve been working on a new version of my Carambola IO board.  I’ve added an interrupt line from the MCP23017 back to the Carambola to allow for a trigger when an input changes (save on having to poll the MCP23017 to check for changes!).

One other small change was the addition of a decouple cap close to the pin headers for the Carambola module.  It helps to keep the +5V in order, on the first version there was a lot on noise on the 5V line. You can get the new schematic here: Carambola IO Board

I re-generated the artwork, broke out the light box and development kit and got to work “spinning” a new PCB.  I’m happy with my timings for exposure and development now and seem to have a repeatable process in place.

Carambola IO board - main components placed

Carambola IO board – main components placed

The double sided PCB above took about 2 hours from PC screen to etched PCB (not drilled!). Got a good clean PCB with well defined tracks.

Carambola IO board - close up of I2C extender

Carambola IO board – close up of I2C extender

Getting the new Carambola module configured was easy.  Once connected to the network I could simple copy my Lua MQTT code from my original board over SSH.

Carambola IO board - ready for testing

Carambola IO board – ready for testing

Now I have to write some more Lua code to handle the interrupt pin and post the changes on the inputs via MQTT!

The EthNode – ATMega based Ethernet board

Taking inspiration from the good folks at Nanode and an Instructable I saw recently, I’ve come up with “another” AVR based Ethernet board that can be programmed and used like an Arduino.

It’s a simple design based on the ATMega and Microchip’s ENC28J60 Ethernet controller with SPI.  Running MQTT on one of these will open up a few options for home automation and remote sensor monitoring.

It’s not as complex as the Nanode.  It doesn’t have the Arduino header locations, but all the major pins are available at headers. There is a 25L512 chip providing 512 Kbit Serial EEPROM for MAC addresses and logged data if one needs it. The PCB is only 80x50mm in size!

Here is the schematic:

EthNode Schematic

EthNode Schematic

Here is the PCB layout:

EthNode PCB Layout

EthNode PCB Layout

All the resources (KiCAD files, libraries, etc) can be downloaded here:Ethnode-V0.9.tar

This morning I got a delivery from Farnell with all the parts.. Busy weekend ahead!