While Arduino and Raspberry Pi dominate, there are other boards out there for robot builders.
One of the best for rapid robot development is IoTiny from EZ-Robot. [Read more…]
DJI/Ryze Tello Mini-Drone Review
DJI/Ryze Tello Mini-Drone is, as the name suggests, a new and tiny drone from the people who created my lovely DJI Mavic Pro. The important differences are, however, compelling: [Read more…]
Running Raspberry Pi AND Arduino for the Best of Both Worlds
I have been writing a lot more about Raspberry Pi than Arduino lately, but don’t get the impression I am leaving the Arduino world behind. Both devices have their benefits, and in fact, I believe they work really well together.
Let’s take a look at the easiest way to do that! [Read more…]
Linux Automation Tips: Create a Boot/Start Menu with Python
You may have seen in the Maker Hacks Facebook Group the latest iteration of my Raspberry Pi based entertainment center. It’s now got to the point where I need a boot menu, so I thought I would share the code and implementation with you!
Code
See the full code in the Gist.
First we need to add the readchar module. Use pip3 install readchar.
This module simplifies interpreting keypresses, otherwise, we would need to look up the escape codes and such ourselves. Not fun.
The other module is the os module which allows us to clear the screen (os.system('clear')) and launch programs.
Once you have done this it is a simple case to do an infinite while loop and look for the specific keys we want the user to choose from.
Remember I said the module helps us? Check out where looking for the Enter key is made much easier:
if(key == readchar.key.ENTER):
We launch the programs using os.system – you can get more clever with it but this works for our purposes.
import os
import readchar
# place in your start up file:
# sudo nano ./.bashrc
def menu():
while True:
os.system('clear')
print("\t\tChoose from the following options:\n\n")
print("\t\tk: Kodi")
print("\t\tr: Retro Pi")
print("\t\tx: XWindows")
print("\n\t\tEnter to quit to terminal\n\n\n")
# Read a key
key = readchar.readkey()
if(key == 'k'):
print("Launch Kodi")
os.system("kodi")
elif(key == 'r'):
print("Launch RetroPie")
os.system("emulationstation")
elif(key == 'x'):
print("Launch X Windows")
os.system("startx")
elif(key == readchar.key.ENTER):
print("Exit to terminal")
break
else:
print("Please choose an option from above")
if __name__ == "__main__":
menu()
Using Grove Sensors, Buttons, and Displays, with Raspberry Pi and Python
Grove sensors are a plug and play way to add sensors, buttons, displays, and actuators to your electronics projects, without soldering. Let’s take a look how well they work when paired with a Raspberry Pi!
Linux Automation Tips: Running Scripts Automatically
Running commands from the shell is all well and good, but what if you don’t want to always be logging into your terminal? What if the script, or even server, crashes or needs to reboot? In this series, we have been looking at automation in Linux, and nothing is more important than automating the launching (and relaunching) of your scripts. [Read more…]
Password-Less SSH Access to Your Linux Machine or Raspberry Pi Using Public Keys
If you are logging in and out of a Linux machine, especially a Raspberry Pi on your local network, it can be a pain to keep entering a password. The longer and more secure your password, the more of a pain it can be. If only there was a secure but convenient alternative …
Well, there is! [Read more…]
Finally, Prusa Mk42 Heatbed for the Prusa Mk2/Mk2.5, and Pinda Sensor Clones!
The Prusa Mk2/Mk3 3d printers are renowned as top quality, but buying parts is a painfully expensive deal due to the long journey and single supplier. That just changed! [Read more…]
Linux Automation Tip: Kill Script if Already Running
Here is a shell script that will allow you to kill a script if it is already running
#!/usr/bin/env bash
ps -ef | grep $1 | awk '{print $2}' | xargs kill -9
Supply the name of the script as the first parameter and it will look to see if there is a matching process, and if so, kill it.
Obviously this is something you need to be careful with!
Code Breakdown
- ps -ef – this gets our list of running processes, along with the command that is running and the associated process IDs. We need to match the process against our supplied keyword ($1) and get the ID back.
- Grep looks the text output by the PS for the keyword supplied on the command-line ($1).
- Awk takes the columns of text from the Grep search and extracts the second column, which is our process IDs.
- Xargs allows us to iterate over a list (of IDs in this case) and run a command against each entry. This is where the killing happens.
- Kill -9 means “nuke from orbit” 🙂
I am assuming if you want to do this you really want to do this. If it is not such a priority then don’t use -9 and give the process a chance to end gracefully.
T8 CNC Kit Review
The T8 CNC is a desktop CNC kit built with aluminum extrusions, open source Arduino hardware, and GRBL software. If you were looking to learn CNC, perhaps this little $200 CNC mill could be a good start?
T8 CNC specs
Firstly, we need to address the obvious. This CNC mill is tiny. The cutting area is roughly the size of an A6 piece of paper. 130mm x 10mm x 4mm.
It does, however, come with a decent 24v motor as the router, getting up 7000rpm (not necessarily PWM, as we will discuss later).
This is why a lot of stores and reviews described it as for PCB milling. It is small but beefy.
There are a lot of these machines out there and they all seem to have variations. Mine came with no instructions or software but did come with 4 v-cut end mill bits.
The T8 runs using an Arduino Uno clone and a CNC shield. Pretty standard stuff.
What can the T8 CNC do? What is it good for?
If it is so small and has a motor rather than a commercial router, what is it useful for?
First I would say due to it being a kit, the fact it is based on open hardware and software, and because it is so small, it would be good for learning, especially in a small classroom or makerspace. Everything learned on this machine is applicable to larger CNC operations.
We already mentioned that people see this as a PCB mill, but it can also handily cut and engrave plastics and wood, maybe even soft metals, though I did not try.
Building the T8 CNC Kit
As mentioned earlier, as for instructions you are pretty much on your own.
I did the crazy thing of just working off product images, and it worked out mostly. On the Gearbest product page, there are some videos and links, plus there is an Instructable here that seems to be a slightly different machine to mine.
There is some soldering, the steppers arrive with snipped wires rather than connectors. My crimping tool came in handy.
You can get it working relatively well enough after building but set a good weekend aside, don’t expect to build and run this guy over a lunch break.
Other than documentation – Any problems?
Unfortunately, the CNC shield is not set up for the pins of the latest GRBL firmware. After a little hacking and snooping I found I could connect the motor signal pin to the Uno and get it working.
While in theory, the machine is capable of speed control, the kit as arrived uses a relay to turn the motor off and on, so that’s all you get as far as control is concerned without mods.
Modifications and Upgrades
Gearbest sent me this machine knowing I was into CNC (see future articles about my Sienci and X-Carve). While I was tempted to try some PCB milling, and still might, what I am more intruiged about is the upgradability of this guy.
It is built with standard extrusions, lead screws and smooth rods … so I bought some new larger replacements. When the weather is better I will be taking all this to the Fuse33 maker space and upgrading. Look out for an update.
Bottom Line
If you are prepared to do a bit of research and effort, this is a fine little machine, and not only that, a good foundation for a much better machine. Think of it as buying a bill of materials for a CNC, rather than something that will give you support and hand holding.
