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Making a Redsail Laser Cutter Fence .. on the Redsail Laser Cutter

If you’re using the Redsail Laser Cutter at the Vancouver Hack Space safely then the worst that can happen is your cuts don’t cut. The laser goes around, you smell the burning, and when you touch the pieces to lift them from the bed the whole sheet moves because – whoops – the beam didn’t go all the way through. Now that you’ve moved the sheet, you’ll just have to scrap that cut and try again.

So the next time you lean into the machine you put one hand down to hold the sheet and with the other you nudge the piece. Yay, one of the cuts worked! …kinda. The interior holes didn’t cut completely and there’s a few funny spots that .. aw, heck, you moved the hand that shouldn’t move.

Clearly, there’s a need for a better way. Something that will make it easy to hold the sheet at the same place for each cut to waste less material. It can’t stick up above the material or the laser head might hit it. It has to be made of material that the laser can safely cut, just in case. Something easy to make again would be ideal. Something that doesn’t damage the machine when it’s installed (no bolting or gluing or welding).

I noticed a gap at the front of the machine, just inside the door. Using a few scrap pieces of material I cut a simple two piece system. slot them together in the gap, push it to the far left, and you now have a right angle fence to line up your cuts.

If you need to make another, look in Desktop > Laser User Files > Dan R > Fence.

It’s not perfect. Can you improve on the design? Let me know by commenting below or in our forums.

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Rotary Stewart Platform Code on Github

Here is the Rotary Stewart Platform Code on Github. I have a lot more code from the old project that needs to be updated to work with this model. If you’re patient, stay tuned. If you aren’t, join in and start writing code.

And since everybody loves pictures, here’s an unrelated image of my first PCB, an array of QRD1114s for the maze-solving HOG Drive robot. Yes, it’s missing two 220 ohm resistors. Fixing that tonight at the Vancouver Hackspace.

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Miniature Rotary Stewart Platform Demo

I made a Stewart platform like this several years ago and used aluminum parts that cost a small fortune. I had it stuck in my head that no one would ever want one because it was too expensive. Recently I was contacted through my website by someone who found my old machine at Let’s Make Robots and wanted to buy one. It’s like a light going off in my head when I realize “Hey, this is actually affordable now!”

Long story short: I’m going to work on the printed parts a bit more over the next two weeks and then get this into the store for anyone interested. The code will go up on GitHub. Can we get it to work with GCODE like most of the other machines? I think so.

Stewart platforms are used in flight simulators, driving simulators, robotic surgery, and even docking shuttles to the international space station.

Here’s an idea: Stewart platform + GPS + clock + telescope = DIY star tracking. Just putting that out there.

The most challenging part of assembling this kit is cutting the rods in half. Just FYI.

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HOG Drive Line Following with QRD1114 Sensors

You can find more great stuff like this @ www.marginallyclever.com.

I’m using QRD1114 Infrared sensors to control the movement of a Hemispherical Omnidirectional Gimballed (HOG) Drive for a line riding robot.

I’ll probably mount five of them in a row so I can expand the code and make a maze-solving robot. This thing is fast enough that I’m also going to need a PID controller in the software.

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QRD1114 Circuit How-to Tutorial (or “Where did I put my brain?”)

My line following/maze-solving robot has been bust for too damn long. I just spent two weeks staring at this circuit, unable to figure out why it doesn’t work. Can you see it?

Neither could I, at first. I thought maybe the QRD1114s had been assembled backwards, but that couldn’t be right, could it? It wasn’t until I took a break and restarted from square 1 that I spotted the error, which – I’m sorry – is not in this photo. I the + and – lines connected to the breadboard were reversed, I was running power the wrong way through the circuit. When I looked at the board I saw what you see in that picture. The wires were right there in my peripheral and I missed them completely.

There’s a lesson in every mistake. What is the lesson here? Double check everything? I thought I had. Reconfirm your assumptions? That’s improbable going on impossible. I wonder how many times I will have to wire things backwards before I learn to check it every time. How many times do you have to experience a lesson before you learn and pass the class?

Below is how to wire the correct circuit. I’m using 1k resistors for the sensor and 220Ohm resistors for the IR LEDs. The dot on the top of the sensor is next to pin 1. pin 1 and pin 3 are 0.050″ longer so you know they’re the positive legs.

Here’s a single sensor in the array, isolated for simplicity.

Here’s the sample code I ran on the Arduino.

[code lang=”c”]void setup() {
Serial.begin(57600);
Serial.println(F("Hello, World!"));
}

void loop() {
Serial.print(F("0=")); Serial.print(analogRead(0)); Serial.print(‘\t’);
Serial.print(F("2=")); Serial.print(analogRead(2)); Serial.print(‘\t’);
Serial.print(F("4=")); Serial.print(analogRead(4)); Serial.print(‘\n’);
delay(100);
}[/code]

Here it is working in a robot.