A few years ago, we built a forge based on Larry Zoeller’s designs. We’ve used it a few times and now it’s time that the forge itself gets a bit of maintenance. This is nothing more than recoating the inside with a refractory coating to help keep the insulation in good shape. We did a quick test fire after letting it dry for a week and all was well.
Machining Brass
The cooker door wouldn’t snap closed properly. A quick disassembly of the hinges showed that a brass disc had a flat spot from years of wear and tear. Replacements were no longer available. Time to make some new ones on the lathe.
Took some measurements and started with a length of brass stock. Turned it down to the required diameter, then drilled a 4mm centre hole. Next cut a groove and parted off the new disc from the bar.
Brass is interesting to work with. It kinda crumbles off in fine particles, unlike steel. Drop in sometime and have a look at the lathe.
Project: Seven Segment Display and an Arduino Mega
Everyone has one in their house, a clock on your VCR you never set, a timer on your cooker or your microwave, a digital clock. The seven segments of LEDs that light up to form numbers are made up of Seven Segment Displays.
There are all sorts of projects you might want to add these to, but this is a basic introduction with one number.
The pins on these displays may differ, on mine, the first pin did nothing and the middle pin on the top and bottom connected to ground. Each of the other pins was a positive for a different segment on the display.
First things first, look up the data sheet of your display and figure out how much current and voltage it should take, no point burning it out. You will probably need to hook up a resister for safety.
I’m using an Arduino Mega, but you could do it with any Arduino boards or a Raspberry Pi.
Put the display in a breadboard so each pin can be powered separately and first wire up the ground with a resister, then connect it to the Arduino ground.
Then, connect a jumper line to the 3.5V on the Arduino and connect it to each pin on the Display in turn. If everything works, each segment should light up as you power it up.
To make it more interesting, wire up each segment to a digital pin on the board. For Arduino, I used pins 1-7, which is a bit interesting.
Firstly, you can’t connect pin 0 or pin 1 to anything while the sketch is uploading to the board. Once the program is uploaded, you can then connect these pins.
I used pins 1-7, and connected them to the display, skipping the ground pins.
The below code has 2 parts, and is derived from the blink program.
// the setup function runs once when you press reset or power the board
void setup() {
pinMode(7, OUTPUT);
pinMode(6, OUTPUT);
pinMode(5, OUTPUT);
pinMode(4, OUTPUT);
pinMode(3, OUTPUT);
pinMode(2, OUTPUT);
pinMode(1, OUTPUT);
// for each pin we want to use, we need to set it to output.
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(7, HIGH); // turn on whatever segment is connected to pin 7
digitalWrite(6, LOW); // turn off whatever segment is connected to pin 6
digitalWrite(5, HIGH);
digitalWrite(4, LOW);
digitalWrite(3, HIGH);
digitalWrite(2, LOW);
digitalWrite(2, HIGH);
delay(4000); // wait for a 4 seconds
digitalWrite(7, LOW); // now whichever segment is connected to pin 7 will turn off
digitalWrite(6, HIGH); // now whichever segment is connected to 6 will turn on
digitalWrite(5, LOW);
digitalWrite(4, HIGH);
digitalWrite(3, LOW);
digitalWrite(2, HIGH);
digitalWrite(1, LOW);
delay(4000); // wait for 4 seconds
}
The display is really simple, it is made up of seven LEDs and you can turn on and off each part at the same time to from numbers. This is a basic introduction, you can add more displays for more advanced features.
Lasersaur Upgrade
Last weekend we make slight few upgrades to our Lasersaur making it much easier to control air flow, extraction and power to laser just making it bit easier day to day. Thanks to all members that helped out.
Swollen Lithium Batteries
Lithium batteries are in the news for all the wrong reasons at the moment, and not for the first time.
We noticed that one of our batteries was a little swollen compared to the others. It seemed to be working OK though. We decided to open up the outer wrap to see if it was one cell or all of them, and to see if anything was obviously wrong. The battery was an 11.1V 1300mAHr LIPO. Check out some pics of us cutting off the outer black covering, to reveal that all three cells were swollen. There appeared to be no external sign of damage however. The cells feel as if they are swollen with gas.
We hooked it up to the IMAX charger to see what kind of capacity our battery had. This battery is about five years old. Its nominal capacity is 1300mAHr. We fully charged it and then discharged it. We were pleasantly surprised to find it at 1095mAHr. That was discharging it at 200mA which is about C/6. By the time the charge and discharge was complete, the pack had swelled even more.
The question now is what to do with this battery. The Internet is full of videos of people doing all sorts of crazy things to lithium batteries too. We won’t be doing any of that here. We won’t be keeping this battery indoors, thats for sure. It could still be useful for some completely remote outdoor application, away from any kind of combustible material. We should probably dispose of it safely though. Note that all of the disassembly, charging and discharging was done outdoors and with lots of PPE.
Wooden Bicycle Pump
Well not quite, but a wooden handle anyway. We don’t just do bits and bytes at TOG! The bicycle pump handle broke and it seemed a shame to dump an otherwise perfectly good pump. So with a bit of nice round wood cut from an old roller blind pole, we made a new handle. Drilled a hole in the handle and a couple of small holes in the metal shaft of the piston to give the glue a bit of grip.
We wanted to use some glue with a little bit of flexibility or “give” in it, instead of something that set rock hard. That seemed to be the way the old handle was fitted. So our old reliable hot glue gun was fired up. It sets hard, but not rock hard. Pump is back in action, good as new, and it even looks a bit rustic with its new wooden handle. We have lots of members interested in bicycle things at TOG. Drop in and see what we get up to. Pics here.