Safety Gear
Ingredients
Method
Mix water and gum powder. Avoid clumps by stirring vigorously while sprinkling the powder. Add other ingredients and mix until a consistent liquid (as in no sticky stuff at bottom and fluid at top).
Some gum will still be clumpy. Leave until dissolved and then mix again to ensure consistency.
Needed something to protect the metal frames of the kiln I’m building from rust.
High Temperature paint is pretty easy to get a hold of. Found roughly 3 ranges: 300 °C, 500°C and 1000°C. The 1000°C range needs to be baked in an oven at 200°C to go hard.
| Name | Temperature Range | Supplier | |
| VHT Very High Temperature | 704-1093 | AutoBarn,Repco | |
| VHT High Temperature | 343 | AutoBarn,Repco | |
| Dupli-Color High Heat | 1093 | SuperCheap, Repco, Caswell, Autobarn | |
| Whight Knight Hi Temp | 540 | Bunnings | |
| Dulux Dura Max High Heat | 300-690 | Bunnings | |
| Rustoleum High Heat | 650 | Ebay | |
| Hammerite High Heat | 600 | Tenaru | |
| Armor High Heat | 650 | Automegastore |
While writing the software for my wife’s new kiln I encountered a blocker. The MAX31855 module I got off Ebay wasn’t cooperating.
The SPI coms worked fine but the values received as cold (internal) temperature and probe temperature looked like they were random. Ordered 2 and they were both duds. Thought it might be a 5v vs 3.3v issue on the data lines so used a resistor divider network on he Scl and Sd lines on the second module just in case I damaged the first. The culprit unit:
Then ordered another 2 from a different supplier. This time the chip kept on replying with a short to ground. After some investigation the probe negative line was shorted to ground by an intentional track to ground on the PCB. Cut that track to break the connection and voila, error gone.
Last challenge was to get a stable reading. Turns out a 10nF ceramic cap across the thermocouple at the connection to the PCB was good enough. The values were alternating from 15 to 32 degrees before the modification. After the change it was a stable 24 degrees.
Lessons learned:
| Category | Channel | Comment |
| Welding | ChuckE2009 | Knows his stuff. Good info on various types of rods and videos of welding puddle showing techniques. |
| Metal Machine Shop | ThatLazyMachinist | Knows his stuff (and he should as an ex-teacher). Machine shop lessons and various metal working projects. |
| Metal Machine Shop | Mrpete222/Tubal Cain | Editor of some of the ever popular Workshop Practice Series books. |
| Metal Machine Shop | This Old Tony | Unique presentation skills of various tips and projects. |
| Metal Gadget Prototyping | Dan Gelbart | Some really good techniques on achieving precision and prototyping. |
| Woodworking | Matthias Wandel | King of wood gears. Makes machines and stuff out of wood. |
Having a list of what is in the workshop makes designing a breeze. The more information you have available to you while you are in front of the PC the less time you spend running between the workshop and your desk. Knowing what you have available to work with makes a lot of decisions easy. So I have compiled a list of what materials and tools I have available.
Yes its a pain to keep it up to date so I try to update it whenever I buy stuff and as I use/break things I just update a whiteboard in the workshop or jolt down a note on my phone.
Lets face it, all projects require some form of material or consumable. I’ve compiled a list of suppliers I typically use for various items. These items range from chemicals to pieces of stock metal.
Why do I choose the suppliers I buy from? When designing a project one not only has to be creative in solving a problem but finding cost effective materials for the solution sometimes makes/breaks the viability of a solution. If you can’t cost the solution given a certain set of materials, you can’t evaluate the viability and ability of fellow hobbyists to obtain the material. If nobody can get a hold of that special grade Alu or electronic component I used, I am the only person that will build the project. That does seem like a bit of a waste of valuable time and effort to document the plans for other people.
Without further ado, the list:
| Hare & Forbes | Brisbane | Metalwork Tools | About the same price as imports after shipping. No waiting 4 weeks for tools. |
| Ausee | Lathe Tools | Aus supplier of Sieg brand machines and accessories. Shipment faster than overseas but tad bit more expensive. | |
| Early Bird Steel | Brisbane | Metal Stock | AS300 mild steel with some odd bits of Alu and harder steel. Friendly faces (mostly) with Luke and Don being rather helpful. They are a bit far out from my place but the online pricelist is worth it when designing and deciding what stock is a better fit for the project. Open on Saturday mornings is a major boon. |
| Action Aluminium | Brisbane | Metal Stock | Extensive range of Alu and open on a Saturday morning. Pity about the pricelist not being up on the site. |
| Scott Metals | Brisbane | Metal Stock | AS300 only. Closest to my place but more pricier than Early Bird. Why buy from them? Online pricelist and open on a Saturday. Friendly face here and there but only once you’ve had a chat or two. |
| Bolts & Industrial | Brisbane | Nuts & Bolts | They sell other tools and chemicals but a bit pricy for the hobbyist. The price of the nuts and bolts are comparable to imports but obviously available a lot quicker. Over the counter is a no-no for varied orders, rather phone it in and collect when ready. Online pricelist is available. |
| Umart | Brisbane | Computer Hardware | Where I tend to get my PC spares. Nice and close to home and reasonably priced with lots of stock (range and quantity). |
| Pottery Supplies Online | Brisbane | Forging | Nice and close to home but a tad bit pricy. Online pricelist available. |
If anyone has a regular supplier in Brisbane that they use for electronic components, materials and tools, do feel free to add it in the comments. If they see my business I will add them to my list.
Learned the hard way why my power supply circuits weren’t working.
Here’s the circuit:
Pretty straight forward, 12V in 3.3V out. Built a couple of these before and they all worked without hassle. Not this one!
Switches on, works for 1-2 seconds and then the voltage drops over the input terminal and the LDO (LM1117) starts heating up. The same happened on a regulator (78L05ACP).
What’s wrong you might ask? After fiddling a bit with the capacitors, I found that they would start heating up when you swap them in and out of the circuit. Turns out I had the polarity wrong. Haven’t used SMD components a lot and on SMD caps the solid line usually indicates the positive terminal, unlike through-hole caps where the line is on the negative terminal’s side.
These were tantalum; guess if it was electrolytic stuff would have gone pop. Interesting symptoms though, a reverse polarity tantalum starts off okay and then avalanches into a dead short. This in turn heats up the capacitor and if it is the capacitor at the output terminal of the LDO, the LDO also starts to heat up pretty quickly. Doesn’t look like there was any permanent damage done. The LDO has built in short-circuit protection and the caps didn’t show any signs of wear and still tested 10uF after multiple rounds of heating up.
All sorted now. Power supply up and running. Now back to the original project: Temperature regulated polystyrene cutter.