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P-102: Remote Drone: Project Update

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I have decided to complete this project after a long hiatus. I had completed the frame of the robot and the video transmitter and receiver, and I was working on attaching the wheels.
I have ordered some 12mm pillow blocks to fit the axles of the rear wheels into, these will not be powered, just free rotating.
I am also researching motors for the front wheels. This is proving to be more difficult that I thought. I believe the motors I had chosen previously while working on the project weren’t powerful enough. It is possible that I confused the “stall torque” with the ” rated torque”. The stall torque is the max torque that the motor can produce under any circumstances, however, the motor should not be required to produce more torque than it’s “rated torque” over a prolonged period of time.
My robot needs a rated torque (per motor) of about 24.01 kg-cm. This is very high, most motors seems to be designed for much smaller robots, while mine is a larger off-road type of robot, with a heavy chassis. I would estimate that, fully loaded, my robot could weigh up to 5 kilos.
I have found one motor that I think will work, HERE. The only thing I am worried about is it’s low (45) RPM. This would make my robot very slow, unless I use a gearbox, which would reduce the torque in exchange for speed.

I could use four motors instead of two, but this would make it more difficult to program and control the robot. There are other motors that are powerful enough, but they have RPMS that are too low, as well as shaft diameters that won’t fit my current shaft couplers (which are 6mm).

I am thinking of using some very simple short range wireless radios to control the robot. I have used them before, they have a range of a few hundred meters and are easy to use with the Arduino microcontroller. I had intended to use either long range radios with directional antennas, or a GSM card, which would allow me to control the robot from anywhere where there is a mobile phone signal, but I want to get proof of concept first, using technology that I have already.

I think I can probably finish the robot fairly easily, especially if I use mostly hardware that I have already. I would just need to buy some motors and mountings and a motor driver capable of handling the high amperage of these motors (the stall current is 20A per motor!) .

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P-160: Metalworking Forge Update 6

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This time I concentrated on the hilt of the blade. I began rounding out the handle, and making the finger choil (the protrusion at the end of the hilt, just before the blade, designed to prevent the users fingers slipping onto the blade during use).  I also flattened out the blade more.

The top of the blade is bent slightly, this will need to be corrected. This happened while I was making the indentation for the finger choil.

The next goals are to finish flattening the blade, finish rounding the handle, and then finish the finger choil. After than I just need to temper it and polish it, and the basic blade blank will be done.

 

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P-160: Metalworking Forge Update 6

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Included are some pictures of my third forging session with my Damascus steel knife.

It is finally starting to look like a knife. The tip of the blade is mostly done, and I have started narrowing the length of the blade in preparation for filing.

I have to narrow the blade further, add the indentations for the hilt, and round the rear of the hilt. Then I will need to temper, polish, and etch it, before creating the hilt itself.

 

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P-160: Metalworking Forge Update 5

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I have uploaded some pictures of my second forging session. My knife is already starting to look vaguely knife-shaped, with the tip coming together nicely.

I now need to work on the handle, refine the tip, and flatten the blade in preparation for taking an edge.

I think the tip of the blade was the hardest part because I had to work the steel at a very awkward angle, and it kept slipping under the force of the hammer.

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Remote Connectivity Solution

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I have recently been thinking about purchasing a device that I can use to remain connected while in remote areas.

There are many options available today to solve this particular problem, from smart phones to tablets, and from 3G dongles to wifi antennas. However, I was surprised at how difficult it is to make such a system truly portable for long periods of time, while still remaining connected to the internet.

Firstly, I could not find a single phone, tablet, or laptop with a built-in jack for an external antenna. When using a device in a remote area, this is essential. The only option would be to replace the built in 3G/4G or Wifi card with a dongle, and then connect an external antenna to the dongle. This is inefficient and adds needless bulk to a system designed for portability. It can also difficult to find even dongles with antenna jacks, many don’t have them.

The second issue is power. There are several types of solar panels and external batteries available for mobile devices, however, for a larger tablet, or small netbook, it is difficult to know if these would be sufficient. A small tablet may not be powerful enough to perform adequately over a longer period of time, especially for an individual who demands a lot from their computer.

Another problem that needs to be solved for a device like this is which operating system to get. Most small tablets use Android or iOS, and these mobile operating systems work fine for general tasks, but for individuals who require more from their device, or who want to integrate more easily with other computers, programs, or file formats, a desktop operating system (Such as Windows 8.1) may be required. However it is rare to find a Windows 8.1 device under the 10″ screen size mark, which makes them big and power-hungry.

The ideal system solution, for my purposes at least, would have:

Screen size between 7.x” and 9.x”. This should be big enough to be usable, while still being small and power-efficient.
Feature a desktop-operating system. (Windows 8.1 is usually the only option, but I have seen some flavours of linux installed in these machines too).
Feature extensive power-saving features and long battery life
Have support for an external 3G antenna. (This is likely not possible without an external dongle)

I am currently researching various options in this area, and am torn mainly between getting a small tablet, and learning to conform to Android as my primary operating system, and buying the smallest Windows 8 tablet that I can find, and hoping it’s not too big or power hungry.

P-160: Metalworking Forge Update 4

P-160: Metalworking Forge Update 4

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I have included a video of my first forging attempt that I just had converted.

Also, I believe I have solved most of the problem with the forge.

I have discovered that it is possible to weld using just car batteries. I could use some very simple tack welds to create a handle to hold the work piece.

Adjusting the position of the fan should sort out the issues with airflow, and I have made changes to my improvises anvil (although I probably still need to get a real one).

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P-160: Metalworking Forge Update 3

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I have completed a test firing of my forge.

It seems to work well, I can easily bring the Damascus steel up to forging temperature. I have noticed some problems however.

First, my anvil is insufficient for the kind of work I am doing, secondly, the air flow is not strong enough, and thirdly, my method for holding the work piece is too weak.

I can fix all of these issues fairly easily, and even despite them, I was able to work with the steel relatively easily.

I have noticed that, even with a small bar of steel like the one I started with, it does stretch quite a bit when worked. As I made the end of the steel narrower for the point of the knife, the sides protruded quite a lot.

I was originally trying to make a small knife for the purposes of bushcraft, and general use, however, it looks like the blade will end up being longer than I planned to make it. I could cut some of the excess steel off, if I need to.

 

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P-160: Metalworking Forge Update 2

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I have mostly completed my forge design. I am using regular (non-fire bricks) to make the outside of the forge, and I am lining the inside with fire bricks. I am then using fire cement to seal the cracks and joints between the fire bricks.

The air pipe is a 2 inch diameter exhaust pipe tube, 1 meter long. I have drilled 10 small holes in it, and sealed the end with a thick layer of fire cement. The holes are placed in such a way that the length of Damascus steel that I will be working with fits over them exactly, without wasting airflow.

I am introducing air into the forge by using a 12V fan. I am somewhat concerned that this will not be powerful enough to heat the forge to the right temperature, especially since this forge is a simple open-top design.

I have cured the fire cement by lighting a small fire in the forge and allowing it to burn for about two hours. After some rain, I noticed that the cement seems to lose it’s hardness. It seems that it is certainly not waterproof, so the forge will need to be covered when not in use.

I need to get two more fire bricks to finish off the forge.

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Metalworking Forge

I am constructing a metalworking forge to make a small knife.

I am planning to use fire cement and bricks to make the frame of the forge, and a 2 inch steel exhaust pipe tube with a 12v fan for air.

I will be using regular coal or charcoal for the fuel.

I am planning to use Damascus steel to make the knife, I should be able to get the forge hot enough to melt this type of steel.

The most difficult part so far has been finding the parts to build this. I have had to make educated guesses as to how powerful the fan needs to be, how long and how thick the air inlet needs to be, how much fire cement I need, etc etc. I think trial and error is common in homemade forge building, however.

I will post updates as I progress in this project.

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P-158 DataVault II: Directional Antenna Construction

The DataVault Project that I am working on is intended to store data for a long period of time. Since the location of the DataVault could easily have been lost or forgotten over the years, the device will need some kind of radio beacon or transponder to allow it to be located.

I intend to use a simple long-range transmitter for this, with a directional antenna. The device would be programmed to emit a pulse from the transmitter at regular intervals, after a certain period of time has elapsed.

I have wired up an antenna that I built for a previous project to a transmitter and receiver, in order to evaluate the effectiveness of it’s direction finding abilities. The antenna is a Yagi, built for 433 MHZ.

This antenna did not function particularly well as a directional antenna in the previous project it was used in. I believe this was due to poor impedance matching between the antenna and the cable. I have shortened the cable as much as possible to try to alleviate this, hopefully it will have at least basic direction finding abilities now.

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