How a simple mechanical system knows when your tires are low

Anyone who has been reading my posts will have surmised that I like clever mechanisms. The Bourdon tube, which is the source of the pressure gauge's magic, certainly qualifies.

The operation is simple. One end of the curled metal tube is sealed and the other is connected to the source of the pressure to be measured. As that pressure increases, the tube expands and straightens very slightly, as if being inflated, which, essentially, it is. As it straightens, the sealed end moves and pulls on the attached mechanical linkage of gears and levers.

Through that gear train, the slight movement of the tube is translated into rotation of the indicator needle. The tube, gear train and gauge face are sized and calibrated such that the amount of tube movement for a given applied pressure will move the needle to indicate that same pressure on the face of the gauge.

Simple and clever. Almost like magic.

For your bigger stapling jobs

The machine does not use staples as we know them in the common desktop stapler. It has a spool of wire, lengths of which it punches through the materials being bound, folds twice, and cuts. As the Stitcher model name suggests, it functions like a sewing machine for wire staples. One stomp on the foot pedal produces one staple, the length of which can be controlled by the configuration of some parts inside the head of the machine. Move the materials to be bound along and step on the pedal again.

Like last week's Graphotype, this machine is approximately a century old. Unlike the Graphotype, the principal action used is still basically how wire stitching is done today.

Cheers to commenter The Adama for being the first with the most specific response--your Stanley Fatmax tape measure is on its way! Stay tuned for more mystery tools next week.

A micrometer helps you measure more stuff down to 1/10,000 of an inch

Like the vernier calipers, micrometers use the simple fact of arithmetic that 40 * 25 = 1000 to great advantage. Lets look at how.

The "40": The essential element of a micrometer is a threaded shaft with a thread pitch of exactly 40 threads per inch. Thread pitch refers to the measurement of the number of threads in one inch on something that is threaded, like a bolt, or the shaft in a micrometer. In the case of the micrometer, this 40 tpi thread pitch means that one full revolution of the shaft will move it in or out exactly 1/40th of an inch.

The "25": Full revolutions are further divided equally into 25 divisions. Each full revolution of the shaft of the micrometer entails 24 marks indicating 25 divisions passing the fixed line (lets call it the "zero" point) on the body of the micrometer.

So, if each revolution of the handle is 1/40th of an inch and each mark passing the "zero point" on the body of the tool represents 1/25th of each of those revolutions, then it follows that each mark passing the zero point represents 1/25 * 1/40 = 1/1000 of an inch. Hence the 1/1000" accuracy of a micrometer.

There are versions of the micrometer that include a 10-division vernier scale on the sleeve of the tool. Using this vernier scale, the micrometer can provide accuracy to another order of magnitude, 1/10th (because it is a 10-division scale) of 1/1000th or 1/10,000th of an inch.

As with so many things, using the micrometer is far simpler than the math behind of its operation might suggest. Simply turn the handle, or thimble, of the micrometer until it is positioned snugly against the item to be measured. Micrometers often include some form of torque clutch on the handle which will begin to freewheel after the thimble has been tightened sufficiently.

With the thimble in position, read the measurement. First, read the number of full divisions showing on the sleeve. Each division corresponds to one full revolution: 1/40th of an inch or 0.025-inch. To aid in reading the tool, every 0.1-inch is typically also marked. In the micrometer pictured here, the reading in this step is 0.125-inch. Next, read the scale marked on the thimble. The numbers on this thimble correspond to 1/1000th of an inch, or 0.001-inch. In our example, this is 14 or 0.014-inch. To obtain the full measurement, simply add these two readings; 0.139-inch in this example.

For a micrometer with a vernier scale, as in the micrometer pictured below, the next significant digit (0.0001) is read from the first line on the thimble to directly align with a mark on the vernier scale.

It should be noted you need to periodically calibrate micrometers to ensure that the measurement they provide actually corresponds to the standard version of that measurement in the real world. And it's worth noting that these tools are more delicate than vernier calipers.

To learn more, a great reference is "The Starrett Book For Student Machinists."

An easy way to send a TV signal anywhere

An internet search reintroduced me to the venerable Ramsey Electronics. The Web site brought a smile to my face with things like a DTMF decoder and relay board, broadcast-quality FM transmitters and, to my delight, a short-range TV-transmitter kit, the TV6C. The kit cost $39.95 and arrived quickly. The quality was good—great, actually, as compared to many of the things I've seen imported from Hong Kong with untranslated instructions. The only issue was that both of the kits I ordered came with an extra capacitor of around 22 uF and were short one resistor of around 22 kOhm. Fortunately, I actually have a parts drawer with spare 22kOhm resistors in it.

Building the kit was one thing. Trying (and failing) to test it and our bodies to destruction was quite another. While the video quality was never spectacular, the transmitters managed to hold their tuning and to hold together despite being completely pummeled. Video from the lipstick cameras aimed at our bouncing helmeted heads broadcast continually to the TV monitors in the audience. The external antennas we used did not survive, but none of the abuse was able to destroy the transmitters themselves.

(If it sounds like I'm being cagey about the project for which we used these transmitters, it's because I am. It isn't quite ready to release yet, but keep an eye out for it soon.)

Mail order electronics kits have come an awfully long way in recent years and now offer the ability to add really useful, significant functionality to projects. Without even considering the rest of the vast array of kits on the market today, think about the possibilities of just an easy to build, affordable TV-transmitter kit. And with the digital-TV switchover, piles of free TV monitors are there for the asking.

Now I'm looking at the ICI1C - Infra-Red Switch Control Interface Kit. Is anyone else getting ideas for using some kits as a component in an upcoming project? Tell us about it in the comments.

Tell us what this machine is and win a Stanley Fat Max tape measure

Here's how it works: We post a picture of a strange object from my shop, maybe a clue or two, and you guess what it is in the comments section below. The first and most precise among you to guess correctly will win the prize. This week, it’s a 30-foot Stanley FatMax tape measure. Pretty sweet.

This week, the obscure object is something I was given by a company that had gone out of business. What kind of work did that company do, and for what was this machine used?

Good luck!

An Ohio inventor's cargo box has drawn interest from major shipping companies, but now faces years of FAA review

The Columbus Dispatch brings the story of Scott Farrar, owner of the small Ohio company Farrar Scientific. His reinvented "PharmaPort" cargo box uses a "passive" technology to keep drugs and other products at a constant temperature, and can fit anywhere on a cargo plane. Small battery-run fans help circulate air within the boxes, rather than the usual "active" compressors or heaters

Trade show appearances created a buzz among shipping companies, and UPS has already expressed interest and run Farrar's invention through a series of tests. But the FAA could not decide whether the invention counted as a "passive" system, and has now decided to write an entirely new policy for the invention. That means Farrar faces a waiting time possibly as long as three more years, on top of almost a year spent talking with the FAA.

That delay could mean life or death for the small company that is already down to seven employees from a high of 17. Farrar says that he would immediately hire up to 25 employees upon getting FAA approval, and in time could employ up to 150 people.

We, of course, love to recognize such local inventions during its annual Inventions Awards, and we even follow up on our winners' latest activities. So it's a bit heartbreaking to see when an invention that appears technologically and commercially sound might falter in the final stages of a regulatory process.

Farrar plans to meet with FAA officials in Washington this month to try and persuade them to ditch the new policy approach, and he has also gained some support from Ohio senator Sherrod Brown. We'll keep our fingers crossed.

[via Columbus Dispatch]

How to build complicated equipment you can operate while being shot at

Thinking about how equipment gets used by the military, the need for good design should be obvious. People who are not necessarily guaranteed to have any particular higher education are going to have to operate some fairly complicated equipment, possibly while in the dark, possibly while in the rain, and possibly while being shot at. And it's entirely possible that said equipment was just parachuted out of a plane or used as a jack stand (I'm convinced that an AN-GRR-5 radio in it's original case could stand up as one).

Leaving aside the cost issues, I like to look at these pieces of equipment as a design study: How to build something that will be easy to operate and will continue working in almost any conditions. Doesn't that sound like a reasonable set of design goals for any type of equipment? While cost is certainly a very real factor, I view military design as a call to action for lazy or just plain bad designers using it as an excuse across the board.

As for where to find the gear, try local surplus stores (these can be a hit or miss affair), hamfests (if it is radio-related equipment), or ebay, which is where I picked up the phones and the shortwave in the photo gallery. When you want say, 10 pallets of surplus, check out GovLiquidation.

Share your favorite military surplus equipment and the best places to shop for it in the comments and on the PopSci Flickr pool.

Plastic containers saved my life

As the collection of "stuff" has grown over the years, the methods of organization have evolved. Open shelves with piles of junk quickly failed for the obvious reasons—it is hard to keep things of odd shapes and sizes piled on the shelves and everything is exposed to all of the dust and mess in the shop. After a certain weight threshold, shelves seem to collapse. Later, I used coffee cans and surplus wooden bins (some of which I still keep as mementos from the venerable and sadly expired Fertik's electronics surplus store in Philadelphia). The coffee cans and boxes first lived on shelves, and later migrated into a mix of shelving and salvaged filing cabinets. This was better because things were better compartmentalized, labeled, and protected, but still had its shortcomings. One major issue was the amount of effort involved in re-allocating storage. If the pipe fittings drawer became over crowded for example, I would logically try to annex the next drawer in the filing cabinet. Typically, however, that drawer would already be filled, necessitating further re-organization. While such operations did give me a chance to become re-acquainted with our junk and to periodically purge the collection, for the most part they just burned valuable time.

In the new shop, we have a whole room for storage. (Queue chorus of angels.) We built the cheap 2x4 and plywood equivalent of pallet shelving and populated it with two sizes of Rubbermaid "Roughneck" totes. Lighter but bulky items go in the bigger totes (18-gallon size) and smaller and/or heavier items end up in the smaller ones (10-gallon size). There are still a few classes of items in storage that would be better served by a storage cabinet with divided drawers such as the Stanley Vidmar series of cabinets, but for things like my collection of Western Electric model 500 rotary phones and the stash of surplus fabric, this is a great solution. The smaller size totes are of the same width and length and are just over half the height of the larger totes. As a result, one large tote or two smaller totes stacked will fit into approximately the same space, which simplified both the construction of the shelves and the organization of the bins.

Among the advantages of this system are a decent measure of protection from the surrounding elements, ease of re-ordering and re-organization, ease of expansion of the overall storage system, and my favorite: the ability to bring the totes to where they are needed around the shop. Secondary advantages include the ease with which these can be stacked on pallets and in trailers for transport. On occasion, we bring some of our contraptions to events, and the ease of loading and transport with these bins is unparalleled. I also expect to reap significant time savings in the next shop move.

There are still some disadvantages to this storage scheme. There is a significant amount of empty space being wasted in most of the containers, which is essentially by design; were they filled to the top, they would be very difficult to pick through. If we didn't have a substantial amount of space devoted to storage, this solution would not fit our needs as well. The bins are also fairly expensive, especially considering the simplicity of their construction. I have been paying around $5-$7 apiece.

I suspect we'll continue with this mode of storage for some time to come for the items too bulky, plentiful, or infrequently accessed to merit placement in a storage cabinet closer to the center of the action in the shop. If I find a decently priced source of clear plastic totes that fit within the same size assumptions built into our shelving, I may gradually transition to those.

Whatever the situation in your shop, I recommend giving serious consideration to how this sort of plastic tote can help your organizational situation. In my next post on this topic, I'll look at storage options to replace my filing cabinet filled with coffee cans full of sorted fasteners.

The classic 1979 Atari videogame is transformed into three dimensions

To enhance the retro look, Sharp suspended the lander from a moving carriage with the fishing line. As the line unspools and the lander descends, the player turns a modified car steering wheel to rotate the module and then hits a button to fire the “rockets” and push the craft in the direction it’s pointing. The line spools up, and printer motors shift the carriage along a track, carrying the lander across the moonscape.

Sharp tested magnets as a means of measuring successful touchdowns but found that they pulled the lander right to the target, making the game too easy. Instead he installed touch sensors to measure when the craft hit the ground and wrote software that estimates its exact position based on how far the motors moved in the course of the game.

Still, the game, which is installed at the Southwold Pier in Suffolk, England, doesn’t demand perfection from its players. “You can get away with a few little mistakes,” Sharp says, “which is kind of like the real thing.”

How the Real Life Lunar Lander Recplica Works
Time: One year
Cost: $800
MISSION CONTROL
A science-fiction-sounding mission operator delivers flight directives, such as “Land more slowly!” Sharp provided the narration at first but then recruited British radio personality Emma Freud to do it instead. In exchange, Sharp promised to build her a version of his first “real” arcade game—a mash-up of the classic game Pong and exercise bikes, called Cyclepong.

BRAINS
A pair of old PCs, bought for about $30, translates the input from the controllers—a button that controls thrust and a steering wheel—into the lander’s movements. Sharp wrote the software and, despite its school-science-project appearance, the game is very responsive: The main PC sends instructions to the motors 50 times per second.

GAMEPLAY
The computer measures success by the lander’s descent rate and its final position relative to the targets. Three successful landings earn players one of a variety of vintage-looking pin-on buttons featuring Apollo-themed images. But neglect to fire the rockets in a timely fashion to slow the lander down at a safe pace, and you’ll drop too fast and crash. Crooked landings, measured by how much the servo motor that rotates the lander has moved, are also considered failures. Red LEDs flash and the game’s speakers blare sounds of explosion, letting everyone around you know that you’ve disappointed the nation.

The H2Whoa Credo: DIY Can Be Dangerous
We review all our projects before publishing them, but ultimately your safety is your responsibility. Always wear protective gear, take proper safety precautions, and follow all laws and regulations.