Converting a Lawnmower Engine To Run on Compressed Air

Our most likely exposure to a steam engine these days will probably come courtesy of a railway locomotive. A machine capable of immense power and probably with significant complexity and engineering  in its construction, something the majority of us will only ever be able to see at second-hand. But there was a period when steam engines were much more accessible, before internal combustion engines and electric motors took on the task of automating hard work you would have found small stationary steam engines in all corners of industry.

These engines are on a scale much more easily embraced by hackers and makers, and though vintage stationary engines are thin on the ground these days there are a significant number of people pursuing their construction by converting modern petrol and diesel engines to a more old-fashioned medium.

[Lindsay Wilson] has a lawnmower engine which a few years ago he converted with the addition of a sleeve valve to run on compressed air. It’s not a steam engine because creating a safe and legal steam boiler is an expensive process, but despite this it amounts to the same thing. The engine in question is a small sidevalve single cylinder Suffolk Punch lawnmower engine from which he has removed and blocked the valve gear, and added a sleeve valve powered by a linkage from the crankshaft and using the spark plug hole as an inlet and outlet. He provides a lot of detail on the sleeve valve’s construction, and it really is a surprisingly simple arrangement. We might look for a harder metal than copper pipe for the guide in which it runs though.

The video below the break shows the engine being run up after a period of storage. It’s an effective device, easily capable of taking more air than his compressor can supply.

Continue reading “Converting a Lawnmower Engine To Run on Compressed Air”

Effortlessly Send Antenna Wires Skywards With A Spud Gun

The heroes of action films always make it look so easy. Need to climb a tall building? Simply fire a grapnel hook from a handy harpoon gun, it’ll always land exactly where you want it and gain a perfect purchase so you can shin up the rope and arrive at the top barely having raised a sweat. If Hackaday ran Q Branch, we can tell you, we’d make ’em work a bit harder. If only because nobody likes a smartass.

If you’ve ever had to get a real line over something tall, you’ll know it’s a lot more difficult than that. You can only make it work with the lightest of lines that you can then use to pull up something more substantial, and you would be amazed how poor a thrower you are when you’re trying to throw upwards. Try attaching fishing line to a weight, try a bow and arrow, and nine times out of ten you won’t make it. There’s a serious amount of skill and luck involved in this line-throwing game.

[WB5CXC] has an interesting solution to this problem, at least as far as the application of throwing antenna wires over tall obstacles. He’s made a spud gun from PVC pipe, powered by compressed air. It takes the form of a U-shaped tube with one side of the U being a pressure vessel separated from the other by a ball valve.. Place a close-fitting puck with your wire attached in the open side with the valve closed, pump the pressure vessel full of air with a bicycle pump, and open the valve to send both puck and wire skywards. He says it will clear 100′ trees, counsels the user not to go higher than 100psi, and warns that the speeding puck can be dangerous. We like it already.

We’ve covered many spud guns here at Hackaday in the past, but it seems this is the first wire launching one. We’ve had a steam one for example, or this bolt-action spud gun, but pride of place has to go to the spud gun to end all spud guns.

Via DXZone.

3D Printing Compressed Air Tanks

Using PVC pipe as a pressure vessel for compressed air can be a fun and enjoyable hobby. It’s safe, too: while there are are reports of PVC pipe being the cause of accidents, these accidents include a black powder potato gun[1], and welding too close to a PVC pipe containing compressed air[2]. Compressed air stored in a PVC pipe is never a proximal cause in any accident, and the OSHA’s Fatality and Catastrophe Investigation Summaries bear this out; there was no industrial or occupational accident recorded in these summaries where a pressure vessel made out of PVC was the cause of any injury or death[3].

Although PVC pipe can be a perfectly safe, effective, and cheap pressure vessel for hobby applications, it’s not always the best choice. A group of students in Renens, Switzerland are building autonomous robots for the Eurobot competition, and this year’s robot uses pneumatics. That means compressed air, and that means a pressure vessel. Since just about everything else on this robot is 3D printed, they asked the obvious question. Is it possible to 3D print a tank for compressed air?

The tank for this robot would only be used up to about 4 bar (400kPa), and after a few quick calculations, the team discovered the wall thickness – even in a pressure vessel with corners – would be pretty low. The first prototype, a 40mm cube with 20% infill and a hole drilled in the side, held 6.5 bar (650kPa) for an hour. This success didn’t last, though: he second prototype, a 65x40x80mm rectangular prism printed without as much infill, exploded at 5.5bar (550kPa).

The third time’s the charm, and with filleted ribs inside the tank, the third prototype was able to hold pressure up to 6.5 bar. Of course no 3D print is perfect, and the third prototype did leak, but a bit of acrylic spray paint applied to the outer surfaces held the air in.

While it’s not as fun, easy, cheap, rewarding, or safe as using PVC pipe as a pressure vessel, the team did manage to build a 3D printed pressure vessel with a custom shape. You can’t do that very easily with round pipe. And 3D printing opens up all manner of internal structure to experiment with. We’d like to see this developed even further!

Sources: [1], [2], [3]

Introducing the Solder Sucker 9000

Using a regular plunger style solder sucker is tedious at best, and usually not that effective. If you’re trying to salvage components off a PCB, sometimes it can take longer than it’s worth to do — short of reflowing the entire board that is! But what if you had something to desolder individual components faster?

After getting fed up with his cheap plunger-based solder sucker, [electro1622] decided to try a different tactic. He reuses components from old PCBs all the time, so he tried something a bit unorthodox to remove them. Compressed air.

Now let’s just preface this with it will be messy, so you might want to set up a box to catch the removed solder. Simply use your iron of choice to heat up the solder globs holding back your components, and then blast it with compressed air out of a small nozzle. Way faster than a solder sucker.

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Ultra-powerful Pneumatic Hand Dryer

Have you been let down by the inadequate performance of a hand dryer? We know that feel. [tesla500] recently installed a centralized compressed air system and decided he might as well do something interesting it, so he built an ultra-powerful hand dryer that rivals the performance of any hand dryer on the market.

[tesla500] set out to make a clone of the Dyson Airblade. He started out with a simple prototype out of milled aluminum with one nozzle. Even with just one nozzle the hand dryer performed incredibly well. Next he designed a Solidworks model with a smaller nozzle gap (50um) and 4 total nozzles which has even better performance and emulates the airflow of the Airblade.

The dryer was originally controlled with a foot-activated pneumatic valve, but it severely restricted airflow. [tesla500] decided to use a 3/8″ solenoid valve instead, which solved the airflow restriction. According to [tesla500], the dryer works even better than the Airblade when running at full pressure, although he notes that you might need to watch out if you have any open wounds on your hands.

Mexican law enforcement seizes a hacked together Weed Cannon

marijuanna-cannon

Here’s an interesting hack. It’s a small pick-up truck with a Dope Cannon attached to it. Sure, it looks more like something you’d see in Syria, but this item was actually seized in Mexico where it was being used to fire 30 pound slugs of Marijuana over the border fence with the US. Usually when you fire artillery there isn’t someone on the target range trying to recover the projectile!

The device uses a PVC barrel to guide the pot-pellet as it’s propelled by compressed air. Hey, swap out the drugs for an energy drink and that sounds pretty familiar. Our qualifying entry for the 2012 Red Bull Creation Contest was an energy drink cannon which  used the same setup with a slightly smaller caliber. It makes us wonder if the drug cartel uses little parachutes like we did?

Doesn’t it arouse suspicion to drive something like this around town? You’d think they’d use a box truck or something similar to hide the giant gun.

[Photo Credit: AP via NY Daily News]

[via Reddit]

Heatless compressed air dryer

The pressurized air from a standard air compressor is fine for most uses. But some applications like plasma cutting call for low-humidity air and the hardware available to facilitate this can cost a bundle. [Roland] and his cohorts at TX/RX Labs (a Houston, Texas Hackerspace) just built this air drying system.

It works using a desiccant; a substance that sequesters moister. It’s the stuff in those little packets you find in shoe boxes and the like with a warning that you shouldn’t eat it. The image above shows two chambers which house the desiccant. Only one is used at a time, so that as it’s ability to remove moisture drops, the system can switch over to the other chamber. There’s even an automatic recharging system built in that uses a portion of the dried air to remove the humidity from the unused desiccant chamber.

There’s a functional diagram at the link above. It’s resolution is low enough that the text is almost unreadable but we’ve asked [Roland] if he can repost the image. This seems like a build in which other hackerspaces will be interested.