From Foot Pump Cylinders To Pneumatic Robot Fighting Arm

Halfords Essentials foot pump
Halfords Essentials foot pump

[James Bruton] is well known for making robots using electric motors but he’s decided to try his hand at using pneumatics in order to make a fighting robot. The pneumatic cylinders will be used to give it two powerful punching arms. In true [James Bruton] fashion, he’s started with some experiments first, using the pneumatic cylinders from foot pumps. The cylinders he’s tried so far are taken out of single cylinder foot pumps from Halfords Essentials, costing only £6.29, around $8.11 US. That’s far cheaper than a commercial pneumatic cylinder, and perfectly adequate for this first step.

He did have to hack the cylinder a little though, besides removing it from its mounting and moving it to a DIY frame. Normally when you step down on a foot pump’s lever, you compress the cylinder, forcing air out the hose and into whatever you’re inflating. But he wanted to push air in the other direction, into the hose and into the cylinder. That would make the cylinder expand and thereby extend a robot fighting arm. And preferably that would be done rapidly and forcefully. However, a check valve at the hose outlet prevented air from entering the cylinder from the hose. So he removed the check valve. Now all he needed was a way to forcefully, and rapidly, push air into the hose.

For that he bought a solenoid activated valve on eBay, and a compressor with a 24 liter reservoir and a decent air flow rate of 180 liters per minute. The compressor added £110 ($142) to the cost of his project but that was still cheaper than the batteries he normally buys for his electric motor robots.

After working his usual CAD and 3D printing magic, he came up with an arm for the cylinder and a body that could fit two more valve activated cylinders to act as a working shoulder. A little more 3D printing and electronics, and he had 3 switches, one for each valve and cylinder. He then had the very successful results his experiment. You can see the entire R&D process in the video below, along with demonstrations of the resulting punching robot arm. We think it’s fairly intimidating for a first step.

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Push Button, Receive Beverage!

Here’s a rec-room ready hack: an automatic drink dispenser.

[truebassB]’s dispenser operates around a 555 timer, adjusted by a potentiometer. Push a button and a cup pours in a few seconds, or hold the other button to dispense as much as you want.

The dispenser is made from MDF and particle board glued together, with some LEDs and paper prints to spruce it up. Just don’t forget a small spill sink for any miscalculated pours. You needn’t fret over the internals either, as the parts are easily acquired: a pair of momentary switches, a 12V micro air pump, a brass nozzle, food-safe pvc tube,  a custom 555 timing circuit — otherwise readily available online — a toggle switch, a power supply plug plus adapter and a 12V battery.

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This Hackaday Prize Entry Sucks

Sucker [K.C. Lee] is busy working on his entry to The Hackaday Prize, and right now he’s dealing with a lot of assembly. For his entry, that means tiny SMD parts, and the vacuum pen he ordered from DealExtreme hasn’t come in yet. The solution? The same as anyone else who has found themselves in this situation: getting an air pump for an aquarium.

For this quick build until the right tool has time to arrive from China, [K.C.] took an old fish pump and modified it for suction. He doesn’t go over the exact modification to the pump, but this can be as easy as drilling a hole and stuffing some silicone tubing in there.

The ‘tool’ for this vacuum pen is a plastic disposable 0.5mm mechanical pencil. [K,C.] found this worked alright on smaller parts down to 0402 packages, but heavy parts with smooth surfaces – chips, for example – are too much for the mechanical pencil and aquarium pump to handle.

Any flavor sports drink at the push of a button

[Sage Spate] wasn’t happy with the boring flavors of orange, blue, or red sports drinks. He decided to mix it up by building this flavor-mixing drink dispenser.

He modified the caps for each bottle to work with an air-pressure system. This way the bottles themselves serve as the reservoir and can easily be replaced when empty. Each cap has two openings, one is used by the dispenser nozzle and includes a hose that will reach all the way to the bottom of the bottle. The other hole connects to an air pump. Raising the pressure in the bottle forces sports drink up and out of the dispenser hose.

One air pump is used for all three reservoirs with a set of solenoids to enable each flavor individually. [Andreas] sent in the tip and mentioned that some of the parts are salvaged from an ink jet printer but we’re not sure which ones. At any rate, the next step in the project is to add Arduino control which will allow for custom mixing based on preset recipes.

We’ve embedded the demo video after the break.

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