The joys of compressed air (by alaric)
I've always had a hankering for pneumatic tools. The idea is that compressed air is used as a power source for hand tool, rather than an electric motor. This has various advantages - the tool is lighter (motors are heavy), it's safer (electric motors, when stalled, produce a sharp increase in torque that can make the thing break your wrist if you're not lucky, and the motor can then burn out), and it's cheaper (air drive thingies are cheaper than motors) and simpler. This makes a wider range of tools practical and affordable, from drills and power screwdrivers to stranger things like pneumatic files and caulking guns. And compressed air has some unique uses, too - tyre inflaters, blowers for clearing dust away, and spraying liquids for painting or cleaning.
The downside, however, is that you need a source of compressed air. Thankfully, these have been getting more popular in the hobbyist market, and therefore cheaper, and got a bonus from work, and I've wanted one for years, and so, POW! I now own an air compressor!
It's only a small one. I spent just over a hundred pounds, which is more than I've spent on something purely for fun (it's a tool, but not one I need) in ages. I picked up a set of basic air tools with it - a tyre inflater, a blower, a paint sprayer, and a wash sprayer. Sarah's keen on using it to paint things, so once she's had a go with the spray gun, I'm planning on getting her a more artist-grade air brush with fine controls, and she's getting me a pneumatic ratchet (that can do and undo screws and bolts) as a first "proper" tool.
I'm very tempted by a pneumatic nail gun, because they can drive a nail into wood in a single "phut" compared to having to hammer one into place (and the ever-present risk of it going wonky halfway through), which is a huge labour saver - but I don't actually use nails all that often. Perhaps in the next round of workshop roof fixing...
I thought it was broken when I first unpacked it; the manual had a series of steps to follow when first setting it up, and when switching it on (check the crankcase oil level, set the valves to a safe position, etc) - I followed them all and turned the power on, and the motor started roaring away and the tank pressure rising. But the pressure wouldn't go above two bar, and when I turned the motor off, all the air hissed out again. It was getting late so I got ready to go to bed rather than playing more, but while flicking through the manual's troubleshooting section (it looked like a failure of the non-return valve or the safety valve, and I resolved to check both in the morning), I noticed that the instructions for AFTER you've used the compressor included opening a cylinder drain valve to let out any condensation... I felt underneath and, sure enough, the drain valve was wide open! Checking that's closed should be part of the starting process, but wasn't in the instructions...
In the meantime, I've been having fun with the kids making balls levitate in the air stream from the blower 🙂 We can float a ball-pond ball a good twenty to thirty centimetres above the blower nozzle, at an angle of up to forty-five degrees. and 1.5bar; when I have a face shield on and no children crowding around I might try cranking the output pressure up to the full 6-8bar the machine can produce and see if I can float balls at steeper angles, or heavier objects...
Sun 11th May 2014 10:48 am 
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By alaric, Tue 13th May 2014 @ 10:06 pm
Sarah bought me that pneumatic ratchet today, and I bought her the air brush 🙂
It's a 3â„8" drive pneumatic ratchet, and a attached a mini oiler to the air inlet. Pneumatic tools with moving parts need lubrication, and that lubrication is conventionally delivered via the air stream. You can get a thing that goes on the compressor to put a fine mist of oil into the air stream, but as I want to use the same hose to drive non-mechanical tools such as tyre inflaters, spray guns, and so on, that don't need oil and to which it would be a contaminant, I didn't do that. Mini oilers screw into the air inlet of the tool, and the air supply then screws into the other end of it; they simply slightly extend the length of the tool. Mine has a clear plastic body so I can see how much oil is sloshing around inside and know when it needs refilling.
Turns out it's really hard to get the oil in. You have to undo a small screw to reveal a small hole, and the oil just wants to bridge across the hole and seal the air in so the oil won't flow down. I managed to force it in without too much mess using a small plastic syringe.
Anyway, I tried it out this evening (before it got too late to run compressors) and it runs nicely. Not that I have anything that needs ratcheting right now; the function of a ratchet is to turn things around, normally hexagonal nuts, but you can get all sorts of stuff that goes onto a 3â„8" square drive socket. I plan to obtain an adapter for standard 1â„4" hex screwdriver bits, and use it as a crude pneumatic screwdriver as well.
The funny thing is, this doesn't let me do anything I couldn't otherwise do - I have a manual ratchet, and can inflate tyres with my foot-pump, and can paint things with a brush. Ok, the blower that just produces a stream of air is something new, but doesn't exactly fill a huge gap in my technical capabilities. But I'm really excited about it all because it's something I've always wanted, purely because it's nice. The technology of pneumatic drive is good, so I like it for its own sake. It's a new thing for me to learn about. It's new gadgets I can fiddle with. For so long I've not been able to afford things I can't find a good justification for, so this means a lot to me.
By alaric, Tue 13th May 2014 @ 10:17 pm
Oh, by the way, another technology I am fond of is the Torx screw head. Turns out you can get 3â„8" drive torx drivers and all sorts of torx-head screws...