Few consumer-grade PCs are what you’d categorize as built to last. Most office-grade machines are as likely as not to give up the ghost after ingesting a few too many dust bunnies, and the average laptop can barely handle a few drops of latte and some muffin crumbs before croaking. Sticking a machine like that in the shop, especially a metal shop, is pretty much a death sentence.
And yet, computers are so useful in the shop that [Lucas] from “Cranktown City” built this neat industrial-strength monitor arm. His design will look familiar to anyone with a swing-arm mic or desk light, although his home-brew parallelogram arm is far sturdier thanks to the weight of the monitor and sheet-metal enclosure it supports. All that weight exceeded the ability of the springs [Lucas] had on hand, which led to the most interesting aspect of the build — a pair of pneumatic locks. These were turned from a scrap of aluminum rod and an old flange-head bolt; when air pressure is applied, the bolt is drawn into the cylinder, which locks the arm in place. To make it easy to unlock the arm, a pneumatic solenoid releases the pressure on the system at the touch of a button. The video below has a full explanation and demonstration.
While we love the idea, there are a few potential problems with the design. The first is that this isn’t a fail-safe design, since pressure is needed to keep the arm locked. That means if the air pressure drops the arm could unlock, letting gravity do a number on your nice monitor. Second is the more serious problem [Lucas] alluded to when he mentioned not wanting to be in the line of fire of those locks should something fail and the piston comes flying out under pressure. That could be fixed with a slight design change to retain the piston in the event of a catastrophic failure.
Problems aside, this was a great build, and we always love [Lucas]’ seat-of-the-pants engineering and his obvious gift for fabrication, of which his wall-mount plasma cutter is a perfect example.
And now a POV AR display! Moving the monitor at full speed……
I absolutely like this guy’s entertaining projects.
I look forward to a potential sequel when he will eventually make a fail-safe upgrade with spring power and compressed air release.
I really like the style and narrative of their videos <3 But honestly I wouldn’t feel particularly safe next to a 50kg steel arm that just drops when there is a leak
Agreed, it should be normally locked when “unpowered” and only release when pressure is applied.
That is how Geo. Westinghouse designed his railroad air brake system – Patent in 1869
The system is charged to release. Built-in safety.
https://en.wikipedia.org/wiki/Railway_air_brake
I agree.
It also would not have been too difficult to mount the springs in such a way that they always balance the arm good enough that a bit of friction can do the rest. No compressed air needed.
Have a look at how the springs are mounted in the (Ikea and others) desk lights. The spring forms an overcenter in the mechanism, so regardless of spring tension, it does not get pulled in any direction when the arm is vertical, and spring tension is maximum when the arm is (very near to) horizontal. If the arm gets bent further (if there are no mechanical stops) spring tension would reduce again.
Similar mechanism are used for much heavier and longer camera booms.
And as also used in camera booms, counterweights are also an option.
But for pneumatics, adding a heavy duty locking spring and having the cylinders push the spring from the locking mechanism is also just a small increase of complexity, and a bunch safer. I usually turn off compressed air when I leave the shop anyway, because it always leaks a bit. You may also want to use your compressor on other locations sometimes, and your monitor falling down because of this would also be bad.
Wrong link.
Embedded video is correct, this link is going to a dead fluke, featured also on HaD
The part about the mechanism is good. A computer seems like a pretty terrible candidate for mounting this way, but you can think of lots of uses for a mechanism that lets you easily stow heavy equipment overhead.