Shifting gears on your pig roasting spit


[Tim] and [Jon] have a hankering for some pork product of their own making. Your average residential kitchen is ill-equipped to handle an entire pig, so they got down to business building this pig spit out of old bicycle parts.

The main components in the project are two stands built out of square tube which go on either side of the cooking fire (coal bed?). They include bearings to support a horizontal bar on which a pig carcass is somehow mounted. The whole point of a spit is to turn it while cooking, and that’s where the gear system comes in. The front crank from a bicycle was welded onto the spit, with one pedal still in place. This way if the motorized system breaks down they can still turn the thing by hand.

The crank connects to the cogs with one chain, while the other chain connects the cogs to a windshield wiper motor. When connected to the specified 12V it turns around 6 rpm; close but a bit too fast. After some trial and error they found a 5V supply turns it at the optimal 2 rpm.

We wonder if you can put a whole pig in a meat smoker?

Continue reading “Shifting gears on your pig roasting spit”

Over engineering windshield wipers to sync to music

In the late 90s, Volkswagen aired a series of awesome television advertisements that won a few awards relevant to those in advertising circles. One of these ads was titled Synchronicity and showed a VW Jetta’s windshield wipers (among other things) syncing to music as the car drove down a rainy alley. [ch00f] thought beat tracking wipers would make for a great project, and we love the sheer amount of engineering that went into this build.

The build began with [ch00f] taking apart his wiper motor to get some specifics for his build. Ideally, a rotary encoder would be very useful for this project, but designing a durable encoder would be a pain anyway. [ch00f] had to settle with the ‘parking pins’ on the wiper gear motor that allow the wipers to be driven in intermittent mode.

[ch00f] spent a great deal of time writing code that would guarantee a constant wiper speed, but that didn’t solve the problem of phase, or having the wipers begin or end their cycle on the beat. This problem was somewhat solved (as you can see in the video after the break) by using a feed forward system – basically, the software would predict the change in phase needed and correct it by changing the speed.

The build still isn’t perfect, although that’s mainly due to the placement of wiper parking switch on the wiper motor. [ch00f] plans on spending a little more time correcting the wiper speed/phase control with software, but what he’s got now is still very impressive.

Continue reading “Over engineering windshield wipers to sync to music”