After a long December of hand-coating chocolates for relatives last year, [Chaz] decided that enough was enough and built a chocolate enrobing machine to do the dirty work for him. As a side project, he built a rotary tumbler to chocolate-coat things like wasabi peas, which we assume are designated for [Chaz]’s enemies.
This build started with an off-the-shelf chocolate fountain for which [Chaz] designed and printed a new nozzle in PLA. He also knocked off the flutes that make it fountain on the band saw and removed the rest of the material on the lathe.
The conveying bit comes from a conveyor toaster oven that [Chaz] had lying around — he removed the conveyor and hooked it up to a motor from his collection using a slightly modified flex coupler.
With the chocolate enrober complete, [Chaz] moved on building to the rotary tumbler, which is made from two thrift store pans hammered together at the edges and connects up to the front of a KitchenAid mixer. The final verdict was that this did not work as well as the enrober, but it wasn’t a complete bust — wasabi peas (and most of the kitchen) got coated in chocolate.
While we’re not sure we’d use that PLA chocolate pump more than once, we sure would like to enrobe some things in chocolate, and this seems like a good way to get it done. Check out the build video after the break.
Your [Bornhack] plans include leaving lemons in patterns as an info display. Your squirrel feeder needs to only dispense nuts when the squirrels deserve it. As promised last week, an intro to gating, feeding, and moving bulk material.
Gates
Bulk material flow needs control. Starting is easy, it’s stopping that’s hard.
Dump Gate, Slide Gate, Clamshell Gate
If your need is just to dump out the entire contents of the bin, a dump gate works – a trapdoor with a latch. If you need to stop before emptying the bin, you can use a slide valve – a flat piece of material in a box that slides in and out. Friction from material bearing down on them causes large open/close forces. Material can jam between the flap and the housing when closing.
A variation is the clam shell gate — a section of a cylinder on arms that swings aside, like a crane’s grab. They tend to leak, but with the material’s weight against the hinge pin, they are easier to close with a high force against them.
The upward bell gate, helps with in-bin flow pattern and seals well. Open by pulling from above or pushing from below, through the outlet. The material moving around the gate acts to improve the flow, and because the material at the lip is on an inclined surface, they tend to seal better. If it still has a leakage problem, a flexible lip can cure it.
A cone, suspended on a cable below the outlet of the hopper is a downward bell. Lowering the cable lets material flow between the outlet rim and the bell. When the cable is raised, if a lump sticks at one place the bell moves aside. The sealing surfaces are angles, so material rolls off. The bin is shallower and there’s no outlet pipe. This design ensures clearance so large particles don’t wedge against the wall as the bell closes.
Upward Bell, Downward Bell, Double Bell
Any of these gates would close just fine if not for the material in the bin. Double gates exploit this. The main bin has a normal gate and outlet. The outlet is below the lip of the much smaller, lower control bin. If the control bin fills, the main bin stops. The control bin has a gate larger than the main bin. Closing the main gate as far as it will go reduces flow through the control gate to a trickle. The control gate can now be fully closed, which fills the control bin and blocks the main outlet.
You might not want to share environments between bins. Maybe one has pressure, nasty chemicals, or hot gases. In that case, a rotary airlock gate is a paddle wheel apparatus in a close fitting housing. Material is metered out as it turns. A double gate also works (blast furnaces use double bells). If you need to meter a set amount, a sliding cavity like a grocery store bulk bin works. So does a rotary airlock.
Locomotive sander systems spread sand on the rails to increase traction. The sand is gated with a “sand trap”. A pipe supplies sand to a ‘valve’ with a sharp upward U bend. Of course this blocks. A compressed air line from a valve in the cab feeds into the upward end of the U bend. As long as air flows, the blockage is constantly cleared and sand flows. It’s collected and sent to the wheels.
Feeders
If you need a constant flow, independent of how much is in the bin, you need a feeder.
The rotary air lock can be a simple feeder. A conveyor feeder is a belt at the bottom of the bin. One side has a slight gap between bin and belt. Material covers the belt as high as the gap. A screw feeder is a helical screw at the bottom of the hopper, taking material off to the side. The screw needs a varying pitch, starting out slow and increasing, to let it fill gradually from all along the hopper. A vibratory feeder is a chute designed to arch, with a vibrator to make it flow anyway.
Any of these can have a poor pattern of feeding, taking from one place along it’s inlet. Fins and inserts in the bin can help – a doctor blade to regulate how deep the first couple inches of belt feed, or an anti-rathole type insert to keep mass flow going.
Conveyors
Unlike a feeder, a conveyor depends on whatever is feeding it to control the feed rate. Feeders are for controlling feed rate. Conveyors for moving stuff. A feeder will change it’s output when it’s speed changes. A conveyor may change how much is in each section (the ‘loading’) but the output is speed independent.
Screw conveyors should have a fixed pitch, and can be angled up to 45 degrees. Belts can be inclined up to the angle of repose of the material. These are best made with a slight ‘V’ in the belt so the material doesn’t roll off. Boards on the side also work, but introduce friction into the system as the material slides against them.
Don’t overlook skips — a bucket pulled up an incline. The front wheels run on tracks slightly narrower than the back wheels. Dip the inside tracks down at the end to dump.
Moving floors made of long strips will move a pile of material if actuated in the proper sequence. Picture the order as ‘123123123123’: shove 1 backwards suddenly, and the material above it will stay with the mass, do 2 and 3, then slowly move all forward. They also move solid objects, so many trucks have such floors.
Finally, you can always fluidize the material and blow it about with air or water, then remove the fluid at the other end. Think old time logging, with logs floated down the river.
Have fun hacking. We hope we’ve given you some options for dealing with walnuts.
What exactly qualifies as comfort food is very much in the palate of the comfortee. Grilled cheese may not work for everyone under every circumstance, but we’ll risk a bet that the gooey delicacy is pretty close to universal, especially when you’re under the weather.
But if you’re too sick to grill up your own and don’t have anyone to do it for you, this grilled cheese sandwich-making robot might be the perfect kitchen accessory. Dubbed “The Cheeseborg” and built as a semester project by [Taylor Tabb], [Mitchell Riek], and [Evan Hill] at Carnegie-Mellon University, the bot takes a few shortcuts that might rankle the grilled cheese purist. Chief among these is the use of a sandwich press rather than a plain griddle. We understand that this greatly simplifies the flipping problem, but to us the flipping, especially the final high arcing double backflip onto the sandwich plate, is all part of the experience. Yes, a fair number of sandwiches end up going to the dog that way, but that’s beside the point.
As realized, Cheeseborg feeds bread and cheese from stacks using a vacuum arm, sprays the grill with butter, and uses a motorized arm to push the uncooked sandwich into the press. At the peak of grilled perfection, the press opens and ejects the sandwich to a waiting plate. As an added bonus, the whole thing is Google Assistant enabled so you can beseech Cheeseborg to fix you a sandwich from your sick bed. See it in action below.
Pick a card, any card. [Andrew Quitmeyer] and [Madeline Schwartzman] make sure that any card you pick will match their NYC art installation. “Replantment” is an interactive art installation which invites guests to view full-size leaf molds casts from around the world.
A receipt file with leaf images is kept out of range in this art installation. When a viewer selects one, and carries it to the viewing area, an RFID reader tells an Arduino which tag has been detected. Solid-state relays control two recycled clothing conveyors draped with clear curtains. The simple units used to be back-and-forth control but through dead-reckoning, they can present any leaf mold cast front-and-center.
Clothing conveyors from the last century weren’t this smart before, and it begs the question about inventory automation in small businesses or businesses with limited space.
[gwfong] was in a bind. He had to make a unique Halloween prop that dispensed candy to young trick-or-treaters at a Haunted House. He decided on a conveyor belt system and besides being functional, it also had to be inexpensive to make. After poking around the hardware store [gwfong] had an idea: make it out of items he can re-use after Halloween!
As you can see, the main roller system is made of paint rollers. These are cheap and certainly re-useable after the conveyor is disassembled. Luckily for the project, the handle of the paint roller just happens to fit very snugly into a 3/4″ PVC pipe fitting. Four T-fittings and some short lengths of PVC pipe were purchased and are used to mount the paint rollers to a wooden base. A piece of canvas cut to length and sewed into a continuous loop makes up the conveyor belt. A loose belt certainly won’t deliver any candy so two turnbuckles, one at each end, keep the belt tight on the rollers.
There is a DC motor that spins a pulley which is coupled, via a standard rubber band, to one of the end paint rollers. A full-speed conveyor haphazardly flinging candy around wouldn’t work out to well so an Arduino and motor shield are used to control the conveyor’s speed and duration. A 7.4 5000mAh Li-Po battery provides the necessary electricity for a nights-worth of un-tethered candy dispensing.
Looking at this 17-stage Great Ball Contraption makes us think that [Skiyuky] should be working in industrial automation. The build, which has been assembled from an untold volume of LEGO parts, moves a reservoir of round plastic balls around a circuit. Each module exhibits a different mechanical way of handling the parts. It’s certainly not the first GBC we’ve seen, but the previous offering combined stages from many different makers. [Skiyuky] built this one all himself over the last two years.
The video after the break starts off at the main depository of tiny soccer and basketballs. To help illustrate how long it takes to move around the entire circuit [Skiyuky] adds a red and blue ball which are both easy to spot. From there it’s a Willy Wonky type of ride through all manner of contraptions. We’re struck by accuracy and efficiency with which all of the stages operate.
The blurry image above is a snap of toy cars as they zoom around a multi-lane, multi-level, maniacal-maze called Metropolis II. We originally took a look at the video after the break (do it now!) but found more information on [Chris Burden’s] kenetic sculpture in this NYT article. He and eight studio artists began work on the project back in 2006. They built 1200 custom designed cars and gave them a huge city to traverse, with up to 18 lanes at times. The work is not yet done, and the video below is dated (having been filmed in 2009), but project is slated to conclude in about two months and the installation has already been snapped up by the Los Angeles County Museum of Art.
And here we thought this was the product of an out-of-work packaging system design engineer. Nope, it’s art, and it certainly eclipses other kinetic sculptures we’ve seen.
This build started with an off-the-shelf chocolate fountain for which [Chaz] designed and printed a new nozzle in PLA. He also knocked off the flutes that make it fountain on the band saw and removed the rest of the material on the lathe.
