Introduction: Build a Mobile Bar - BaR2D2
Runner Up in the
Craftsman Workshop of the Future Contest
The concept for BaR2D2 was born when a friend showed up to an event with a radio-controlled cooler. We joked about taking the idea to the next level and in the Spring of 2008, construction began.
If you enjoy BaR2D2 as much as we have, be sure to rate this Instructable a 5 and vote for it in The Craftsman Workshop of the Future Contest!
Just a quick note about me - I am a regular DIY'r and don't have any formal robotics, electronics, or mechanical training. I have picked up most of my skills from various hobbies and projects, as well as my father who is a skilled woodworker. If you have a basic knowledge of woodworking and working with low voltage power, then you can build a mobile bar! Enjoy!
Step 1: Creating the Framework
As far as tooling for this project, here is a pretty good idea of what you'll need:
Heat gun (hairdryer will work)
First, purchase a sheet of 4ft x 8ft x 3/4 inch plywood. I used the flooring grade as it will be covered later.
Cut the sheet into 8 2ft x 2ft squares and mark their center points by drawing an X across the middle from the corners. Drill a 1/4 inch hole in the middle of them.
Using a router table, measure out 9 inches from the edge of the cutting bit and bolt your wood square loosely to it. Turn the router on and plunge it slowly upwards until it goes through the wood. Lock the router in place and proceed to rotate the squares until you complete the circle. Repeat eight times. This will give you 18 inch circles. Why 18 inches? I am using an off-the-shelf plastic dome that is that size. Specifically, it is a clear dome from Aspects used for bird feeders. This was purchased from a bird store for $35. The shot dispenser we are using is available on ebay new for $30.
Three of the circles will be cut into rings. To cut out the centers, I made a quick jig as pictured to be able to rotate the circles against it. Two of the finished rings should be 1.75 inches thick and one will be 1 inch thick.
Take one of the circles and setup the router to create a groove about 3/4 through the thickness for the dome to sit in.
Step 2: Creating the Vertical Stringers and Grooves
Next, I ripped the vertical stringers from poplar on the tablesaw. You will end up with six pieces that are 1 inch x 3/4 inch x 43 inches.
You will need a dado saw blade for the next steps. This tool allows you to stack blades and spacers to cut nice, clean grooves.
Cutting 3/4 inch grooves in the poplar vertical stringers and circles will make the bar fit together like a puzzle when assembled. Cut grooves at the end, then at ten inches down, then 20 inches, then 32 inches, and finally, the other end.
To cut the grooves in the circles, I stacked them, put a bolt in the middle to hold them together, then clamped them between two blocks and ran them through the dado blade as pictured. The six uprights will be spaced equally all the way around. Note - Take note of the pictures in the other steps as some of the pieces will get cut away to allow for the drawer.
Step 3: Assembling the Main Structure
Next, we will assemble our notched pieces with glue and screws. Use a hand drill to bore pilot holes in the pieces. Use a countersink bit on the vertical pieces to make the screws sit flush. Note - do not install the top ring for the dome yet as it gets installed later.
As you can see in the pics, we used three of the vertical stringers to go the full length of the robot. The other three, we cut off and attached them from the table level to the bottom. Use a square to make sure everything is straight.
Note - You will have two rings left over at this point.
The neon in the pics is for fitting purposes at this point.
Step 4: Priming and Coating
Use wood filler to fill any voids or grain irregularities and sand the structure until it is smooth. Use a spray primer and sand/fill as needed.
The structure is now ready for coating. I used a black spray-on truck bed liner product. It will take six or more cans to get a good coat. This works best if your surface is sealed and smooth.
In the pics, you can see the test fit of the shot dispenser and neon rings.
Step 5: Building the Drivetrain
I searched high and low for a good, reliable drivetrain solution and settled on an electric wheelchair due to the reliability. I combed Craigslist and scored a used one for $75. (these things cost upward of $1,000 if new!)
Strip the chair to its frame as it will most likely need to be repainted or thoroughly cleaned. My chair had an extra set of wheels out front that I stripped for aesthetic reasons. Make sure you keep all the wiring harnesses as we will reuse those! Plan on buying a new battery if the chair has been sitting. (these run about $75) I purchased a 12 volt, 35 amp hour battery which is sufficient.
Once stripped, the frame needs to be degreased. I stripped and repainted the wheel rims at this point as well.
You will need three solid points to mount the main structure of the robot to the base. I used some parts off the discarded frame and had them welded to the front to make two of the mount points. You can see three 1/4 inch holes in the frame where the top of the bot will mount. At this point, test fit the battery and add any mounts or tiedowns necessary to keep it from moving around.
Once you have the frame reconfigured, repaint with a black semigloss spray. I used Krylon. The wheel covers on the back were also sprayed with the bedliner.
When dry, reassemble the frame and set aside.
Note - don't worry about trying to make the frame lighter. Any additional weight on the bottom only makes the robot more stable when moving.
Step 6: Constructing the Drawer
The motorized ice/mixer drawer goes in the bottom section of the robot keeping the center of gravity lower to the ground.
Purchase a set of 14 inch drawer slides and mount them to wood strips as pictured. We then use some 3/4 inch plywood to make a base that slides in and out. The drawer will be attached to that.
Use one of the rings we had set aside and cut two identical pieces from it to create the curved front of the drawer (20.5 inches of diameter) Use some of the vertical stringer scrap to make the vertical pieces. (face is 8.5 inches tall) Once the drawer face is done, use paper to create a template for the drawer bottom and cut that from 1/4 inch plywood. The sides and spacers can then be added. For the ice bin, I found a blue translucent one with a handle at the dollar store. It needs to be translucent for the light to illuminate the ice. The drawer body without the face is 14.5 inches wide.
Note - Continuously test fit the drawer. Spacer blocks were used to shim the drawer front to proper alignment level. The front will be sheeted with blue Sintra plastic in a later step.
To motorize the drawer, I purchased a 12 volt DC gear motor from a surplus store. 15 rpms gives the drawer a perfect speed when attached to a three-inch traction wheel. This wheel rides on the inside floor of the robot. I used screws and small springs to mount the motor. This allows you to adjust the tension and traction.
To control the elevator via the remote, I visited Team Delta and purchased a RCE220 rc switch. This allows the motor to operate in both directions, stop at limit switches, and be controlled from one button on the remote. Follow the instructions that came with the RCE220 to wire it.
I insulated the area below the ice bin with foil back bubble material. Simply make a paper template and then use that to cut the insulation. Use spray adhesive to attach it to the drawer.
To illuminate the ice, I installed two LED light pucks. I found a three-pack of these at the local drugstore.
The drawer gets trimmed a little later.
Step 7: Making the Beer Elevator
The level above the mixer drawer houses the beer section. Beers rotate on a beer turntable and then an elevator brings them to the table level.
Since there wasn't a "beer elevator" at the store, I had to invent one. I bought a cordless caulk gun from Harbor Freight ($40) and disassembled it. This is basically a linear actuator that is extremely compact. This is run at 12 volts.
To control the elevator via the remote, I visited Team Delta and purchased a RCE220 rc switch. This allows the motor to operate in both directions, stop at limit switches, and be controlled from one button on the remote. Follow the instructions that came with the RCE220 to wire the elevator.
Using a hole saw, I drilled a 3.5 inch hole in the table top. This needs to be positioned so that the edge of the hole is just inside the ring on the table top. Directly under that hole, drill a 1.5 inch hole in the floor of the beer section. Using wood screws, mount the elevator to the underside of the beer level.
Step 8: Building the Beer Turntable
3/4 inch plywood is used for the base. Cut a square about 2 foot square and cut and contact cement a piece of white 1/8 inch Sintra plastic to the top of it. Sintra is a brand name of expanded pvc sheet. This comes in 4 x 8 sheets in almost any color you could want and is usually about $30/sheet from any plastic supplier.
Using the earlier router table setup, mount the piece and cut it into a 16 inch circle.
Next, cut two pieces of the Sintra about 18 inches and center mount them together. Draw your beer layout as shown below. Temporarily attach a paper template (my friend drew it in Illustrator) to the pieces and start drilling the large holes using a circle cutting bit on the drill press. Once you have the 15 holes drilled, you will mount the pieces on the router table and spin them to remove the unneeded parts. This will leave you with two beer guides. I later went back and drilled some holes for the sake of looks. I also drilled five equally spaced 1/4 inch holes that mount the pieces to the base.
For the base, I used the template to drill a hole about 1.5 inches around where each beer will sit. This allows the elevator to come up through the hole, but will not allow the beer to fall through it. I cut out the extra material between the hole and the edge with a table saw to allow extra clearance for the elevator.
The base also gets five holes for bolting the two beer guides to it. Use five 1/4 inch bolts about 5 inches long. These need to be countersunk under the base to allow it to spin. I centered and mounted a 6 inch lazy susan bearing (Home Depot) to the bottom of it.
To drive the turntable, I used one of the 12 volt, 15 rpm gear motors I earlier purchased from ebay. I used 2 inch x 2 inch steel angle to make a simple motor mount. I used a hole saw to cutout a 3 inch circle (wheel) that I epoxied to the motor shaft. Grip tape was applied for the outer tread. The motor was mounted under the floor of this level so that the wheel was allowed to protrude through a slot and contact the bottom of the turntable to rotate it.
A beer guardrail was also cut from 1/8 inch thick UHMW plastic. Mount this to the inside of the uprights to keep the beers snug.
Step 9: Creating the Mounting Plate for the Base
In the drivetrain step, we explained the need for three solid points to mount the robot body. This step explains how to make the male side. A plate was cut from 3/4 inch plywood at 45 degree angles on the tablesaw for a low profile (approximately 16 inches x 10 inches)
You will need to mark your three mount points from your drivetrain onto the plate and install 1/4 inch counter sunk bolts with nuts. The plate is then centered on the bottom of the robot body and attached with glue and screws from both sides for a solid mount.
We use split washers and wing nuts for quick assembly/disassembly. Holes were drilled to allow the wires for the battery and motors to pass through.
Step 10: Adding the Electronics
The electronics for the mobile bar are fairly simple using off-the-shelf items. The entire robot runs off a 12 volt, 35 amp-hour SLA battery. The radio controller/receiver is a six channel Futaba model tuned for ground frequency use. This was purchased from The Robot MarketPlace.
A pair of Victor 883 Speed Controllers is used to control the drive motors on BaR2D2 and are set up for "tank-style" steering. Note - for ease of driving, we set the transmitter up to use one stick to control the drive (mixing function). Follow the instructions included with the speed controllers for installation and setup. These were mounted on a piece of Sintra.
I reused the wiring harnesses and plugs from the wheelchair to provide wiring from the battery, to a main switch and to the motors. This allows you to easily unplug everything for transport. The switches and wire were purchased at Radio Shack.
At this point, limit switches were on the beer turntable. They are wired in conjunction with the beer elevator and beer loading door so that: A) Anytime the elevator is up, the turntable can't spin, B) When the elevator goes back down, the turntable is allowed to rotate until the next beer hits a limit switch, C) The turntable and elevator can't spin with the loading door open, D) A manual three-way switch allows for loading/off/dispensing of the beers. See diagram below. Zip-ties were used to secure the wiring.
Step 11: Installing the Plastic Skin
The mobile bar is sheeted in 1/8 inch Sintra. Sintra is an expanded PVC plastic that comes in a rainbow of colors from any plastic supplier (usually in 4 x 8 sheets). The Sintra cuts like butter on the table saw (use a high tooth count blade for best results).
The easiest way to make the pieces is to first make a template from thin cardboard then cut the plastic piece. Make them a little oversized so you can make fine fitting adjustments.
The plastic is quite flexible and springy so ratchet straps were used to keep the larger pieces in place while they were attached. Drill pilot holes and attach the pieces with #6 wood screws.
The clear plastic that covers the beer level is 1/16 inch polycarbonate (also available from any plastic supplier). This was attached using an air stapler. Make sure you use a scrap and test the stapling pressure before you move on to your actual piece.
The table top was made using the router table setup just like the earlier bulkheads. Mount it using contact cement.
Make any cutouts where access points are needed (speed controllers, drawer, etc.).
Step 12: Adding Chrome Trim
Adhesive backed chrome trim tape was used to finish the robot and give it some "bling." This comes in several thicknesses and colors from AutoZone.
Apply the trim per manufacturer instructions. A craft saw and miter block were used to make any angles that were needed. A Dremel tool also came in handy to fine sand some pieces.
A piece of plated gutter guard was used to cover the speed controllers then outlined with the chrome trim.
A chrome lid from an insulated travel mug was used to accent the opening of the beer dispenser (cut the center out of it and epoxy it on).
Center and mount the shot dispenser with wood screws. A template was drawn to aid in drilling equally spaced holes.
Step 13: Installing the Lighting
Two 15 inch neon rings were purchased from ebay. These come in many sizes and colors and are usually used for speaker installations. They operate via a 12 volt power transformer that has a built-in switch and sensitivity for pulsing to sound.
Mount the neon rings using the supplied hardware and instructions. Hide the wires using wire loom and run them through holes in the rings and serving level. Note - after mounting the lower neon ring, you would then attach the top wood ring to the structure and then mount the top neon ring.
The beers are illuminated by a camping light that has 60 white LED bulbs (ebay). This was attached with Velcro to the ceiling. For added brightness, a white Sintra circle was cut with the router and contact cemented to the ceiling of the beer area.
To enhance the lighting, a set of three blue LED pods (12 volt) were attached to the bottom of the robot body. These are commonly used to illuminate motorcycles and cast a soft blue glow under the robot. Note - these were not yet installed when the video was taken.
Step 14: Finishing Touches
A small ice scoop was purchased locally from a restaurant supply store.
A graphic designer buddy of mine drew up a great logo. This was taken to a sign shop that output/cut several logos in white adhesive-backed vinyl. Once applied, it looks like it rolled off a factory floor :)
We used some of the color inkjet iron-on transfers and made a few shirts to wear as well.
One item of note is the transport cradle. I used some 3/4 inch scrap plywood and traced an 18 inch circle on it and cut it in half. Three threaded rods and nuts from Home Depot were used to attach them together. Foam pipe insulation provides a soft cradle for the robot to lay on. This cradle was necessary to get the bot into my SUV for transport.
Step 15: Let's Party!
The radio-controlled portable bar (BaR2D2) made its debut at Dragon*con, the largest multi-media, popular culture convention focusing on science fiction and fantasy, gaming, comics, literature, art, music, and film in the US.
BaR2D2 was able to travel via street from hotel to hotel without issues. The large 12 volt, 35 amp-hour battery easily lasted eight hours before charging.
I welcome any specific questions about the construction if you would like help building a similar project.
As you can see from the pics below, BaR2D2 the mobile bar was quite a hit :)
If you think BaR2D2 qualifies as original and creative, then make sure you vote for this project in The Craftsman Workshop of the Future Contest.
Step 16: What's Next for BaR2D2?
As I write this, BaR2D2 is undergoing upgrades. The store bought shot dispenser will be removed. In its place will be six plastic bottles and a pressurized/regulated air system. A laptop computer with an extensive drink database will send commands to a Bluetooth receiver/circuit board on BaR2D2 which, in turn, will send them to six solenoid valves that dispense mixed drinks to order! The upgrade should be complete by Feb/Mar 2009.
BaR2D2 is scheduled to attend Dragon*con again this Labor Day weekend in Atlanta. If you see us, come check him out :)
Here is a pic of the upgrade parts template. Stay tuned for updates to BaR2D2!
Vote for BaR2D2 in The Craftsman Workshop of the Future Contest!
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