DnD Table 3 and 4

Preamble

Our gaming table has gone through many phases.  The first was an 8x4 foot sheet of plywood on some sawhorses.  We wrapped it in felt and stapled it down, but the felt kept pilling and it was hard to replace.  We chopped it down to 6 feet, split it down the middle and swapped vinyl for felt, but the legs were still hard to store.  The third mod was to replace the cumbersome legs.  The fourth was a new and lighter table top.

This has been useful for gaming, crafts and many other activities.  It is light weight and takes up very little room.  We keep ours in the garage and pull it out when we need it.

The Legs

Lowe's had some really nice seasoned 2x3's.  A few hours and chop saw got me a new set of legs.  The chief features of the table are its simple construction and plentiful leg room.  It has been a chore to find a good way to attach the top to there, however.  Overall, the legs have been maintenance and trouble free.  If I borrowed the design from somewhere, I have forgotten it.  If you attempt to replicate it, read all instructions first, measure twice and cut once, and always wear your safety glasses.

The cut list is basic and can be created from six 8 foot 2x3's, Not compound angles are needed, but the legs have angled cuts.  The measurements below rely on the geometry of your lumber being moderately predictable: Two 2x3's together should come out to 3 inches.  You may have to adjust the length of your interior cuts if this is not the case:

• Outside Length: 72" x 2
• Inside Length: 69" x 2
• Outside Width: 27" x 2
• Inside Width: 21" x 2
• Legs: 30"+ x 4
• Blocks: 4 1/2" x 2 1/2" x 4 (mine are from oak as that's what I had lying around)
• Lots of 2 1/2" construction screws
• 4x 5 1/2" Carriage Bolts with Washers and Nuts

Assembly of the top is also basic.  Remember to drill pilot holes for all screws ans work from the inside out:

1. Inside Width -> Inside Length 
2. Inside Length -> Outside Width
3. Outside Width -> Outside Length

The legs can be tricky to position depending how high you want the table top.  For my 24" height top, the legs are 26 1/2" with a 75 degree cuts at both ends (making a parallelogram and not a trapezoid).  The legs meet in the center of the table top.  The math to place the hole precisely has been lost, but those inclined should have no trouble replicating it.  In general, slip your uncut legs into the slots between the Inside and Outside Length so that they meet in the middle.  At a point between 9 and 11.5 inches from the end of the table end, drill the hole for your carriage bolt through both Inside Length, the Leg and Outside Length.  Make sure the hole is not closer than 2 3/4" from the end of the Leg.  Thread the bolt through the hole and test your leg height.  Cut your leg into a parallelogram to maximize contact with the floor and minimize interference with the table top.  Position the Blocks to ensure the legs only rotate a certain amount.

If all goes well, you should have a sturdy and light set of legs to use as a base for any table top you can dream of.  The method of attaching the top to the base is discussed in the next section.

The Top

The latest addition was a lighter table top.  Previously, we used a piece of 3/4" Oak Plywood with vinyl stapled to it.  This was extremely sturdy and stable, but it was a huge pain to move.  I designed the new top to be light and attach directly to the legs.

Much like the legs, the top was stick framed using flashing from Lowe's.  This time, 1x2's provided a good base, and Kreg Pocket Hole joinery held everything together.  Along the center line, two lengths are abuttewd to provide enough surface area for the hinges.  Instead of heavy plywood, I used a thin luan top.  All this was wrapped in vinyl again (the most successful table covering we've had thus far).  Unlike previous folding incarnations, the vinyl was split in two pieces and each half of the hinged top was wrapped separately.  The cut list for my 6' 6" top is below.  The Inside Stiles are not required to be the listed lengths as long as their total lengths come under 72".  I placed them so they would fit between the blocks in the legs and help the top align to the legs.  Your mileage may vary; see lessons learned below.  As always, your local dimensional lumber may vary, measure twice, cut once, and always wear your safety glasses:

• Outside Stile: 78" x 4
• Rail: 19" x 8
• Inside Stile (Ends): 17 7/16 x 8
• Inside Stile (Center): 37 1/8" x 2

Assembly is a little trickier than the Legs.  With your pocket hole jig, join the Outside Stile to the Rails at both ends.  Use the Inside Stiles to locate where to place the inside Rail.  Add the Inside Stiles to make a double-layer of wood in the center of the table-top to better brace the hinges.

With two halves of a table top in hand, it is time to locate the hinges.  Match the hinge location to your legs so they won't interfere with how the table sits flush.  The vinyl wrapped on the side that will be the center of the table will need to be relieved where the hinges will go.  I chose to wrap after attaching the hinges.  I now feel this was a mistake. In the pic above, I've routed out a place for my hinges.  In practice, I didn't need to do this.  Just clamp the table halves together after the vinyl is in place, locate your hinges parallel and centered on the joint and screw in place.

I have tried many things to secure the table top with a minimum of fuss.  Right now, I'm using machine screws and associated sockets sunk into the top.  The screws thread through the legs and into the top.  They require climbing under the table.

Lessons Learned

1. I would decide on a method of attaching the table before I started building.  The primary candidate is a Sash Lock.  Placed correctly, it would easily lock the legs to the table top without climbing under each time.
2. I would avoid insetting the hinges.  Instead, careful placement would allow the hinges to be used without interfering with the mating of table top and legs.
3. I would wrap the vinyl completely around the top so all stapling was done on the bottom.
4. I would not tell my gaming group how much better this version of the table was until after it had proven itself.  I have gotten no end of grief every time I climb under it to hook the two together.  What are friends for, eh?

Bonus Shot: Plans

Updated: Random Shop Projects

Cat Tower

We needed a new cat tower due to acquiring a monster of a tom.  Might as well do it right!.  I wrapped the columns in sisal (one roll of Lowe's Blue Hawk lasted about a foot and a half), made the base double-thick plywood, and wrapped all horizontal surfaces in carpet.  There are a brazillion staples in that thing.

I wish I had purchased round posts instead of these ungainly square ones.  Not only were they more difficult to wrap, but the sisal seems to pull away and tear easier when it sits a quarter inch from the surface in the middle of each face.  The next model will have pillars, and I have half a mind to glue the sisal in place to lengthen the time it takes to get into such disrepair.

Update: I made a small tower for upstairs and glued the sisal in place.  It seems to be holding up much better over time.  Instead of using square pylons, I used redwood ties from Lawn and Garden.  They wrapped much nicer than the square ones.  It is held by a single bolt and, as of this writing, has broken once when someone fell on it.  Eep!

Vacuum Tool Holder

This serviceable Shop Vac tool holder plan came in via Shop Notes.  The tools are sitting atop PVC end caps of a fitting size.  It took longer to find the parts than it did to assemble the thing.

Miter Sled

Shop Notes, Woodworking for Mere Mortals and a bunch of Indian Rosewood acted as a catalyst to get me to build a Miter Sled.  I hate miters on a contractor's chop saw.  The constant adjustment leads to endless headaches.  The sled eliminates this with a stable 90 degree platform that facilitates perfect cuts every time.

The base is plywood, and I followed the techniques of the above YouTube video to get my rails aligned.  To each arm, I added T-Track and will build stop blocks.  These will be invaluable for building boxes and lots of picture frames in the same size. 

Now all I need is a spline jig that stands the miter on end and allows reinforcing slots to be added...

Bonus Shots

Miter Sled Plans

Garage Shelves Plans

Bitz Wall for Blue Table Painting 

Page 2

OFBC: Design and First Prototype

Note: This is part of the Project Write-up for OFBC: One Fluorescent Beer Coaster

Circuit Design

I began the search for parts to fit the Instructable, and I realized I had a lot to learn about each part.  To match the circuit, we searched Frys, Radio Shack, ebay, Mouser and many others online. For an unproven design, going with an unknown module and supplier wasn't an option. Instead, we found all the components we needed on Adafruit.

• Lithium Ion batteries must be matched to their charger to avoid dangerous heat and combustion incidents.  Capacity is determined by the Amp-hours rating.  The LEDs I was targeting were a max of 350mAh, so I looked for batteries had to be over 1000mAh to get the targeted 3 hour run time.
• The charger choice was mostly driven by battery choice.  We didn't feel like we could provide a mounted Micro-B port in the time available, but a charging circuit mounted to a full sized USB plug was a good substitute.  With the shell, we would provide an easily removable bottom and 'mouse hole' to allow the charger to live outside the case.
• Most LED projects online mention heat at one point or another.  To get ahead of this concern, we opted for a heat sink-mounted super bright LED.  This same LED bead was seen on ebay without a heat sink, but we didn't want to screw anything up due to inexperience and opted for the more expensive package for the first run.
• The Driving Circuit was a simple buy, and the choice also dictated our resistor purchase.  The key value from the MOSFET we purchased was Gate Threshold Voltage.  The voltage drop across R2 with the battery we bought had to match this value.  Using V = IR, R = V/I = 1.5V / 350mAh ~ 4 ohms.

Materials List

Name	Description	PID
Battery	Lithium Ion Polymer Battery - 3.7v 1200mAh	258
Charger	Adafruit Micro Lipo - USB LiIon/LiPoly charger - v1	1304
LED	1 Watt Cool White LED - Heatsink Mounted	518
Driving Circuit	N-channel power MOSFET - 30V / 60A and NPN Bipolar Transistors (PN2222) - 10 pack	355 and 756
Resistors	100K and 3.5 Ohm Resistors	Already Owned

Components, Breadboards and Protoboards, Oh My!

Once the materials were in hand, the breadboard went well.  It worked the first time!  While we waited for batteries to charge, we used a simple brick of 4xAA batteries.  The beauty of the driver we chose is that it can drive LEDs using any voltage source over the target voltage.

Using the breadboard and schematic, we attempted a protoboard version of the circuit.  This was a complete mess, and it took us a lot longer than it should have.  However, by the end of a single prototyping session, we turned a jumble of components into a working light.  One high/low note happened when we wanted to minimize the number of connections but didn't have the right resistor for R2.  We twisted two resistors together to get close to R2's 3.5 Ohms and put them through the same hole on the protoboard.  Instant parallel resistor!

Conveniently, the whole project fit under a Ziploc Container lid.  A little bit of hot glue, another section of protoboard with a hole in the middle, and charged batteries got us our first complete prototype!  It was brighter than the equivalent cell phone flash and had excellent diffusion through some purpose-bought Smirnoff Ice.

Touchscreen on Raspberry Pi

A friend has a few Elo Touchscreens from a past venture, and I have racked my brain trying to figure out a use for them. After giving up on Android PCs, I took a stab with a Raspberry Pi Model B running the Raspbian image from Noobs.  Two obstacles presented themselves:

1. The Raspberry Pi only outputs HDMI.  For now, I'm going to try an HDMI to VGA converter. Better to get this thing off the ground than hem and haw about a 'better' solution.
2. The touchscreen is inverted.  For this, I installed the xinput-calibrator tool per the instructions on the Raspberry Pi forums given by msmithy12 and a helpful config guide:

sudo apt-get install libx11-dev
sudo apt-get install libxext-dev
sudo apt-get install libxi-dev
sudo apt-get install x11proto-input-dev

download http://github.com/downloads/tias/xinput_calibrator/xinput_calibrator-0.7.5.tar.gz 

tar xvzf (downloaded file)
cd (downloaded file)
./configure
make
sudo make install

Then, from the menu: Preferences/Calibrate Touchscreen

3.  Do not immediately follow the instructions given when you run calibration (place the calibration in a /etc/Xll/...).  Doing so borked my Raspbian install.  Instead, create the file specified in /usr/share/X11/xorg.conf.d/.  I ran "sudo leafpad 99-calibration.conf" to create and edit the file.  After dropping in the calibration indicated, I restarted and found out it stuck.  Woo hoo!

 I will update this space with my progress.  Currently, the setup is:

• Raspberry Pi Model B ($35)
• Elo Touchscreen ET1939L (Pre-owned)
• BYTECC HM-VGA005 HDMI-A to VGA Female Adapter/Converter ($20)
• 1 x WiFi Dongle (Ralink RT5370 chipset) ($10)

Lessons Learned

• Single User Mode could have beenused to save my Raspbian install.  It can be entered by adding init=/bin/sh to cmdline.txt.  I was using Noobs, so holding Shift while the PI boots got me into the editor.
• I like Linux more and more each project.

OFBC: Inspiration and Research

Note: This is part of the Project Write-up for OFBC: One Fluorescent Beer Coaster

The Idea

As night descended at Toxic Barbecue at DEF CON 21, everyone was working through the meat and alcohol they'd consumed much too fast and in much too large a quantity.  Rather than move the party somewhere else (Las Vegas' Sunset Park is safe at night, right?), we began to experiment with cell phone screens, then their flashes.  The lights were bright, but they were also extremely narrow in focus.  

The Liter of Light project gave us an idea to use a liquid to diffuse the light.  As there was still copious amounts of alcohol left behind, we started experimenting.  This 'research' lead us to decide that Smirnoff Ice was the best diffuser.  Filtered beers were awful due to both the dark bottles absorbing light as well as the liquid having no solids to scatter any that was left. Smirnoff had the clear bottle and label as well as a ton of solids from the included fruit juice.  As this was a hacker party and not for frat boys, we had plenty left. The misogynists among us named them 'Bitch Lights' after the colloquial term for Smirnoff Ice: Bitch Drinks.  We had our product; now we needed to separate it from the phones.

Research

DEF CON 22 planning made us realize that we needed to make good on our promises made while too intoxicated to realize we knew nothing about how LEDs actually work.  First stop?  The local Hackerspace, of course.  SYN Shop is in downtown Las Vegas.  Multiple forum members are lighting and electronics techs on The Strip.  They pointed me towards specific packages, drivers and batteries.  I took this foundation and boiled it down to specifics.  I wanted the light to be composed of the following elements:

1. Super Bright LED (1W, 100 lumens)
2. LED driving circuit
3. Battery (3-4 hours of time)
4. Charging circuit (USB)
5. Switch to turn it on
6. 3D Printed Body

Armed with search terms from the forum, I found a wealth of helpful links.  I found LED packages that fit the "Super Bright" definition all over the web.  I learned a ton about batteries and chargers (did you know Sears still exists and has an online store?).  The most helpful site was Instructables.  There, I found several LED driver circuits that I actually understood.  After a trip to Frys left me bewildered with options, I learned to better read datasheets.  Finally, I had a working circuit design.

Flames of War - SS Army Pics

This weekend, I returned briefly to the world of miniature war gaming.  My father is putting up his Flames of War army for sale locally.  He's a history buff, and I learned a lot about the German WWII army composition by helping him catalog these.  I built some of these pieces, but mostly I just took the pics.  No detail shots, unfortunately.

Artillery

I love the frozen ground effect on these bases

Misc Infantry

Misc Command 

Heavy Machine Guns 

 Mortar Half Tracks

Tanks

 Panthers

Reconnaissance Car/Tanks 

PIVHs with Skirts 

Tigers

Mechanized Infantry

 Platoon 1

Platoon 2 

Platoon Command 

R2B2

I built a copy of Justin Engler's Delta Bot R2B2.  Here's how I did it with a revised parts list.

Inspiration

Justin Engler and his iSEC Partners team presented his PIN punching robot at DEF CON 21.  Even though it was, by his own admission, a last resort in cracking phone PINs, it received coverage in Forbes and other outlets. 

Build

The 3D prints from my brother's Replicator came out well.  The dimensions were correct overall, but I had to do some filing to get the mounting bracket to slot together.  The servos I used required me to file out the slots a bit as well.  The spokes from my servo mount were a little large, so I filed those down too.  Overall, it wasn't too tough to fit everything together.  When I build another one, I need to see if my problems were caused by the STL files, how the G-Code was generated or the calibration of the printer itself.

The local RC shop called Hobby People had most of the small and moving parts.  Servos, ball joints and such came in at under $30.  Lowe's had the right sized all-thread to finish the job.  One thing about the construction was that I originally bought 10mm hex cap screws to join the ball joints to the biceps.  The way the bicep is built, though, the joint tends to hit the side of the bicep and limit the range of the effector.  To solve this, I moved the ball joints outward with small washers.  This made the 10mm hex caps too short, so I went with 15's instead.  Redesigning the bicep to free up movement might resolve this problem.  I slipped a metal stylus pen through a rubber grommet and effector.  The stylus was grounded with an alligator clip onto the breadboard.

The rest of the robot (as you can see in the pic) are an Arduino Uno, a small breadboard and a four-legged stand I put together from a 1x2 and some angle braces.  The robot is held to the frame by a fender washer through the central hole of the mounting bracket.  The sketch had to be modified with the correct measurements on the actual robot.  Most everything matched, so that built my confidence.  Once I uploaded the sketch, I played around with the machine code and made it dance.  This is when I found out the ball joints were binding against the bicep.  I also dropped the robot, and the short hex caps made it go eveywhere.  D'oh!

I forked and cloned Justin's github to prep for writing some code and tidying up the notes.  Rather than cracking phone PINs, I plan to use this to punch card PINs on PIN Pads used in credit card processing.  I don't think I'll need the OpenCV code, so I'll have a blind version of R2B2 up in my own repository once I learn enough Python to be dangerous.

Finally, Marginally Clever has a new version of the delta bot that uses laser cut parts.  The R2B2 that Justin demoed at SXSW seems to have been made from this version out of acrylic.  Snazzy!  This comes with its own platen and looks mighty sturdy.  I might have to grab one and give it a spin.

New parts list

Count	Cost Each	Name	Description
2	$1.94	Du-Bro 2123 3.0 mm x 10mm Socket Head Cap Screw (4-Pack) P/N 2123	Screws to connect effector to ball joints
2	$1.94	Du-Bro 2124 3.0 mm x 15mm Socket Head Cap Screw (4-Pack) P/N 2124	Screws to connect bicep to ball joints
2	$1.98	Traxxas 5347 Rod Ends with Hollow Balls Large Revo (12)	Ball joints to form the arms from threaded rod
6	$1.04	The Hillman Group 44817 8-32 x 6-Inch Threaded Rod, 10-Pack	Threaded rod for ball joints to connect bicep to effector.
3	$7.99	The Hillman Group 44817 8-32 x 6-Inch Threaded Rod, 10-Pack	Servos that connect to bice. Most will work, but Hobby People has adequate ones for cheap
As needed	Varies	Washers,Flat,3mm DUB2109 and The Hillman Group 36-Count #6 x 3/8-in Zinc Plated Standard (SAE) Flat Washer	Washers to separate arm from bicep and effector. Used to give arms maximum freedom.
1	$2.00	Like Hillman Rubber Grommet (5/16x5/8x5/8x7/16)	Rubber grommet for effector to hold stylus
1	$4.00	Like Stylus pen	Stylus for effector
1	$1.13	1 x 2 x 8 Spruce-Pine Furring Strip	Body for robot
1	$1.13	1-in Zinc Corner Braces	Braces to hold shape of robot
X	$2	Bolt, fender washers and wingnut	Bolt to hold robot to body