Tuesday, December 22, 2015

Backyard Climbing Wall

What Little Monkey doesn't want to climb?

When ours have more energy than can be safely confined within four walls, we always find it essential to have a selection of outdoor distractions.  After two trips to a local climbing gym, we decided that our own climbing wall would make a great new addition.

Fortunately, we had previously built a large play structure that was ensconced in a cushy layer of rubber bark.  One of its walls would be perfect for erecting a modest 10-foot wall for climbing and bouldering.

The first step was to assemble the materials.  Since the wall would be outside, this meant choosing materials that could weather the... well...weather.

I bought some pressure treated 2x4 beams from which to construct a frame, and two sheets of 3/4 pressure treated plywood to be used for the wall face.  The sheets needed to be prepped with deck wash prior to covering.  Fortunately, my helpers thought this was a fun task to do.
To anchor the holds, I created a template in scrap wood, and the Little Monkeys and I used it to mark out and drill mounting holes in the plywood, laying them out in a modified 8-inch grid pattern with every other row staggered sideways by half a column width.
To give it a nice grippy rock-like appearance, I bought a gallon of DeckOver textured deck coating in a dark gray color.  Since this stuff is normally used to repair damaged decks, I figured it would be perfect to both protect the wall and give it the durable surface for climbing.  The stuff is really neat and unbelievably thick.  It fills in cracks and crevices (enhancing the "rock" feel), and goes on more like drywall compound than ordinary paint.

200 Heavy Duty 4 Prong Zinc Plated 3/8" T-nuts (For 8' x 8' wall)Into the holes, we hammered in stainless steel T-nuts from the backside of the wall.  These would be used later to fasten holds to the wall with 2-inch stainless hex bolts.
Genuine climbing holds are easy to find on eBay.  I found a colorful assortment of 40 beginner-level "bolt-on" holds that fit the bill for about $70.  After mounting them to the wall, we were ready for some test climbing.
The Little Monkeys took to the wall right away... maybe a tad too quickly...

Part of the reason for making the wall was to give the Little Monkeys a place to get used to their climbing harnesses and practice repelling down after a climb.  So to make a top rope V anchor, I used 3/8" chain, bolts, wall hangars and locking carabiners, all in stainless steel.  

With that in place, they had their choice of bouldering and top rope climbing, and the wall was done.

Sunday, November 22, 2015

Steamer Trunk Coffee Table (with Stealth Cutting Laser)

What beats a plain coffee table? A coffee table made from a steamer trunk. What beats coffee table made from a steamer trunk? A coffee table made from a steamer trunk that hides a liquid-cooled cutting laser inside, of course.

In brainstorming ideas for a permanent laser cutter home, I got stuck on the idea of building it into a table.
Steamer trunk with a hidden surprise
I looked online for ideas and really liked the look and hidden storage of "steamer trunk" coffee tables. The laser cutter was already quite large, however, so I wanted the trunk that didn't have a lot of extra wasted space. None of the existing tables I found came even remotely close, though, so my only option (fortunately) was to construct one from scratch.

Cutting angle iron
Most steamer trunk coffee tables I found were built to resemble a classic steamer trunk resting on some sort of stand, perhaps with shelving below for magazines and such.

I decided to make mine out of plywood and steel and give it a distressed industrial look. I bought about 50 pounds of angle iron from Big Orange to make the frame. To cut the steel to length and miter the ends, I used a portable bandsaw from Harbor Freight that I'd mounted on a small stand.

Sadly, my existing welding skills were pretty sucky, so the next step would be tricky. The project required a lot of welding, so I'd have to step my game up to get it done. Fortunately, it also offered ample opportunity to practice. At the beginning, my welds were a brittle, lumpy mess. After a couple of false starts and more redos than I would have liked, I finally figured out that by carefully cleaning the metal beforehand and keeping the wand close to the surface, I could get a reasonably clean bead.

Full welded frame
Welded base
With that knowledge in hand, I welded together the table frame, creating both the trunk and a base unit that would hold a rack for sheet materials and the water supply.

Adding straps
After the frame was fully assembled, I sprayed it with rust-colored red primer followed by an oil rubbed bronze paint. When it dried, I lightly sanded the edges to give it a faux weathered appearance.

To complete a steamer trunk look, the frame included steel simulated "leather" straps, which I sprayed a contrasting copper color.

Caster wheels
To give the table mobility, I found some nice cast iron caster wheels on Amazon, and painted them the same copper color as the straps.

I didn't want the hard wheels to scratch the floor of my Man Cave, however, so I printed polyurethane rubber treads for them on my 3D printer using Ninjaflex flexible filament.

Corner hardware
From the Rocker woodworking store, I got some very nice streamer trunk hardware to make everything truly authentic, including corners, latches, and hinges.

They really sell the illusion. A light dusting in copper paint helped them blend in.

Staining wood
Distressing plywood
For side panels, I used hardwood plywood, and recuited Little Monkey and Littler Monkey to distress them before staining. Their eyes lit up when I gave them hammers and told them they could let loose with them.

I attached the paneling to the frame with button head cap screws to mimic the look of rivets. The hinges, handle, and corner hardware were fastened the same way. With the addition of some wire shelving on the bottom, and some access holes in the bottom, the table was complete, ready for its new occupant.

Hinging top to base

Installing laser cutter
I modified the laser cutter internally to route exhaust fumes to the bottom of the unit instead of the back, and also added some switched outlets so the fan and water pump could be enabled from the main control panel.

I inserted the laser cutter carefully, routing each water hose and power line through its corresponding hole in the trunk button. It was an incredibly close fit, with less than 1/4" clearance all around. In fact, I had to order a special right angle power plug to replace the one that came with the unit, and even had to shave that to make it fit.

Cutting name plate
Finished nameplate
As a final touch, I used the laser cutter itself engrave a nameplate for its home.

Completed table with Engraver
With the trunk top open, the laser is ready for action in all its blazing glory.

Assembled table
But with the top closed afterwards, all one sees is a handsome piece of furniture with nobody the wiser.

Sunday, November 8, 2015

Frickin' Laser Beams

3D printers are awesome!  I love using mine to repair widgets and toys, and make whatever random objects come to mind.  However, I've sometimes come to find the technology limiting.  First, it's not really great at making finished goods.  Also, the build materials are primarily constrained to a few types of plastic.   Finally -- and perhaps most importantly -- it could really use the added sexy appeal of a destructive frickin' laser beam.

Frickin' Laser Beam
Makerspaces are often equipped with laser cutters (aka laser engravers), providing an excellent compliment to 3D printers. Capable of cutting or engraving shapes and images into wood and plastic, and even etch images into glass, the results look completely professional, as they use the same process (if not the same machines) as commercial manufacturers.

For a hobbyist, I've always assumed that astronomical prices would keep the purchase of a laser cutter permanently unaffordable, or at least spousally indefensible.  In the last few years, however, a number of low cost Chinese laser cutters have come onto the market.  Instead of $3500-$15,000 or more, these bargain units have literally decimated the entry-level cost barriers to the technology.  And while the software can be awful and the hardware relatively crude when compared to their larger brethren, these laser cutters can be surprisingly functional and excellent platforms for hacking, modding, and upgrading.

Unboxing my K40
The king of these low cost laser cutters is the K40, a generic name for a family of similar devices assembled from different Chinese manufacturers using the same or similar parts.

I discovered them while investigating sub-$200 mini engravers -- compact devices built around the laser diodes used in DVD burner drives -- units capable only of slowly burning patterns into small wood objects such as keychains and cell phone cases.  In doing my research, I was surprised to find out that for only a little more money, I could purchase a full size unit built around a real laser.  Instead of a laser diode, a K40 uses a water-cooled 40-watt CO2 laser tube, and is capable of not only engraving, but cutting through 1/8" thick acrylic, cardboard or plywood.

Direct from China, one can get a bare-bones K40 on Alibaba for as little as $300, but I chose to pay only slightly more on eBay to get one from a US-based distributor.   It arrived a few weeks later, packed in an abundance of foam and cardboard.  It was larger than I expected, but I found it a temporary resting place on some ottomans in the Monkey Man Cave.  I'd work later to build it a unique permanent home, which I'll detail in a future post.

The laser cutter came with a submersible aquarium pump to circulate the cooling water and a moderately janky exhaust hose and squirrel fan to remove the gases and smoke generated when engraving.  In a few minutes I was able to get up and running, placing the pump in a vat of distilled water and routing the exhaust hose out the door.  All I needed to do was fix a poorly-designed ground connection (paint doesn't conduct electricity folks!) and adjust the mirrors to get a properly aimed and focused beam.

I was half expecting to see a satisfying lightsaber-like beam, but sadly, a CO2 laser only produces invisible infrared light. It does have the capability of blinding its operator without advance warning, however, so I was sure to order a pair of CO2 rated laser glasses to wear when working with the cover open.

The weakest component in the system is the software.  The laser cutter only works with MoshiDraw, a program that runs under Windows and functions both as a driver and structured drawing program.  It's buggy and confusingly organized, and the English translation is absolutely atrocious.  However, the program is quite functional once you figure it out, and is capable of completing a wide range of projects.


As a warm-up exercise, I first tried making some test cuts in paper, essentially using the engraver as an oversized, overpowered Cricut, those computerized die cutting machines used by scrapbookers to make paper hearts and doilies and such...  except of course with the added satisfying (and may I add manly) power of a death ray laser beam.

To follow up, I tried my luck with plastic.  Using two-tone copper/black laminated acrylic sheet, I cut and engraved a replacement for the laser cutter's own control panel, which I had enhanced with a few extra switches and knobs.

Cutting acrylic laminate
Completed panel
Installed panel

I used a similar material to make bookmarks engraved with a MakerMonkey logo I drew in Photoshop.

Lastly, I tried the laser cutter on plywood, scorching the same logo into the surface, making this custom engraved coaster.
Laser Cutting Plywood

The possibilities are endless for future things to make, but the laser cutter couldn't stay in the middle of the room forever.

First, it needed a permanent home, and of course something ordinary just wouldn't do.

Sunday, May 10, 2015

The Pizza Oven

Littler Monkey in the Oven
It all started last summer after reading an article in the June/July an issue of Make Magazine. The story described the construction of a DIY outdoor barrel oven made from bricks, welded steel parts, and a 55-gallon drum.   Able to bake bread, pizza, and other goodies from a wood burning file, such an oven seemed perfect for outdoor gatherings (keeping them outside!), and quickly made our short list for planned backyard additions.

This type of oven, known in Argentina as an "Horno Chileno", or Chilean Oven, is popular there for several advantages over traditional earthen ovens.  Because typical clay or brick ovens work primarily off stored heat, they require 1-2 hours of firing to bring them up to temperature and require periodic re-firing between sessions to bring them up to temperature.

Chilean Ovens, on the other hand, are "mixed-mode" devices that use a metal drum to create an isolated cooking chamber.  Since they operate over an open fire, they are much more efficient for occasional use, are ready to cook continuously in as little as 20 minutes, and can safely use scrap wood, paper, or even yard clippings for fuel.

Building the base
About six weeks ago, I was ready to start building, and created a base out of concrete block and brick.  Bricklaying is a messy process (at least it is for a novice like me), but it was fun and easy to do.  The most painful part is just obtaining the bricks in the first place.  I used about 320 tan concrete bricks, which I hauled in numbeous repeated trips from two local OSH stores.

Building the firebox

For additional heat resistance in areas directly next to the fire, I used heat-resistant firebrick.  Firebrick is much more expensive (and brittle) than clay or concrete brick, so I only used it where necessary, lining the firebox mortaring it together with refractory (heat resistant) cement.

For the bottom of the firebox, my trusty assistant Little Monkey and I welded together a fire grate from rebar and angle iron.  This would support the burning wood.
Welding fire grate
Fire grate installed

Little did I know that with the partially built brick structure and all the mortar that needed cleaning up that we were also creating the World's Coolest construction toy playhouse.

Construction worker on the job

For the cooking vessel, I scoured Craigslist andgot a $30 55-gallon drum that stored cooking oil in a former life.  I took it to an auto shop to sandblast the insides clean of paint, as food with paint fumes didn't sound very yummy.

To support the baked goods, I found two large industrial oven racks on eBay that I could bend to fit.  Each rack provided a generous 33" x 19" of cooking space, and fit almost perfectly inside, though I had to weld an extra inch of length to the barrel top to give them enough space.  I secured them with stainless steel bolts and nuts. 

Oven racks
Aka toy storage

Building the vaulted top
Now the tricky part.  For the vaulted arch, I mortared brick into the rounded shape using a framework of 2x4 cribbing supported by the barrel.  These temporary supports--when removed--would form an air gap where heated exhaust gases can warm the barrel on their way out to the exhaust chimney on top.

My new good friend Amazon Prime provided the parts for the chimney, including a 6" galvanized pipe, fire safe exhaust cap, and cast iron damper.

While the magazine article provided good general guidance, it lacked specific instructions in many areas, especially in the regards to the metalwork.  Fortunately, the absence of exact requirements left ample room for blissful improvisation and it's evil companion Online Shopping. 

Ready to use drum lid
Insulating oven door
The oven front was biggest metal part requiring fabrication.  The design required a heavy hinged door with a rest stop mounted to a form-fitting ring attached to open end of the barrel.

Surprisingly, I found an amazing shortcut in the Bustin Waste Drum Cover.  Complete with a naturally heat-resistant powdercoat finish, it almost exactly matched the carefully constructed metalwork in the article.  All I needed to do to complete it was to paint it black, add a spring grip to the handle, and insulate the inside with ceramic batting and an inner wall I fashioned from the old drum lid.

For the fire door, I found a ready-made fireplace cleanout door, fashioning a simple locking handle of of bar steel to complete it.  Similarly, for the cleanout, I used an existing metal air register as an air grille, adding a tray formed from galvanized sheetmetal as an ash drawer.  Both looked better than anything I could fashion from scratch myself.  Thanks again Amazon Prime!

Fire door
Ash drawer

Door thermometer
Inside heat sink
For finishing touches, I added a thermometer to the door and, after a test firing, added large heat sinks to the inner and outer bottom surface of the drum with the thought of increasing heat conduction performance and air circulation.

Here is the completed oven.  Once put together, IMHO it looks fairly legit.

All hail Smoko, the Chilean


It's taken a couple of firings work out some initial bugs.  For instance, initially I didn't leave enough expansion space around the barrel front and this caused a little expansion cracking when brought fully up to temperature.  Wood fires are also very sooty, and I had go back and seal the fire door and barrel surround with silicone to better contain the smoke.  Lastly, while I kept the original chimney height short for aesthetics, getting smoke blown in our faces was fairly fun-free, necessitating extending its height a little bit.

We've also learned a few tricks, such as first building a good fire and waiting for it burn down to hot coals before cooking.  That's when we've seen the oven reach its hottest temperatures, around 600 degrees F, perfect for crispy pizza.  We've also heard that hardwood burns much cleaner and longer than softwoods, so we're looking forward to trying that.

We're still learning how to best take advantage our new Chilean friend, but are sure it will continue to be a hit for many summers to come.