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.

Welding

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.

Painting

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.

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.

MoshiDraw

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.

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.



 

Fun with DIY Unlicensed Medical Devices

FDA, AMA meet DIY

I'm not a doctor.

Nor do I play one on TV.  But who needs medical credentials when there is good making to be done!

Recently, I had the opportunity to build something different--a quick project that was simple but rewarding.

A few months ago a good friend mangled her arm in ATV rollover.  After several surgeries, her parts are back together (more or less), but her recovery entails daily hours of physical therapy to regain flexibility and strength.  The official routine is done with simple weights and manual devices, is repetitive and monotonous, and requires constant focus to maintain proper form and pressure.

As far as I know, being shirtless conjoined twins is not a requirement for the therapy shown.

I decided to I might be able to help with a particular exercise, one to extend the wrist range of motion in rotation.  My first thought was that there ought to be plenty of commercial mechanical devices on the market to help automate the process.  I looked, but except for a few vague references to mostly description-free items that could be purchased overseas in bulk, they didn't exist... yet.

It could be useful, I thought, to use an electric motor to perform the rotation, as it could rotate back and forth, performing a perfectly repeatable motion with a user-adjustable torque limit in each direction.

The "Wondermotor"

The first order of business was to find a suitable motor.  By lifting a one-gallon jug of water at the end of a 1-foot stick, we estimated that we needed up to 8 foot pounds of torque (since one gallon weighs 8.3 lbs).  That's pretty tall order for a low-voltage motor, but I found exactly one readily-available candidate--a 12-Volt Wondermotor ($69) on Amazon--that fit the bill.

It has a built-in worm drive to slow the motion and some impressive specs, and I'll have to remember this one when it's time to build powered go carts for the little Monkeys.

It used to be that you had to make stuff like this yourself

For power control, I got a small PWM motor speed control board ($10), also from Amazon, along with some switches, connectors, and miscellaneous parts.  Some pipe from the hardware store, and a cheap angle finder gauge from Harbor Freight completed the parts list.


I mounted all the components on some scrap lumber, elevating the motor tied to a block of wood with a pipe support strap.  I built a handle out of a bicycle grip, a galvanized pipe nipple, and PVC pipe fittings, and mounted it to the motor through an oval hole drilled in the pipe nipple.

For some reason this reminds me of that Simpsons episode where Homer bulks up just one arm and uses it to hustle folks arm wrestling.

To power the motor, I used a spare 12-Volt wall wart wired as input to the motor speed control.  I wired the output of the control to the motor, passing through a two-way momentary DPDT toggle switch to allow the motor to change directions.

The idea was to have motor stall when the user's wrist reached its end of motion, suddenly increasing the load.  By adjusting the power/speed control, one can get the unit to exert the same force for every rotation.

Here is a video of the device in operation during initial trial tests...  

I got lots of funny looks from the security guards that morning.

and upon delivery.