Archive for the ‘Engineering’ Category

Bed Frame

Thursday, January 12th, 2017

It recently became apparent that my son was too big for his toddler bed. As we searched for a twin bed at popular stores for children, I found that beds are grossly over priced. The bed my wife liked was over $600, not including the mattress!

We decided that I could make a better quality bed for much less than that, so I did!

Planning

I started out by drawing some hand sketches with rough measurements. I went through the process a few times, each time refining the plan so that it was more complete, and had more accurate dimensions. I also tried to simplify the material selection so there was as little variety in the lumber required as possible.

Bed Plans 2Bed Plans 1

We chose to paint the bed, rather than stain it. This allowed me to choose multiple types of woods which helped cut costs. Here is what was purchased:

Item Usage Quantity Item Price Total Price
4×4, 16ft (Redwood) Bed Posts 2 $13.97  $27.94
1×6, 24 ft Lower Bed Rails 3 $5.91  $17.73
1×4, 8 ft (Spruce) Head/foot board upper rail 1 $1.84  $1.84
1×1, 16ft (Poplar) Mattress Flange 2 $3.50 $7.00
4×8 3/4″ Plywood Mattress support 1 $38.27 $38.27
4×8 1/8″ Plywood Head/foot board material 1 $7.50 $7.50
1″ Slats (molding) Head/foot board decoration 40 Feet $.36 $14.45
Zinsser Primer/Sealer Prime 1 Gallon $19.98 $19.98
Blue Semi Gloss Paint Paint 1 Gallon $26.97 $26.97
Total Cost: $161.68

Total cost after tax: $175.90

Bed Posts

BedPostsThe bedposts are made from 4x4s meant for framing, which come in 8 foot lengths. The posts for the headboard are 4 feet tall, and the posts for the foot board are about 3 feet tall, so there was plenty of wood to get the posts from the 2 lengths that were purchased.

Obviously, the 4×4’s are way too fat for posts on a child’s bed, so I cut them down to 2.7 x 2.7 using a band saw. Next, I sanded them down to 2.5 x 2.5 by taking off .05 inches on each side using a reciprocating drum sander.

The whole bed was designed to be put together using mortise and tenon joints. The next thing I had to do is put in the mortises. For this, I used a mortise and tenon jig that my dad had. I used the largest setting for all of the mortise and tenons I had to do, which made set up pretty easy since I only had to do it once.

With the mortises all cut, I then needed to add a slot for the 1/8″ sheet of wood that will serve as the head and foot boards. I set up the router with the 1/8″ bit, and a depth of .25 inches, and centered it on the mortises, and made made a groove between the upper and lower mortises on all four posts.

Next, I took the hard edge off the corners by running them each through the router, using a small 1/8 inch quarter round bit.

I designed the bed posts to have a decorative groove near the top. The posts will protrude above the upper rail 2.5 inches, so that the protrusion is a perfect, symmetrical cube of material. I used the golden ratio to decide where to put the groove. The groove was made with the table saw, and is just a single kirf width.

Rails

BedRailsThe lower rails for the bed frame are made from the 1×6 planks of wood, and the upper rails for the head and foot boards are made from the 1×4 planks of wood.

The rails will be supported primarily by the mortise and tenons. I set the tenon jig to cut to a depth of 1 inch, so for the final measurement of the wood, one needs to add 2 inches to account for the tenon.

With the rails all cut to length, and complete with tenons, I routed the corners with the same 1/8″ quarter round that was used on the bed posts.

The shorter of the rails which will be used on the head and foot board require a groove for the head and foot board material. I used the same 1/8″ bit that was used on the posts, and added the groove on one side of all 4 rails at a depth of .25 inches.

Finally, some light sanding, and they are ready for paint.

Head and Foot Boards

The head and foot boards are made up of a 1/8 inch sheet of wood that is inset into the bedposts and rails. This will then be covered with decorative slats.

All I had to do was measure the opening, and add 1/2 an inch to account for the groves in which the wood will be set.

Once cut down to the proper sizes, the head board and foot boards can be assembled. This is done by placing one post down on the table with the mortises face up. The upper and lower rails receive some glue on the tenons which are then inserted to the mortises of the posts, and lightly hammered into place.

IMG_3719Glue is applied to the exposed grooves. The headboard material is then slid down from the top until it is seated in the groove on the post. Finally, glue is applied to the other end of the rail’s tenons, as well as the end of the headboard sheet, and the other post is tapped into place. The whole thing is clamped for a few hours until the completed headboard is dry.

IMG_3720I followed this same procedure for the foot board.

IMG_3722Lastly, slats are added. I took the 1 x 1/4 material and cut it down to the proper length to match the height of the inset area on the headboard. I also used extra material to make spacing jigs to help me distribute the slats evenly across the head and foot boards. They were glued in place. In addition to adding visual interest, the slats add a significant amount of stiffness to the otherwise flimsy 1/4″ material.

Painting

IMG_4014The whole bed was dry-fit together and painted all at once. I masked off a strip on the inner side of the long rails where I planned to put in the flanges that will support the mattress board.

IMG_4016I applied one coat of primer using a gravity fed spraying apparatus for the air compressor. This ended up taking forever due to the small amount of paint that the nozzle delivered. It took about an hour, but was reasonably evenly covered.

IMG_4021I let the primer dry completely, and then began applying coats of the blue paint using an airless sprayer. The airless sprayer delivered a much thicker coat, and after 3-4 coats of paint, I had used the whole gallon! It looked pretty good though.

Final Touches

Next, I cut the 1×1″ poplar to length, then glued and screwed it to the interior side of the long rails that had been masked off. This will serve as the flange upon which the mattress board will sit, and carry all the weight.

The very last detail before assembly is to drill the holes in the rails that will hold the headboard and foot board together. I used an angled countersink jig to put 2 shallow-angled holes on either end of both rails that will allow screws to hold it tightly to the posts.

With all the pieces reader to go, the bed frame could be assembled. The rails were lightly hammered into the head board posts, then screwed in place.

The foot board posts are then hammered into place on the rails and screwed in.

The mattress board was then cut to snugly fit between the rails, and then laid on top of the flange with the mattress placed on top.

Just add a pillow and some sheets, and the bed is completely finished!

Results

IMG_0238_e

The bed turned out great. It is super-sturdy. No rocking or creaking. The price was also exceptional. The paint has a few minor blemishes due to my inexperience with painting, but looks pretty good overall.

My son loves his new bed, and it’s sturdy enough for all the antics of a toddler.

Revolutionizing the Bicycle

Friday, September 5th, 2014

I had a great idea a few months ago. It was simply brilliant. It would revolutionize the way we bike. I couldn’t find anything like the idea that I had pictured in my head, and my brain immediately began racing with possibilities of prototyping this idea, patenting it, kickstarting it, and starting a business.

I quickly enlisted the help of a friend with a lot of experience with mathematics and mechanical expertise. Obviously, the idea sounds great to him too, and we started searching for away to accomplish what we are envisioning.

NonlinearCrankThe crux of the idea is to reduce wasted motion when peddling, allowing the cyclist to apply energy to his forward momentum more consistently and evenly. To accomplish this, I wanted to create a system where the crank arms do not move at a constant (linear) speed around the crank. This requires the left (red) and right (blue) crank arms to be independent from each other, but synced in their motion. This also requires a some type of gear mechanism that allows the crank gear (green) to move uniformly.

Having achieved all this, the result would be a motion where the leg spends more time pushing down in the front of the peddling motion than recovering on the upswing part of the motion. My theory was that eliminating the dead spot completely, and always having one foot in a power position, that cycling would be more efficient in terms of power applied over time.

We got to work thinking the problem through in our heads, and what the mechanism would have to be like. We at first looked at non-circular gears, but that turned out to not be feasible. Eventually we looked at planetary gear systems, but that was also very complicated. Every path we took though seemed to have a dead end, or so complicated that it seemed impractical.

RS4x_Exploded

Then it happened. My friend stumbled upon a company that had already invented this device. It’s called the RS4X (review of RS4X by Gizmag from 2005), and is made by a company called Rotor Bike Components. One of the reasons we didn’t come across this product during our preliminary research is that the company stopped selling them in favor of Q-Rings, or non-cricular crank gears. The company was actually founded around this idea in 1999.

What’s surprising though, is that they were not the first. A patent exists for this same design from the 1970’s. A man named Tom Traylor created the design, and applied for a patent. Unfortunately, he was not granted the patent (and unfortunately lost his $2000 filing fee). Similar ideas, it turns out, had been patented no-less than 5 times within the last 100 years, the oldest being an English patent from the 1870’s with a nearly identical implementation to Tom’s, and Rotor’s. Tom made a little write-up about his experience that appeared in Recumbent Cyclist News in 2004, which can be read here.

In the 1800’s, mechanical system were all the rage. It’s what people researched, designed, and tinkered with back in the day. It shouldn’t be surprising that this idea had already been explored so many times during the last century.

So why didn’t it catch on? I don’t have any definite reasons, however I have some theories.

  • The added complexity of the mechanics lends itself to more frequent malfunctions and failures.
  • The benefit is outweighed by the propensity of mechanical failure.
  • The advantages of such a system are actually negligible in practice.
  • The mechanism is too costly for mainstream usage.

Whatever the reason, the truth is that the idea just hasn’t taken off. I’d still like to try one to see what its like though. It was fun to think about. I suppose the real take away is that it’s hard to come up with a completely new, unexplored idea, but if you ever do, jump on it!

Arkanoid Cocktail Cabinet

Saturday, March 29th, 2014

Arkanoid-Logo-New

About 13 years ago (2001), my brother, dad and I embarked on a mission to create some arcade cocktail cabinets. My brother had bought some vintage arcade games at auction, and we both decided that it would be fun to own brand-new cocktail tables.

We got my dad on-board with the idea, which was probably the most important part, since he had all the tools and know-how. And if we were going to build 2, we might as well build more. We ended up creating 6 cocktail cabinets; one for each sibling in our family, one for a cousin, and another for a neighbor. This original endeavor is somewhat documented on my very old personal site.

The Cabinet

The first thing we did is measure an actual cocktail cabinet that we found at a local Marie Calendar’s. The cabinet was actually pretty terrible. It didn’t appear to be authentic, and was in bad condition. That aside, it gave us some basic ideas for size and construction.

IM000185

We build a rough prototype out of some old plywood that we had lying around in the garage. It was very crude, but it helped us cement down some measurements and figure out how we would do this with the actual cabinets. It was quickly built with ugly butt joints and no thought to finish in one evening. We then wrote down some final measurements and made plans for how to construct the final cabinets.

IM000209

For the final cabinets, we used plywood with oak veneer. We used 3/4 throughout with the exception of the top which was 3/4 and 1/4 laminated together to make a substantial 1 inch thick surface. The pieces were all cut out on the table saw. We decided to use dados throughout the construction in order to eliminate the need to nails and screws. We wanted the finished product to look elegant and not cheap.

IM000270

The bottom piece is made of particle board with a melamine layer on both sides. holes were pre-cut for a speaker, AC receptical, and fan. The power supply was also mounted to the bottom piece.

IM000314

All of the sides were fitted together and glued. The dados provided strong joints once glued. For the door, we attached it using european hinges instead of unsightly piano hinges that are common on arcade cabinets. Since this is for personal use, we made no effort to make the cabinet lock. The edges were all routed with a groove in order to accept t-molding, however some of the cabinets were fitted with edge-tape veneer instead.

IM000215

The tube is actually a cheap 19 inch CRT TV that we bought from Fry’s and then converted to accept the arcade video signals. For some reason, they sales person didn’t believe us when we asked for 6 19 inch CRT TVs…

IM000516

Of all of the cabinets, only 2 got 100% completed; mine, an Arkanoid, and my sister’s, a Mrs. Pac-Man. My other sister, who was in college at the time, didn’t want her’s put together since she had no place to put it, so it sat in storage in pieces.

Ten Years Later

My sister was hosting a family reunion, and wanted her cocktail cabinet for the kids to play on. I had agreed to finish her cabinet for her when she had a permanent dwelling. The time had come, but I didn’t have enough lead time to prepare it for the reunion. En lieu of her cabinet, I gave her my Arkanoid, leaving me with the unassembled cabinet in storage.

Over the last month or two I’ve been collecting all the pieces I needed in order to complete this game, including power supply, controllers, PCB, buttons, and the control panel overlay.

IM000213

I assembled the cabinet by simply gluing the awaiting pieces together. It went together perfectly. Even the hardware for hinges was already in place in storage, so there was little to do there. This cabinet had its edged veneered instead of using t-molding. This is was actually preferable to me as I found that I didn’t like the look of the t-molding on my original cabinet after a while. I stained it using a red-wood colored Minwax. This time I opted for a red stain over the brown that I used for my original. From there I spent a weekend putting a clear coat of Deft over it.

IMG_1606_edited

I took the original design file for the control panel overlay that I made back 10 years ago, and updated it significantly. I cleaned up some mistakes, and updated some of the graphics to look cleaner than before. (Before, I barely knew how to use Illustrator). The first time around, I printed them on photo-paper and put them under a thin sheet of plexi-glass. This time, I had them printed at ArcadeOverlays.com, and they turned out great!

IM000303_edited

We fitted all of the cabinets with Jamma. This made it easy to swap games in and out if we ever needed to. The Arkanoid 1 PCB needed a custom Jamma adapter whereas Arkanoid 2 comes with a Jamma connector as standard. I build a converter board for my Arkanoid 1 PCB so I could quickly switch between Arkanoid 1 and 2.

IMG_1607

I spent about an hour putting all the connectors on the wiring harness, and hooking up all the controls, power, and monitor. I hooked it all up on the bench, and verified that everything worked, and it did! Another change I made was using an LED strip for the panel illumination instead of bulky, hot incandescent lights.

IMG_1658

The control panels are made from sheet steel. I had a friend who works in a metal shop who bent them on his brake for me. I then drilled all the holes using a template I made in Illustrator based off of the design I had printed, and drilled the holes on a drill press. It was panted with black lacquer, and then I carefully placed the CPO sticker on. That was the most nerve wracking part!

IMG_1688 edited

Once I had all the electronics working, and ready to go, all that was left was to stick it into the box. I made a little box that you can see on the left for holding the PCBs. It fits 3; Arkanoid 1, Arkanoid 2 and Tournament Arkanoid. Everything fit like a glove!

IMG_1685_edited

I made some top artwork a while ago in anticipation of this project. The design was meant to be retro, and a little cheeky. I’m not sure that will be a permanently displayed… It was printed on a friend’s large format printer, and then I cut it out with an exacto knife. I have a new design that’s a little less in-your-face that I’m contemplating printing…

The Finished Product

IMG_1683_small

All-in-all, the cabinet turned out great. I’m very pleased with the look of the cabinet, as well as with the game itself. I quite enjoy Arkanoid, and enjoy having Arkanoid 2. It’s a little different but still familiar. I don’t think I’ll get tired of it soon.