Heat Box for Industrial Clay

After completing the DIY course at CMU, I was invited to TA the class the following year. The class size increased from 40 students to 60, so we needed an additional heat box for an assignment involving industrial clay. Here’s (most) of a how-to. I sort of neglected to include how I put on the hinges, but that’s pretty straightforward.

You’ll need the following:

The first thing to do is to cut all the panels to the correct size.

  • Left & right sides: 18″ x 18″
  • Top & bottom: 29.5″ x 18″
  • Front & back: 19.25″ x 29.5″

These dimensions worked for my 19/32″ thick plywood sheets. Based on how things are put together, the back and front panels need to be adjusted in the height dimension (19.25″).

I don’t have a table saw at my place, so what I did instead to cut really straight lines is to clamp my straight edge to the plywood for cutting with a circular saw.

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Use the thickness of the Sharpie o your advantage! It tends to be pretty close to the thickness of circular saw blades, so line up those teeth with the cut line.

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Apparently finding a length and dividing by two is above my pay grade. These two sheets were supposed to be the same length, cut from one sheet of plywood.

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Well, after fixing the length of the sheets, I tacked down all the nails along the edges a 1/2″ in from the edge of the plywood sheets and tried to get them evenly spaced with at most 5″ between the nails.

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Apply glue to the edges that are supposed to be joined…

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All edges glued and nailed together. The plywood was just slightly more bowed, so I opted to use a bar clamp to keep to edges tightened down while the glue dried.

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The back was put on pretty similarly: evenly spaced nails, glued faces.

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I’ve somehow managed to survive without a compass to draw circles, so I just used my calipers to measure the size of hole to cut (2″ for my lamp) and scribed it to the center of the top of the box.

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If I had a 2″ hole saw, I probably would have used that here, but instead I just drilled a while bunch of holes to I could cut through them all with the routing bit on my Dremel.

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After cleaning up the hole with the sanding drum, I added 1/4″ chamfer on the underside to accommodate the taper of the lamp bell.

I sort of just forgot about documenting the last couple parts (putting in the insulation, foil, hinges, and handle), so… here’s a picture of the final product:

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Oh… and here’s a closer picture of the door-prop:

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If you’re interested in putting the same door-prop on yours, I’ve uploaded the STLs to a Thingiverse “Thing.”

As a final note, a 60W light bulb works fine, but an 80W would be better if there’s a lot of clay or if the door needs to be opened and closed really often.

Kranich LG G4 Phone Holder for ’98-’02 Saab 9-3

Yeah… the title is really specific, but that’s because this phone holder was designed specifically for my phone to fit my car.

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I’m the third owner of this car, and it looks like the second owner broke off the cup holder when he punched a cup of coke out of it. I used to have one of those suction cup mounts, but they sort of suck during the winter and they get in the way of my Heatshield (get one to protect your dash from UV).

I made use of the gaping hole in my center console by sticking a chunk of phone-holding plastic into it. Oh, and by the way, my phone is an LG G4 with a Kranich extended battery.

Files of the model are hosted here on my Thingiverse page.

Sharpening a Reel Mower (Push Lawn Mower)

My WordPress is long overdue for updates, so I’m just going to do a bunch at the same time while I have a little break from schoolwork.

This post won’t necessarily be helpful as a how-to post, and more of a this-is-possible post, because it’s way easier to learn this from a video or from someone else than it is to learn from pictures and text, but here goes.

I started a little company (really just some online postings) for a sharpening service while I’m in Pittsburgh, because for some weird reason, I couldn’t really find anyone in the area who offered knife sharpening. Anyways, I got a call from someone asking if I could sharpen a push mower, so after watching some videos and reading an Instructable, I figured out how. Before I dive into steps, if you want to follow along, you’ll need the following tools:

  • Flathead screwdriver (popping off e-clips and adjusting blade)
  • Valve grinding compound
  • Grease
  • Cordless drill (makes things a little easier)

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So the first thing to do is to pop off the wheel cap, e-clips (retainer rings), and wheel. This way, I could rotate the blades without the wheels spinning around.

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After that, I popped off the little gear. Inside it, I could see how the ratcheting mechanism worked. There’s a little almost trapezoidal shaped metal bar that sits in a slot in the shaft of the blade assembly. Pushing the mower will engage the wheels with the blade assembly, spinning the blades, while pulling the mower will disengage the two parts, so the blades stop spinning.

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There are two screws on each side of the mower that adjust how close the stationary blade is to the spinning blades. For sharpening, I adjusted them a little closer together such that the spinning blade assembly could still rotate but with quite a lot of force. The blades will be used to grind each other to sharpen everything up.

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I loaded all the edges with the valve grinding compound, which is basically just a bunch of sand in some sort of past-like suspension. The abrasive will allow metal grinding that sharpens the blade edges.

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One of the videos suggested using a cordless drill to rotate the blade assembly. Unfortunately, my cordless drill chuck didn’t fit over the axle. The Instructable suggested flipping the ratchet assemblies (left to right and vice versa) to “run” the mower backwards, so that’s what I ended up doing instead. Important note… spin the blade assembly backwards and not forwards, otherwise you’ll be dulling the blades instead of sharpening them.

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After running the blades backwards for some time and cleaning off the valve grinding compound, I could see that metal had been removed from the leading edges of each of the blades.

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After cleaning off all the grinding compound, I adjusted the blade distance again such that the blade edges were touching along the entire length but not too difficult to turn. To make sure everything was nice and sharp again, I grabbed some paper, stuck in between the blades, and checked the sharpness for each of the blade along the entire length of the mower.

The last step was to clean out the old grease from the gear and ratchet assembly, pack with new grease, and reassembly everything (making sure the mower blades spin in the correct direction).

Hope that was useful to someone. Again, there are plenty of Youtube videos, and they’re probably much more helpful for learning how to do this.

DIY Final Project

The only requirements for this project were to make something that makes us happy, and to not make something too large that a 5-year old couldn’t carry it around. It took me quite a while to think of a project, but I finally settled on a pen roll. This was something that I had wanted to make for a while, but never got around to it, so I figured I may as well spend the time to get an assignment out of the way, too. It was also sort of a nice way to physically gather all the things that were given to us over the course of the class.

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First thing, as always… sketches. There are some irrelevant things on the page, but the two on the right are pertinent to the project. I like having round holes to slot in the writing implements. The wavy cutouts were also pretty appealing, but I was worried that the fold over the top of the pens would get in the way of nice rolling.

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There are some not-so-visible sketches at the top, but those were just more of the folding top design. This is where I start really thinking about how things are going to fit in the pen roll.

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This is the sort of final project sketch before I started fabricating. I did end up switching the position of the eraser and knife, because I was worried that the eraser would get in the way of removing the knife.

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There is a sort of assembly sketch for me to figure out the layering of all the parts. I had originally intended to skive and fold each of the round cutouts, but when I started actually fabricating, I decided against this, because it would have been too difficult, and I did not really have a proper skiving tool for this.

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Laid out everything on a slightly extended piece of paper. The leather I had to work with was just a little bit over 12 inches, so I extended the 8.5″x11″ accordingly. Layout is everything from here, because I only had enough leather for one attempt. The assignment was due the next day, and I had no room for a screw-up.

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I trade out all the parts that I wanted to go into the pen roll, along with centerlines, and stitching lines. I had to use a ballpoint on the right side of the layout, because it was taped over, and pencil wouldn’t draw on it. (I should have done the layout on the other side of the page, but oh well…)

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After taking down the paper layout to the first sheet of leather, I used a spacing tool to mark out all the stitching holes. This also had the added benefit of keeping the paper from sliding around the surface of the leather when I started cutting out the holes.

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All holes cut out! I actually had to re-hone my X-Acto knife between cutting each hole. I kept a stropping leather loaded with jeweler’s rouge on my desk for that purpose.

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Before stitching, I had to burnish all the inner edges of the circles that I had cut out. I used a burnishing tool (figures) and some stuff called Gum Tragacanth. Basically, the stuff dissolved the leather, and after it dried, the leather would be nice and fused together.

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I cut out a sheet of denim from a pair of torn jeans that I probably should have stopped wearing long ago. I made sure to trim the denim just shy of the perimeter stitching lines, because I did not want the denim to interfere with the burnishing later. I also used some flexible glue to tack the denim down to the back sheet of leather.

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There’s the strip that ends up going around the entire pen roll to keep it closed. The front of it is leather, and the back is another strip of denim. I used more glue to keep it together and limit the fraying of the denim. I stitched the lengths of the strip first, before mounting it to the rest of the pen roll.

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There it is anchored to the back piece of leather. The tie-off for the stitching ends of being hidden under the inner sheet of leather.

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After many, many more hours of stitching, I ended up with this. I decided to not have the partitioning stitches run all the way to the end of the perimeter, because there would have been stitching hole alignment issues. The gap allowed me to not have to take the alignment into consideration.

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Perimeter stitching finally done, along with trimming the edges. Last step was to burnish all the outer edges.

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The things that were given out in class were the 3 COPIC marks, one regular Sharpie, a fine tipped Sharpie, BIC Cristal, and two colored pencils. That’s not even including the sketchbook!

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Some minor issues with the edge not bring fully burnished, but that can always be fixed later.

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That’s it! I think that was a pretty good way to wrap up that class. Hopefully, I’ll get to be a TA next year and see what other awesome ideas students come up with.

Mastering Mockups

So the point of this project is to prototype how an object might look using paper, expanding foam (I actually didn’t end up using this), and design clay (industrial plasticine).

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First thing is always sketches! I actually spent a lot more time just looking at ladles than sketching out different designs. I was pretty much set on a design anyways, but sketching is sort of part of the project.

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With the terrible hand illustrations above, I tried to explain why I selected a ladle for the project. Basically, the curvature of the handle on most ladles (and flatware in general) is facing the wrong way. For almost any other hand tool, the convex side of a handle tends to fall into the fingers, while the the concave side usually is where the thumb rests. Ladles and flatware have to sort of stupid curvature, which makes them all really uncomfortable to use, especially when trying to pick up a small bowlful of soup.

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To make the paper mockup, I first had to go into CAD to make a hemisphere for the bowl part of the ladle.

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And a pretty rough near-pyramid for the bump in the handle.

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The hemisphere made in Solidworks was exported as an STL then imported into Meshlab. Using the “Quadric Edge Collapse Decimation” tool, I reduced the number of faces. With the new low-poly STL, I simplified bowl part along with the handle bump to Pepkura, which was used to generate unfolded paper models.

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The instructions for the assignment were to laser cut these, but with the end of semester drawing near, the line for the laser cutter was quite long. Instead, I just hand cut the parts.

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The cardstock doesn’t take to folding too well on its own, so I had to scribe everything first in order to fold it nicely.

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All folds were creased prior to gluing. I used a toothpick to apply a thin coat of glue on each of the tabs.

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The handle bump seemed to be pretty good. This is the part of the project that probably should have been filled with expanding foam, but the volume was so little, and it was actually pretty stiff by itself, so I decided to skip out on the foam-filling part.

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The long handle was formed with two long strips of cardstock, scribed into approximate thirds. The outer piece was scribed just a little bit wider to compensate for the thickness of the paper when folded. The bimorph allows my to shape the hook at the end of the handle along with help to maintain the shape of the handle better than a single sheet of cardstock.

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Paper part seems to be coming along just fine.

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I probably spent a little too much time doing this. Design clay is very soft when heated, but once it is cooled, it retains its shape quite well. It cools sort of quickly, so after slapping on a bunch of clay and then carving down a bit, I had to put the entire part back into the hot box. I had to repeatedly put the part in, take it out to smooth, and heat again to get the final shape and finish.

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That’s it! Hopefully I’ll get some more design clay to work with in the future. It definitely was quite a bit of fun, and it’s nice and reusable.

The Desk Mount Dilemma

Despite the title suggesting that this is a desk mounted clamp, the professor gave to OK to create any sort of clamping device to hold an object. So instead of making another phone dock, I decided instead to make a bike mount for my phone.

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So as always, the project started with some sketching. Seeing as the clamping mechanism itself was the most important part, I decided to start my sketching with the mechanism. The screw-assembled pipe clamp mechanism is probable the simplest, go-to method, but I wanted a way to be able to take off the clamp and put it back on without tools. A cam-locking type device could have done the job, but I decided against it, because it required too many parts. The sketch on the right is similar to what I eventually settled on.

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The next step was to CAD it up and print it off on my 3D printer! Except…this first design ended up sucking pretty bad. The dimensions were all a little out of whack. First off, it didn’t fit around the handle bar, because the diameter of the clamp was too small. Also, the holes for the pins were much too tight, preventing any of the parts from pivoting. Even if it the parts did fit, the straight clipping pieces (the parts that look like a link in a bike chain) would not have had enough flex to allow the clipping pin to snap into place.

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So next, I decided to make a sort of hole sizing tool. I made a bunch of different diameter holes to figure out what would be the correct size for a pivot, and what would be good for a press fit.

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This time, instead of making all the holes the same size, I made all the holes on the outer faces of the clamp press git holes. The two inner holes allow for parts to pivot more freely. The pair of part for clipping are now bow-shaped instead of just straight, allowing for enough flex for the part to snap into place.

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Having learned my lesson with the poor fitment of the pin holes earlier, I printed off a smaller part to test fit around my phone. This was nice and snug, so I went ahead and made the full version next.

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All the pins were made with a Dremel and file. There isn’t much more satisfying than cleaning up a rough Dremel cut with a file and the brushing the file clean.

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And there’s the part! The standoff block that interfaces between the phone holding parts and the handlebar clamp also helps to offset the phone such that it site centered on the handlebars.

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There’s the clamp on my bike! The phone is inserted into the holder by sliding it in from the bottom. This ensures that if I do crash my bike, my phone will most likely stay with the bike instead of being ejected forward.

Hope you guys enjoyed looking through this again!

The Molding Mystery

I’ve played with silicone molding a couple times before, but this is the first two-part silicone mold that I made. There were some size limitations on the project, but it was otherwise pretty open-ended.

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It actually took me a while to find something to mold, and then I remembered these little pigs that I had laying around from testing my 3D printer. As is evident from the above image, this print went particularly poorly, as the top of the pig wasn’t completely filled, and the print layers are very obvious. If I tried to mold this, the silicone would seep in everywhere and would be disastrous.

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So the solution was J.B. Weld! I originally wanted to use Bondo, but I didn’t have any on hand, and the Bondo would have been pretty porous after sanding. I knew J.B. Weld sands pretty well, so I just used that instead. The finish was really lumpy, so more had to be done after it fully cured.

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After some 120 and 400 grit sandpaper, the piggy was pretty smooth, and all the holes were filled in.

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Before building forming the mold, I made some sketches to get an idea of where to part the mold and place the sprue.

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Piggy in mud! The first step was to bury half of the pig up to the parting line in clay. It’s a little tilted here to minimize the undercutting. The silicone is pretty flexible, so some undercutting near the parting line and near-vertical walls are acceptable.

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I used the end of a sharpie to poke some divots into the surface of the clay. These are for aligning the two halves of the mold later. Using some more clay, I sealed the edges of the foam core box built up around the clay block. It was sort of like caulking, but way more relenting. The next step was to mix and degas the silicon mixture and pour into the top of the box.

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After waiting 24 hours, I pulled everything out, removed the clay, and inverted the silicone block. I then placed a straw flush with the feet of the pig and built up some clay around it for the sprue.

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After both sides of the silicone mold were completed, I could remove the original pig and the straw. Next, I poured in the polyurethane casting resin. Ir seemed to come out pretty well. With some sanding and filing, and I was able to remove the sprue that was also cast. There are some bubbles on the feet, which I probably could have gotten rid of if I had degassed the part after pouring the resin.

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That’s it! The parting line is visible on the cast part, but it’s not too noticeable.

And as a mechanical engineer, I needed to get the orthogonal views of the pig. Thanks for checking this out!

Transforming Takeout (Phone Box + Dock)

The simplified problem statement for this assignment was to design a take-out container that would serve as both a was to take food to go and then “transform” into something else, like a plate, for eating.

Students were given some leeway in the project with a more general problem statement. Basically, the more general challenge was to create multi-purpose packaging for anything. However, the requirement was that the box be only made out of cardboard or cardstock. That meant no other adhesives or fasteners.

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The first thing I did was actually look at a bunch of pictures online of different food containers, but that wasn’t really anything that grabbed my attention. I sketched out typical Chinese take-out box with a spoon keeping the box together, but that seemed like sort of a flawed design. Taking out the spoon would just cause the box to fall apart. I’m not really sure where I got the inspiration to work on a phone box / dock, but I start sketching out those ideas pretty soon.

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Basically every phone sold comes in some sort of cardboard or cardstock box, most of which as discarded immediately after the phone is unpacked, so I figured it might be a good idea to come up with a design that furthered the life of the box. I sketched out how the box might look and how the phone and charger might be integrated into the box.

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Here’s where I really took my first stab at figuring out how to fold this box. I first sketched the outside of the box and determined which faces should be solid and which ones were permissible to part. I then added folds and the hidden parts of the box along with the sheets that would “jig-saw” together to keep the box from falling apart.

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Before trying to lay out the pattern for the box on cardboard, I grabbed a couple flat sheets and made a mock-up phone out of cardboard, too. That cardboard phone would serve as the form around which I made all the other dimensions.

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With a straight edge, pencil, and marker, I marked out everything carefully. In the above layout, there’s actually an extra segment on the left end of the pattern. I had to trim the extra segment out and shift a couple lines toward the right.

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After cutting everything out, I used a pretty dull pizza cutter and a straight edge to pre-crease all the fold lines. I had some issues with pressing too hard and tearing through the one side of the corrugated cardboard, but this was my first prototype, so it didn’t really matter.

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After making a couple folds, it became pretty clear that I had to trim around the outside of the pattern by about 3mm to compensate for the thickness of the box in order to make sure the walls of the box ended up straight up and down.

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With some tape, I was able to hold the first prototype together to get a picture of what the product might look like in the end. Seems fine so far…

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After quite a number of hours with Solidworks, I had the pattern for the box along with the shelves and the charging cable holder assembly. These were then laser cut out of cardboard.

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Here’s a close-up for how the charging cable is being held in place within the assembly.

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Assembling this proved to be a little bit difficult, but doable. This also served as good practice for assembling the final one that I would end up submitting.

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When laser cutting my final pattern, I had issues with the laser intensity. Despite using the same cardboard and laser power and speed settings, the final pattern did not cut properly. Using a headlamp to backlight the pattern, I was able to trace the cuts with an X-acto blade to free it from the rest of the cardboard.

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There’s the final pattern for the phone box + dock. I added two semi-circular cutouts for the tab at the bottom of the box to allow users to pull out the tab more easily. The parts for holding the charging cable had to also be altered to compensate for the off-center mounting of the cable.

Mak_Anselm_ps2_101_productMak_Anselm_ps2_102_product Mak_Anselm_ps2_103_productAnd those are the pictures for the final product! For a short video of the product unboxing click on the following Youtube link: https://youtu.be/UXCUxXPWd7k.

Coffee Cup Conundrum

This is the first “problem set” assigned to students for the Special Topics in DIY Design and Fabrication class at CMU. The students were given a couple different design goals with different target audiences and were required to select one of the target audiences.

Being a pretty typical mechanical engineer, I decided to go with the design that required assembling.

As always, I start the ideation process with sketching; however, I had to document the sketches much more that I am usually accustomed to, as the process of sketching out my ideas is part of my grade.

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The first thing I did was write down the requirements of the design. After that, I wrote up some other design considerations to sort of guide the design. Once those requirements were out of the way, I could start actually sketching out some ideas.

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One of the first considerations was where the fingers would go. Initially, I thought having two fingers above the indentation and two fingers below would be the most stable. The size of the cup would force me to change that later.

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Once I had the basic idea down, I had to figure out how to actually make this cup holder out of multiple parts and how it might be assembled. This was an idea for having two mirrored parts that would snap together around the cup. The acrylic parts, however, would be really long and skinny, making them structurally unsound.

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Here, I tried to get an idea of a fastener for attaching the different parts. The sort of wedge-shaped clip would make it to the final design.

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I wish that could have been the final design. I guess the “assembly” could have been interpreted as stabbing the cup with the pencil.

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In retrospect, this probably should have been my final design. The reason I had ruled it out was that one of my personal requirements from earlier was to have a design that could be assembled onto the cup without picking up the cup. With careful measurements, this would have been possible in this design, but I decided to go with something a little more flexible.

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Instead of having one piece retaining the top of the cup, I decided to go with two pieces, so this could definitely be assembled onto the cup without picking up the cup.

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That’s the isometric-esque sketch o the product. I ended up having to remove one of the steps in the handle to compensate for the size of the cup, which was much smaller than I expected.

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That was the model made in Solidworks. Of course, it did not end up fitting that well, and I did not have quite enough time to make multiple cuts to make sure everything fit really snuggly. The translucent part was the handle part before bending. I used a heat gun to get the bends in the final product.

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And there’s the final thing. There were definitely quite a number of issues in the design, as i was no all that stable and was in fact a little too fragile. Plenty of the other submissions in the class were far better… so I decided to step up the amount of effort I was putting into this class by quite a bit for my next submission.