Tuesday, April 20, 2010

Walnut was the most popular choice this semester.

About a decade ago, give or take a year or two, I registered for a woodworking class. I took a LOT of unnecessary electives while I was getting my bachelor’s degree (the one semester I only took classes required for my major and minor was the most miserable semester ever), because I have wide-ranging interest and because I like having “fun classes” to help me relax. Although I love wood and had had some prior woodshop class experience, that did not end up being a fun class. Just a few weeks into the semester, I was overwhelmed and stressed out by all that was required for the class, and tearfully withdrew from the class. When the teacher signed the card allowing me to drop the class, he told me I should come back and try the class again when life wasn’t quite so stressful.

“Less stressful” is, of course, a relative term. However, having finished all the courses for my master’s degree and just needing to finish up my thesis, this semester seemed like a good time to follow the woodworking teacher’s advice and come back and try the class again. I enrolled, this time already knowing what was expected in the class (the requirements have not really changed in the past 10 years). The class was on Tuesdays and Thursdays from 8 in the morning to 11. Yeah. Pretty sure that’s the only time I have ever voluntarily enrolled in an 8 am class. Lab times when we could work on our projects and assignments were Tuesdays and Thursdays from 7-10 pm. Do the math, add in that on Thursdays I had to stick around to TA a 3-5 lab, and you will see that I had some very very long days on campus this semester!

I’m really writing about my semester project, and will not have in-process pictures. But just to give you more visual stimulation, here’s a picture of my turning project, a small bowl made from local walnut. It was my first bowl ever (and now I want to get some bowl gouges so I can make bowls on my own lathe), and I managed to get fairly impressively thin walls on it!

Early on in the semester we needed to turn in working drawings of our projects. I decided to make a desk. Mostly because I do not have a desk. I chose walnut because I tend to prefer dark woods—and about half of the class also had projects partly or entirely out of walnut as well! Sometimes it’s nice to be in with the in crowd. I modeled my desk in Solidworks, which meant that I first modeled each individual part, then virtually assembled the desk. I first sat down and measured the comfortable height for the writing surface. I’m short, and usually feel like desks are at armpit level, which is not very ergonomic. I also measured the height I would need to be able to scoot my legs under the desk. The difference between those two measurements drove a lot of my design choices.

A few key features: 1. The top is not as thick as it looks. The center is ¾” thick, with thicker pieces framing it. The top nests over the frame of the desk. This meant that the top of the drawer had to be at the same level as the bottom of the edge pieces of the top. 2. The drawer is not as deep as it looks, either, the drawer is only half as deep as the drawer front. This did complicate matters somewhat, but it was the look I wanted. 3. The legs are tapered on the inside faces. 4. For decorative purposes (and some added stability), a stretcher and three slats are placed between the back legs. If you were paying attention to point #3, you may be able to figure out what one of the complications with this feature was. The stretcher went into the legs with a mortise and tenon joint. I made the mortises before tapering the legs, having already used my solid model to figure how deep they would need to be. This was not difficult. However, for the stretcher…well, I needed to make the tenons to fit into a slightly angled surface! The taper angle was only a little over 1°. I made the mortises in the top of the stretcher for the slats, then carefully transferred the necessary angle to the adjustable miter gauge on the table saw, and carefully cut the angle. When I took the angled stretcher back to the legs to check the fit, I discovered that I had inadvertently cut the angles the wrong way, so the holes for the slats were now on the bottom! Other than that, the fit was pretty good…. I filled in those holes with pieces of maple—not that anyone will ever see them, but it makes it look slightly more intentional and less like I was patching!

Assembling and gluing the project was another adventure. I had designed the pieces to all fit together without screws or nails. I used a lot of dado and rabbet joints, so that the various components fit neatly onto each other even without clamps to hold them in place. But it was a lot to do, so when it came time for final assembly with glue, my teacher recommended I use a polyurethane glue that would allow me greater working time than regular wood glue would. I followed his recommendation, and the two of us were able to glue and assemble the whole thing ourselves, whereas others in the class often needed to have four or five people doing the glue-up. However, the stuff did seem to take forever to cure, so I quite cruelly monopolized 19 gluing clamps when everyone else in the class was trying to do their final assemblies, too! And that was just for the frame, not the top or drawer. Also, compared to wood glue, polyurethane glue is a pain in the neck to clean off after it squishes out (and foams out) from the joints. I will not show you close up photos of the desk, because you would be able to spot some of the damage I did to it with poor chisel-handling skills in the post-gluing clean-up. Oh, well.

At this point, I was rapidly running out of time to finish in time for grading. Since we could only get into the lab when the TA was there, I decided I wanted a little more flexibility. So I kidnapped my project and took it across the street to the lab where I did the experiments for my thesis. Because our research machine is currently not in the lab, there was a nice empty area of floor space for me to put my desk for finishing! I finished it with four coats of a penetrating oil finish, which brought out some beautiful colors in the walnut. There are at least two species of walnut in the desk. Some is the same kind of local walnut that I used in my bowl, and some is…well, I’m not sure what it is or where it’s from, but the coloring is different. When I was first preparing my pieces, I was careful to arrange them so that the color variations would be aesthetically pleasing.
All in all, I’m quite happy with my desk. It looks good and it fits me well! Using solid modeling was extremely helpful, because I could easily see what it would look like, “making” the parts before I made them helped me think about the best ways to make them for real as well as indicating potential problems, and it was easier to figure certain dimensional issues (like the fit of the stretcher and slats) than it would have been if I had drawn it by hand or with a 2d drafting program. Now I just need a bigger place to live so I have somewhere better to put it than at the end of my couch….
Oh. And my teacher’s comment on it: “Wow, it looks like the drawing!”

Monday, January 4, 2010

Just because I could, Part III

In the previous two installments, I made a release-paper-covered polystyrene foam mold for a 9” high, 12” diameter carbon fiber bobbin lace lampshade, worked the lace, and smooshed a 24-hour epoxy into the fibers.

The next morning (yes, less than 24 hours later), I returned to the lab to attempt removal of the composite lace from the mold. The first task was to remove the wax-coated toothpicks which I had used as pins. I used a pair of pliers to grip the toothpicks, and pulling out with a slight twisting motion was usually sufficient. However, three toothpicks did break off as I tried to remove them. Considering that I used an entire box of toothpicks on this project, though, three breaking off is not bad. After removing the toothpicks, I went back and focused my attention on the broken stubs, and successfully removed them as well.

But even with the toothpicks removed, the thing was still stuck to the mold. However, my experience with removing the toothpick stubs pointed the way. See, I had grabbed one of the popsicle sticks that are stocked in the lab, wiggled it around under the lace to loosen the resin from the paper, and then turned it on edge to raise the lace high enough to reach in and grasp the stub. So to prepare to remove the shade from the mold, I slid the popsicle stick under the lace at an already loose point, then wiggled it around under the entire thing.

Finally, I pulled the slightly-flexible plaits along the bottom out and up enough that they were on the side. As you can see in the following picture, once I had everything loosened from the release paper, it slid off pretty easily. I had designed the top well enough that it kept everything stable as I pulled the basket-like structure off the mold. I just grasped the sides with my fingers, and pushed on the top of the mold with my thumbs. This was probably the quickest and easiest part of the whole project!
Next, I carried my carbon fiber composite basket across the street to my lab where I’d left the lamp hardware and assembled it all. I used a small piece of poplar as a support plate for the shade. After taking the project up to show my teacher, I took it home and hung it up in the dim corner by my fiction bookshelf.
I would like to put up another swag hook a little further from the shelf so that the lamp doesn’t block my view of the artwork on the top of the bookcase. But that will be a project for another day. In this slightly blurry view from the interior, you can more clearly see the lace pattern. The next picture, also an interior shot, shows the top pattern.

Almost everyone that I told about this project was intrigued, even if they were stumped by either the term “bobbin lace” or “carbon fiber” (or in some cases, both). This is definitely an example of how my wide ranging interests in making stuff come together in an unexpected way! I am fairly confident in stating that I am the only person in the world with a carbon fiber composite bobbin lace hanging lamp!
(Doesn’t it make a pretty pattern on the walls and ceiling? I should put in a liner to make it more of a lampshade though, and I should probably do that before friends come over for my birthday and burn their eyes out staring raptly at my fascinating lamp.)

Saturday, January 2, 2010

Just because I could, Part II

In my previous entry, I described how I made the mold/working pattern for a composite carbon fiber bobbin lace lamp shade for my Composites semester project. In this installment, I will describe how I actually worked with the carbon fiber to make the lace.

First of all, I’m sure some people are wondering what carbon fiber is. (I’m pretty safe in that assumption, because some people have asked me, “So, what is carbon fiber, anyway?”) Carbon fiber is used for a lot of high-end uses where strength and low weight are necessary. New planes being built by Boeing and Airbus right now are being made largely from carbon fiber—the Boeing 787 has been in the news lately. Carbon fiber is made by taking another material with high carbon content and basically burning off whatever isn’t carbon. Sounds kind of weird, but it works. So you end up with long, continuous strands of solid carbon. This can then be woven into fabric or used in filament winding (where the fiber is wrapped directly around a mandrel to make the part). If I had followed my original plan to make laptop sleeve, I would have used carbon fiber cloth or prepreg (cloth impregnated with activated resin so you don’t have to add it when you are making the part). But for my bobbin lace, I took advantage of the fact that the lab had several spools of fiber for filament winding available.
At 44” long, this would be the longest piece of lace I’d ever made. Also, as you can see in the preceding picture, the fiber (which is made from many individual strands) is much wider than the thread I am accustomed to working with. So I needed a special set of bobbins to accommodate this unusual material. I got some craft dowels, cut them to three inch lengths, drilled holes in the end, and glued in long nails.
Now, winding bobbins is always my least favorite part of making lace, and these were awful to wind. I took the bag of bobbins and the spool of fiber over to the machine shop, where I could be available to assist students working on projects for the class for which I am a lab assistant. Not surprisingly, everyone looked at me oddly and asked what on earth I was doing. I got that a lot in the course of this project! I miscalculated how many pairs of bobbins I would need, and wound several more than necessary. That turned out to be a good thing.

Finally, I was ready to start the lace. I placed a couple of clamps on the worktable in the composites lab, and laid a piece of release paper across them, to make a cradle to hold the mold/pillow/whatever you want to call it. I also got a box of toothpicks and rubbed a wax mold release into a few handfuls of them. The toothpicks would be the pins for the lacemaking. As usual, I hung the pairs of bobbins on in a diagonal. Honeycomb is a very easy ground to work, which is one reason I chose it for this project. It also can cover quite a bit of area rather quickly, which is another reason. Now, I had originally thought I would apply the resin to the fibers a few inches at a time while working the lace. Quite sensibly, I revised my plan and placed all the fiber for the whole thing before adding the mess of resin. As I mentioned in my previous entry, I have not worked on a bolster-type pillow before. I found that it actually wasn’t much harder than the other pillows I’ve worked with. The only real problem was that the strands of fiber kept getting caught in the heads of the nails on the bobbins, which got annoying. But it worked.
In the preceding picture, you can see the bobbins hanging on the pillow. The edges were worked as simple plaits, and I hung the edge pairs off the sides to keep them out of the way when I wasn’t using them. This only took nine pairs. This next picture is taken from the back, which is why the bobbins aren’t visible. Here you can see the worked lace, and how the whole thing is bristling with toothpicks!
As I worked, I found that I was starting to run out of fiber on some bobbins. I was prepared for this eventuality, though! As I mentioned earlier, I’d wound too many bobbins. So I had some prepared to add in to take over for those that were running out. However, I did it in a different way than usual. I took advantage of the fact that I was making a composite material: I had a little bottle of super glue ready. As a bobbin ran low, I would hang a fresh one nearby, then glue the fibers together. As soon as the glue was dry, I just cut the new fiber above the patch and the old one below. Not a way you would want to replace threads in regular lace, but a method that works well enough when the whole thing is going to be saturated with resin soon anyway! I ended up having to replace almost all the bobbins in the piece at one point or another. When I finished working the lace around the side, I finished off in the same way, by just gluing the fibers to the start of the lace.

Next, I turned the mold so the top was up and stuck toothpicks in all the points I had previously marked and plaited a center circle. I cut a long fresh strand of fiber off the spool, glued one end to the plaited edge at the starting point, and placed it along the marked path, pulling against the toothpicks to make the design. At the edge and center circle, I used a crochet hook to loop the long fiber around the plaits, and did the same at certain intersection points in the design. I placed the fiber along the entire top pattern twice.
Finally, I mixed up some room-temperature epoxy using a hardener that would give me a one-hour working time and 24 hour cure. I used a cheap paint brush to apply the epoxy first to all the lace on the side, then to the top. I paid particular attention to the plaited portions, since they were denser than the others, and I wanted to make sure they got enough resin to be fully wetted out. Then I just had to leave it all overnight and hope I would be able to get it off the mold the next day.

Friday, January 1, 2010

Just because I could, Part I

This past semester, I took the last class required for my Master’s degree. I had already taken all the other available electives, so Composites was the only one left. Composites are materials made of a reinforcement and a matrix. In general, the reinforcement is a fiber of some sort, and the matrix is a resin (not always, though). Fiberglass with polyester resins are probably the most familiar to the general public, as they are used in making boats and skis and such. As a requirement for the class, I naturally had to make something using the materials available in the plastics/composites lab. I opted for something made out of carbon fiber, rather than glass, because carbon is just cooler.

During a class period earlier in the semester, I think when we were discussing forms of cloth made from reinforcement fibers, I started joking about making composite bobbin lace. But for my actual project, I planned to make a carbon fiber laptop sleeve. Well, when it got right down to it, my joking captured my enthusiasm much more than my practical plan did, so I became determined to make a functional piece of bobbin lace out of carbon fiber. Due to the general dimness of my living room, I decided to make a hanging lamp, with a carbon fiber bobbin lace shade.

The first thing I needed to do was make a mold. I had decided to use an epoxy that cured at room temperature, so my mold would not need to withstand the pressures and temperatures of curing in an autoclave. I got a few rounds of Styrofoam and glued them together.

I just used Elmer’s all-purpose glue, and I wasn’t sure how well it would work on the polystyrene foam. Fortunately, it worked quite well for my purposes. The glued-up foam pieces were the size of the lampshade, with no cutting or shaping required. So next I needed to make the pricking for the lace.

Normally I work lace on either my broad, slightly domed cookie pillow, or my roller pillow, which is set into a broad, flat pillow that supports the bobbins while working. For this project, I would be basically working on a large bolster-type pillow, with the lace working around the entire pillow and the bobbins just hanging from the work.

Because the resin would be applied to the fiber while on the pillow, I needed to make sure the composite lace wouldn’t get stuck to the pricking. I took a sheet of release paper home from the lab—I’d used it before in some preliminary work and found that the cured epoxy peeled off the paper quite easily.

I had done some preliminary drawings on graph paper to determine the design, a basic honeycomb ground to fit the 9” width of the pillow. After cutting the release paper to a strip that would just fit around the mold, I started drawing grid lines. At first I tried using pencil, then gel pen, but neither would mark the paper. So I dug out a couple of Sharpies, red and black, and drew grid lines at one inch intervals in red.
Next, following the plan on my graph paper, I used the black marker to place the spots for the “pins”.
And, because it is a good idea anyway, and even more important on something like this, I drew in the working lines of the honeycomb ground between the dots.
I finished up the mold by cutting a circle of release paper to fit the top of the shade and drew a flower-like design, which I marked with pin dots, arrows, and numbering so that I could work the entire design with one continuous strand. (I did end up adding two more circles for support later on). This top part would not be worked in traditional bobbin-lace techniques, but rather the fiber would just be placed along the design, and smooshed together with the resin.
Next, I clipped the top and pinned it to the mold using straight pins, then pinned the honeycomb pricking around the side.

The mold was now completed and ready to be taken to the lab. I’ll stop my story for now, but I will be continuing it in two more installments!