Introduction: Light-Duty Custom Spools for ABS Plastic
Having just joined the Milwaukee Makerspace , I found a lot of interesting side-projects that needed tackling. It just so happens that I haven't done any wood-working since 10th grade, so many of these projects are experiments designed to reaffirm what I thought I knew and teach me a damned good lesson about what I never knew in the first place.
For this project, a couple of makers had some concerns about the ABS plastic filament for the Makerbot (3D printer; Cupcake version) being lightly coiled, zip-tied together, and strewn about the desk. In one instance, the filament kinked and a print got interrupted midway through.
After a brief discussion, I decided that this was worth tackling and I designed two projects: making spools for the filament and a spool holder to keep them above the desk and out of the way.
(Note: I'm including what I used here, but this is by no means the only way to do it. I used what I was familiar with and what we had on-hand.Your results may very. Consult physician before stopping project. Do not attempt on an empty stomach.Do not drive or operate other heavy machinery while attempting to drill, cut, screw, sand, or stain project. Have a nice day. Be kind, rewind. )
For this Instructable, you will need:
-A sheet of light, 1/4 inch plywood (I believe that a 2'x3' piece should work fine)
-Some narrow, heavy-duty cardboard tubing (this one came from a roll of plastic sheeting), 2 1/4" outer diameter, 1/4" thick
-JB Kwik (quick setting 2 part epoxy) AND a softer, two part epoxy. (I found that the JB Weld tacked things in place nicely, but I wanted something easier to mold so I could work it into the joints)
-A saw (I used a bandsaw here, but I suppose you could get the same result with a hand-held scroll saw)
-A disc sander (for smoothing out the plywood discs)
-A power drill (I used a drill press)
-A hole saw (Make generic, unfunny whole/hole homonym joke here)
-A compass (The exciting, circle-drawing kind, not the boring, magnetic kind)
-A beer (...As a reward for after you've finished the project. I do not condone drinking and operating power tools; this is how people end up in the ER with fence posts stapled to their face....)
Step 1: The Dimensions
Fortunately, I had a factory made spool on hand that I could measure to get the approximate size.
Remember that the center has to be hollow so that it can slide onto a dowel for use. I ran into a problem here, but more on that later.
First, get the outer dimensions of the circles for the outside of your spool. Mine came to about 8" in diameter.
Next, measure the inner diameter of your cardboard tube. Mine was 2".
A friendly tip : I find it easiest when cutting circles to place them as close to the edge of the material as I can. Not only does this cut down on waste, but it reduces cutting time by up to 1/64 of a minute or, for the metric-inclined, 1/64 of a minute.
Using your compass, set it to the outer diameter and trace 8 circles on your 1/4" plywood.
I cannot stress this enough: Always mark your center-point!
It is incredibly easy to lose that tiny dot left by the point of your compass that marks the exact center of each piece. You might not know it, but you will need it at some point (and, in fact, at several points in this Instructable). Put a nice little "X" there. Even better, you might want to consider hitting it with some fluorescent paint.
Set your compass to the interior diameter of your cardboard tube and trace another circle using that wonderfully highlighted, blacklighted, X-marks-the-spot-center-point that you so thoughtfully marked after the previous step.
Wow. You should now have donuts traced on a board. Take a step back and congratulate yourself while no one's looking.
Step 2: The Center Pieces
This is the point at which I tired of working with an abstract concept and I wanted to get some actual work done.
Take your cardboard tube and measure out 4" lengths. Mark each length carefully. This is one of the places where I screwed up.
I eyeballed the required lengths on a bandsaw. In spite of the fact that I had marked the exact lengths along the circumference, bandsaws allow for human error...a LOT of human error. Even though it felt like I was cutting at exactly the right spot, I wavered here and there and wound up with centers that were off by quite a bit.
The best thing that you can do is either invest in a compound miter saw, or talk your local Makerspace into letting you use theirs. No matter how tight your tolerances on the outer discs of your spools, if you don't cut your centers just right you'll wind up with a mess. Kids: Don't let this happen to you.
I was careful enough to measure 4", cut, then measure the next 4". This way you don't have to take into account the amount of material removed by the thickness of the blade. Unfortunately, I didn't use the miter saw to square off my ends first, resulting in a sub-par cut which threw the spools out of alignment.
I honestly don't think that it's enough to matter, given the feed-rate for Cupcake Makerbots, but who wants wonky spools? Anyone? Anyone? No? Yeah, I didn't think so.
Step 3: Prepping the Outer Discs....
I cut the outer discs on a bandsaw, knowing that I would achieve something less than perfect circular-ness. This is why god invented bolts, wingnuts, drill-presses, and circular sanding discs all on the same day.....
After seeing my horrifying freehand interpretation of circles, I realized that I could use the mid-point as a guide.
Essentially, I used a drill press and drilled down straight through the "X's" that I left as the center-points of my circles. From here, I inserted a bolt that was about the same size as the hole and added a wingnut that, when tightened, aligned all of the "circles". From here, I started making passes with the disc-sander. The trick here is to keep the piece moving, rotating against the sanding disc.
You can see the before and after shots above.
Step 4: Cutting the Inner Holes
With the wingnut and bolt removed, I was left with a perfectly centered hole that I used to align the hole saw.
Originally, I was going to have the center cardboard pieces fit through the holes so that there was a little overlap. Unfortunately, we didn't have the right sized hole saw. What we did have was one that was exactly the inner diameter of the tubes.
The small circle that I had traced for those center tubes would become my guide as it delineated the outer diameter of the tubes. I found this useful for deciding where to put the JB Kwik Weld to affix the center tubes, but more on that later. You can even see the guide line in the picture above.
Another helpful tip: When cutting plywood with a hole-saw, it is best to cut through midway, flip the piece over, then cut through from the opposite side. I was impatient (an endearing trait, I might add) and instead cut straight through from one side. The result was that as the saw cut through the final layer, it chipped the other side. Alas, my near perfect circles were dashed from their previous heights of glory by my own hand.
For those who haven't used a hole-saw before (myself being one of them), there is a drill bit in the middle. In my case, this aligned perfectly with the hole I had previously drilled.
I cut each piece individually because those saws heat up and I was mildly concerned about starting an inferno 12 inches from my face (I have a beard to look out for, after all). Additionally, I wasn't sure I could keep all of the pieces aligned through the whole process.
I used a drill-press here, but if you have a steady hand I see no reason why you couldn't use a power drill.
Step 5: Gluing Your Fingers...Uh, I Mean "The Pieces" Together
With all of the pieces cut and ready for action, I attempted the final step: affixing them to each other and not to myself, the table, or the friendly neighborhood cat that sometimes wanders by.
A few tips:
-I lined the tubes up by eye first to make sure that I had cut everything right.
-I used only a little JB Weld as I just wanted to make sure that the pieces stayed in place for the final epoxying.
-I also made careful use of some vinyl exam gloves. Some epoxies are harder to handle than others. The easiest way to apply it in this case was to get a dab on my (gloved!) finger and spread it around.
-After setting the tube in place, I pressed down and rotated it back and forth to ensure a strong bond.
-I immediately placed a weight on top to keep the pieces from escaping.
That's pretty much all there is to it. After allowing the JB Weld to cure (this stuff takes approximately 5 minutes, but I gave it an hour), I prepped the next epoxy which was much easier to apply. We had on hand several boxes of "Cytec EasyPoxy K-230 Repair Kit".
This 2 part epoxy mixes readily and is similar in texture to silicone caulk. I was able to work this into any and all crevaces where the tube and outer flanges joined. It takes 24 hours for this stuff to cure. After curing, I billed the patient 3x what I would normally charge for a case such as this, then applied some stain to either side of the wooden flanges.