Attaching Ribs to the Spine & Sternum

Note: You'll notice a difference between the texture and finish of the wood used in many of the images throughout the remainder of this project. I was building two of these identical props at once, and was not performing the exact same detail work (sanding and routering) on both projects.

It's time to cut more plastic tubing to create the ribs. I made this prop with four sets of ribs on either side of the sternum, plus two pieces of tubing for the collar bones/clavicles (which we'll add later after connecting the shoulder blades and arms). I usually pyramid or reverse taper them- starting in tighter and shorter at the top- then widening out and arcing up the further you go down the body. This reverse taper resembles the human anatomy. Of course you can always alter the anatomy in whatever creative way seems fitting. Remember, these guys have been buried for years- so who knows what kind of twisted wrecks they will appear as when it comes time to break out!

Here are my measurements for this prop's ribs (per individual rib per side). They appear to be in good proportion to the skull and arms that I purchased from Anatomical Chart Company:

Top Rib= 12.5 inches

Second Rib= 14.25 inches

Third Rib= 15.75 inches

Fourth Rib= 16 inches

After cutting and shaping the tubing into positions that resemble ribs, I drill holes into the ends (on the inside of the tubing- about a half inch from the edge) that I plan to attach to the sternum. I use a 3/32 of an inch drill bit for creating these holes, but you can use a bit that's smaller or larger depending on what you have access to. I wouldn't go any larger than about a 3/16 of an inch bit though, as it will start to create holes that may be too large for securing the ribs without allowing too much play.

I also drill holes into the sternum using the 3/32 of an inch bit in the positions where the ribs will join up with it. This can be done in a number of ways, but basically I drill through the side of the sternum tubing at an angle that will produce an exit hole toward the floor. I do this on either side of the sternum. So, the sternum (at this point in our project) has 4 holes in it- two on either side per corresponding rib for our set of the first two ribs. I drill the holes in the sternum and ribs in this manner to be able to conceal the wire I will be using to attach the ribs and sternum together. This first set of holes are drilled about two inches down the tubing from the point where the sternum and spine attach. This is all personal preference though. You can space your ribs at whatever intervals you choose. I stuck with a 1.5 to 2 inch spacing between the remainder of the ribs all the way down the sternum. You may want to start your ribs higher up on the sternum than the two inch measurement I used. This will prevent you from having to add collar bones/clavicles later on to fill in the space.

Now I don't attach the ribs to the sternum yet. I attach to the back of the spine first. It's just easier to pre-drill the holes, in the previous step, prior to attaching the tubing to the sternum. In this step, I attach the ribs to the back of the 2 X 4 spine with my 2 inch drywall screws and using more Gorilla Glue, as seen in the corresponding image. You can attach one rib at a time to the spine and then attach that rib to the sternum or you can attach both to the spine and then to the sternum- it really doesn't make a difference.

After securing both of the ribs to the spine, I then check the flexibility of my tubing with a few more bends. After making sure it's ready to be bent towards the sternum (again trying to prevent as many crimps as possible) I cut my wire to length. I use bar tie wire with the ends/loops straightened out or snipped off depending on the length I need. I then run it through the holes I drilled in the sternum and rib, bringing it out into a U shape.

Each rib has it's own individual U shaped wire to attach it to the sternum. I use gloves to start twisting the wire, then I bring out the handy needle nosed pliers to finish the job. I twist until the majority of slack is out of the wire and the rib is making a tight bond with the sternum. Once this is accomplished you may have to trim or twist off the remaining slack of the wire. You will be left with a tight, compact piece of bar tie wire that can be concealed by pushing it up against the inside of the ribcage.

After attaching your first set of ribs, you'll notice that they are very tight against the sternum, yet they may not be quite flush with it- we'll fix that shortly. After finishing this first set you can go ahead and continue the same process all the way down the sternum. Spacing and rib length is up to you, but again if you want to follow my measurements (mentioned in the above steps) then give it a shot- they do seem to work fairly well with the dimensions of the standard 4th quality bucky body parts.