The 2-Leg Fixed Shoulder Assembly

First step is to separate all of the parts from the sheets they were machined from, remove the tabs and flash, if any.

Left: There are 24 shoulder risers
4 shoulder plates
[8 if cut from .125 thick styrene]
and 2 .040 edge strips

Note: If you purchase only the shoulder package
your risers come on a sheet as shown. If you also
purchase the frame package then the risers are
mixed in with the other framing components.

Actual assembly starts with the shoulder plates and the shoulder risers.

Separate the shoulder plates from the panels. The .25 styrene
is rigid enough that they can be pop'd out with a little pressure.
the risers will have to be cut as the .125 styrene is flexible
and the tabs will not snap. Each panel is a pair. Don't mix them.

those little tabs are sharp and just like the knives on
a blender. cut them off right away!

The plates are symmetrical. Pick one of the slots that lines up
with one of the center bolts and mark that as "top". Also mark
inside (countersinks in center) and outside (countersinks on edge)

Turn the plates over, again mark inner/outer (it's not obvious
from this side!), "top" and the other 3 slots that line up with
the inner bolt holes.

mark the short risers, either before you cut them out or after.

Test fit the risers in the plate.
note the short risers (marked) go into the slots that line up
with the inner bolt holes (also marked).

Yes, you can put a long riser there, but it will interfere with
the bolt later on so don't mix them up  when you glue!
Left: Put a set of bolts thru the holes to make sure everything
lines up. It also helps by verifying you've got the countersinks
on the outsides!

Above: Here's an edge view of the test fit shoulder. It's a
little tight getting access but I didn't want to leave the
short risers out.
At this point you are ready to glue up the shoulders. My suggestion is to do one side at a time as follows:
Remove the nuts, but leave the bolts in place.
lift off the plate that's on top (doesn't matter if it's inner or outer).
One at a time, remove a riser, coat the mating edges of the riser with glue and re-insert in it's slot.
make sure the riser is as far to the outside of the plate as it will go. the outside edge supports the .040 wrap that goes on later.

It's ok if it sticks out a hair, you can always file it down after the glue drys.
Replace the plate you removed earlier and bolt together. Set aside till the glue drys.
remove the nuts, but leave the bolts in place.
Take off the plate to be glued.
Carefully run a bead of glue on the surface of the all of  risers that contact the plate.Work quickly as the glue will run.
Replace the plate, and bolt together. Turn the assembly over so that the plate being glued is down.
You can reach in and add glue to the area where the riser and slot meet..

Set aside till the glue drys.

Next steps will be to install the bolts, washers and nuts from both sides of the shoulders and then glue on the edge strip.
Aside: In the instructions that follow the shoulders pictured are 3-leg shoulders, but the assembly process is the same.

The shoulder risers might stick up slightly. Since you
want all of the shoulder surface in contact sand them down.

Right: I used a 1/4 sheet palm sander to sand my hubs
Below: edges are now smooth.

install a pair of washers & nuts on each edge. Start from the inside set of bolts.

If you don't have a Jr Jedi with small fingers to help
a pair of needle nose pliers can be useful.

Don't forget to use something to lock the nuts in place.
(Loctite is only a suggestion)

redo the marking for top, add a mark for bottom
add a third mark about 1/3 of the way around from
the bottom.

glue a piece of scrap styrene at the bottom point
to double the thickness where the edge joint will be

Wrap the edge strip around. It's deliberately oversize.
start in the middle of the double thick rib you just made.

glue the edge strip on up to the 1/3 point marked earlier.
put glue on both the shoulder edges and the ribs
set aside to let the glue dry.

Once the glue on the first 1/3 is dry trim the end of the
edge strip so it fits tightly. glue the remaining 2/3 of the
edge strip in place

The joint will be on the underside of the shoulder hub
and hidden behind the leg
I used a flat file to trim off the excess width on the edge.

Right: It's been suggested that foil tape makes a good finish.
Shown here is a roll of tape used for sealing HVAC

Don't want to cut your own? You can try this parts source.

The ends of the bolts will stick up slightly above the nuts. If you are using my Box Beam Legs the nuts extend into the area where the back end of the Shoulder Hub sits. To allow the Shoulder Hub to seat properly you will have to trim the back edge slightly. To reduce the amount you need to trim from the Shoulder Hub you can shorten the bolts so they are the same height as the nuts. See my notes on the Shoulder Hub page about trimming a hub.

There are lots of tools you can use to trim the nuts. I choose a dermel grinding tool.Above: Before and after trimming. Watch out for a thin edge at the top of the bolt. It can be sharp!

Left: Expect the Nut to be ground down a little. Use the same Nut, moving it from bolt to bolt. Throw it away when you are done

Whatever process you use, it will generate heat! Keep the bolt/nut cool by using a wet cloth. If it get's too hot your styrene can melt!

Congratulations, you've got a completed set of fixed shoulders for your R2!