Shoulder Horseshoes Assembly

Update: 09/02/20 - introduced some newer illustrations.This is the assembly process for the Shoulder Horseshoes illustrated with Ver 2.2 parts.
This is the second release of the instructions. I'm hoping the revisions help clear up any problems/questions :-(

This is a 3d model of the CS:R Shoulder - Horseshoe made from the CS:R Shoulder - Horseshoe 20140601.pdf drawing and including the Horseshoe Shim based on JAG's drawing.

The image links to a 3d pdf file, click on it if you want to be able to rotate the image around and examine it from other angles. (Note, the 3d.pdf file opens in a new window. If you have problems with the 3d feature you may have to upgrade to the latest version of Adobe Reader).

After 'activating' the 3d mode by clicking on the display
select a part by left clicking on it (the part will be highlighted)
then right clicking brings up a window.  Follow the sequence
-> part options -> part render mode -> transparent
to make the outer parts transparent and the inner
details visible.

These are the Shoulder.Horseshoe.188 panels. The two Horseshoes are mirror image. One will be labeled left, the other right. The designation is somewhat arbitrary since some builders prefer buttons mounted toward the front and some prefer buttons mounted to the rear. The parts are in different places on the 2 panels. The important thing is do not mix the parts between left and right!!

The first thing you should do is use a marker to label the parts in the panel by both their Left/Right designation and their assembly Layer. For example - L1/L2/L4/L5 for the left hand part set and R1/R2/R4/R5 for the right hand set- as above.
Only remove one set of parts from their panels at a time to avoid confusing Left and Right parts.

The .188 parts have a .05 deep edge cut into them so that when they are assembled there is a .1 deep channel between the layers.
The .188 parts are assembled as pairs - L1 & L2 and L4 & L5 with the cut edges facing each other. During assembly make sure you have the correct part surfaces facing each other BEFORE you start gluing them.
This is the Shoulder.Horseshoe.125 panel. There are two sets of both Layer 3 and Shim parts on this panel.

Because there is no edge on the .125 panel parts they are the same for both the Left and Right Horseshoes. If necessary, turn the L3/R3 part over so the voids match the rest of the assembly. (see below)
The assembly sequence is the same for both the Left and the Right Horseshoes.  Layer 1 on top to Layer 5 on bottom.

It's Illustrated on the right using the Left Horseshoe parts. Just remember that the cut edges of the L1/L2 and L4/L5 pairs of parts face each other. 
That image links to a larger version where it's easier to see the details.

This is the Shoulder.Horseshoe.040 panel. It has parts for both sets of horseshoes. The lower part is the outside edge strip.The upper row of parts on the left are the liners for the boxes. On the right are box bottom parts to make the depth of the boxes closer to the drawing standard. The Wedge top part (hole off center) covers the wedge.

It's not your imagination This last piece is used to cover the surface of the 3D printed wedge. The hole is offset.

Assembling the Layers
Begin  with Layers #1 & 2 - make sure the channel is in the center and the cutouts in the parts line up.

I've used spring clips (aka binder clips) - C-clamps might have been a better choice.

Left: Make sure the corners line up. Once the alignment is OK use Weldon #3 cement to join the parts.
The hole above is a glue point - try not to overfill it.
Once the cement on the first 2 layers has set, add layer 3.
This is  what happens when you get sloppy with the cement! It's hard to see, but the red V's point to places where the cement got under the spring clips and caused the plastic to melt. -  If it happens to you be sure to sand down the ridges!
Right: I've added the Nutserts to layer #4 - that part will be supplied with the Nutserts installed unless you ask me to leave them out.
Left: you'll need lots of clamps to hold both the inside and outside layers together.
Above, Left & Below: Alignment of the layers where the points come together is critical because of the visibility. Because of the channels cut into the parts it's not possible to trim them back without reducing the channel depth.
Lining the Boxes

One of the drawbacks to using multiple layers for the construction of the horseshoes is that the layer joints are visible and difficult to cover up during the finishing/painting process. My solution is to glue small pieces of .040 to the inside of the boxes (cutouts) as well as to the outer edge, 

there are sets of parts for all 3 of the cutouts. note that for the square cutouts the pieces are two different lengths - two slightly longer than the other two. All of the pieces are oversize in height and will be trimmed down after they are glued in place.
Left: If you haven't glued thin .040 stock now is the time to try with some scrap pieces. Cut some pieces from the scrap.
And see what happens when you apply cement.
Below - The corners of the cutouts are slightly rounded.  Use a file with a 'dead' edge (no teeth - so it only removes material in one direction) to sharpen up the corners After just a little filing!
Left: test fit the pieces. For the sq cutouts start with the longer pieces. Sand the end down (if necessary) until the piece just fits.
Clamp the pieces in place and apply cement. Note the bottle with the hypo needle. Repeat the process for all of the cutout edges.
I'm using a large coarse file to remove the edges of the box liners that stick up above the edge of the cutouts. When filing hold the file almost flat to the surface so the finished edge is square to the surface.

Not my best work, but this is the bottom of the cutout and won't be visible.

With the Top & Bottom edges of the cutout filed level it's time to attach Layer 5 to the bottom of the Horseshoe.
Above & Right: as with the other layers, alignment is critical! Once you put the cement on it's too late!
Gluing on the Outer Skin
Gently File down any high spots -  be careful not to put a flat spot on the edges. Right -  place thin cardboard spacers on the underside - tape in place.

Start at the bottom edge. Extend the strip over the end.

The spacers enable ~equal edge overlap on both top & bottom.

Clamp Down the other end. Make sure it also extends over the end. Make sure skin is tight on the curved section - Apply cement.
With 20/20 hindsight I should have taken out the bigger clamps and used them on the curve when I glued the first time. In any case if there are sections that are not tight clamp & glue again!
As a result of the layer structure at this point the cutouts are too deep. The spec calls for .65 in depth.
The layering (3x .1875 + .125) results in a depth of .6875
which is .0375 too deep.
I've provided .040 pieces to bring the depth closer to spec.
Their use is optional.

The 3D printed Wedge has been adjusted so that it's finished height, including the .040 surface layer brings it to spec height.
Trimming the Edges of the Skin

work very slowly, with the file held almost level, and only pushing against the horseshoe, file down the edge of the skin.
Check the remaining edge with your finger after every few strokes. Work your way around the horseshoe.
Repeat the process for the edge on the reverse side.

This shows the outer edge trimmed before the bottom trim is added (below) - or you can wait until after the bottom trim is in place.
Left: There's a pair of Bottom Skin .040 pieces that have a notched end to match the notches in the horseshoe. These cover the layering on the bottom edges. Since it's just about impossible to clamp these in place, rely on masking tape (add more to hold all 4 edges). Use a glue bottle with a hypo needle to put drops of glue on the overhanging edges.

Above: the 3d printed wedge's surface is quite rough. while it can be sanded smooth it's easier to glue a piece of .040 on top

Right: like the other pieces of .040 the wedge edges will have to be sanded to fit the cutout.

The wedge is square - there are 4 ways to put it in the cutout. 3 are WRONG! Make sure the wide part of the wedge is at the bottom of the cutout.
Assembled Horseshoe - ready for finishing

Thanks to R2 Builder David Codding, here's a picture of my Shoulder Horseshoe with 3D printed Shoulder Hydraulics, Shoulder Buttons and Shoulder Hub installed!

You can find those parts on my 3D printed parts page: