Fixed 3-Leg Shoulders
My Fixed 3-Leg Shoulders (formerly called Shoulder Hubs) are
and slot conversion of Dave
plans. The Shoulders have been re-designed to incorporate countersunk
bolt holes. For reference, the original design can be found
means that there's a set of parts for the left side
Shoulder and a set of parts for the right side Shoulder. Each set has
been marked so you can tell them apart. Since the bolt holes are
countersunk it's easy to tell the outsides from the insides. As with
design, make sure you put locktite on the bolts before the final 1mm
styrene wrap goes on.
||This is the
shoulder hub before the outer skin is applied
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).
The shoulder hubs are meant to be cut out of .25 styrene but can also
be cut from two sheets of .125 which are then glued together. If you do
that you'll have to cut the countersink holes after the parts are glued.
Hub Hardware: Just a short note. Not shown above are the 1/4-20 flat
head machine screws and mating nuts/bolts. You'll see those in the
assembly instructions. The machine screws should be 2 1/4 in. long.
That's long enough to go thru the hub assembly and stick out far
enough to bolt onto a 1/4 in. plate (either in the frame or the leg).
The problem is that most local suppliers (Lowe's or Home Depot) only
carry 2 1/2 in. and then only in the 2-3/package plastic bags. You'll
need 16 of them and it is a lot of work to cut them down to size. [Observation: buy your washers & nuts by the box from a local
supplier. It's handy to have extras so you don't have to look like a
Jawa turning your droid upside down and shaking him to retrieve the nut
you dropped into the leg! ] I
found one Internet supplier who stocks the 2 1/4 in. length and doesn't
require you to buy a box of 100. So, if you are ordering other hardware
you can spread the shipping costs over other projects. Bolt Depot might be cheaper even
with the shipping cost. The
bolt heads that stick out into the leg will need to be ground down so
that they are flush with the bolts. See the notes in the assembly
The design drawings are available
as both Autocad .dwg files and Adobe .pdf files download drawing files with the understanding that the
drawings are copyright to Media-Conversions and are not to be used
commercially. (That note also appears on each of the drawings). I've
also put together a set of assembly
instructions to help you
put the shoulder hubs together. Don't want to
cut your own? You can try this parts source.