Spatular Sticky Pads

The main idea with this design is to build upon the success of Sangbae's angled stalks with angled tips by both increasing the contact area and providing a sharper tip at the edge of the contact area. The shape of the stalk is created by:

• Starting with an angled cylinder to provide the angled stalk.
• Stacking an inverted cone (at a different angle) on top of the cylinder.
• Slicing that cone at the desired tip angle to create the contact area.

• Single Spatular Tip

Macroscopic Version

The scale of this design is roughly the same as the current anisotropic patches, with stalk diameters of ~380um and feature density of ~3.2/mm^2.

• Small Array of Macro-scale Spatulae

Microscopic Version

Given that Mark will be in Pisa, where they have a KERN machine capable of machining features on the 10-100um scale, there is also a version with stalk diameters of ~100um with feature density of 8/mm^2

Both Unigraphics and Solidworks balked at dealing with so many features (14,000 stalks for a mold large enough to mold 4 toes), so all of the following files have a single row of stalks and grooves.

MARK: If the guys in Pisa are able to do this for us, the toolpaths generated from these files need to be duplicated 35 times, with spacing of 1mm (it should be obvious which direction the array extends). Additionally, because the stalks are so short, in order to keep the proportions the grooves are rather deep relative to the thickness of the mold material; we may need to use something relatively stiff and strong. Perhaps steel or another metal will be better than delrin or other plastics. There are two versions of a mold which, when cast, will result in the same part.

• Version 1 is with my macroscale machining process in mind: machine the stalks, then the cones for the spatulae, then the grooves. This results in some extra features where the cone cuts part of the goove not relevant for the actual feature.

• Version 2 is more geared for a contour mill operation: it doesn't cut a full cone to make the spatulae, so there are less useless faces/areas to mill.

-- BarrettHeyneman - 19 Jun 2006