Outcome
I designed this sanding grip to help reduce hand strain during the hours of bodywork that has to occur on a buggy before it is ready to paint. Gripping around a sanding block is necessary for adequate control, but over hours of sanding this causes your hands to cramp.
Thus, I aimed to design a sanding grip that would allow the user to have sufficient control of the sanding block by just pressing down on the block while sanding. Ideally, this grip could be removed and reattached easily so it can be used on sanding blocks with different grit paper.
Through initial drawings I quickly settled on a design that could easily be removed from or attached to a sanding block. This design simply sits on top of the sanding block and screws in with four wood screws.
However, in my drawing and ideation process I was unable to settle on a proper palm/hand grip. I drew a simple oval and a hand-shaped imprint, but in reality decided that the final grip shape would need to be somewhere in between, to allow the block to suitably conform to your hand while still fitting many different hand sizes, and even left-handed users.
As the block grip would be relatively thin, I initially debated using slicer to form a core material, but decided that shaping the clay onto a 2x4 would be sufficient support, and the use of a core material would impede my shaping the clay more than it helped.
I began by packing clay onto the 2x4 and using the rake tool to flatten it, but quickly noticed I was straying from my desired dimensions and needed a more precise tool. For this, I laser cut a piece of acrylic which I used to rake away excess clay and get it to the desired thickness (0.25in).
The next step in the process was to design the grip. Initially, I simply pushed a handprint into the clay, but when I initially gave it to another buggy mechanic to test, it didn't fit his hand size. This made it clear that I needed a less detailed hand grip, that is less specific to one person's hand size. However, the grip still needed to conform well enough to the user's hand that they wouldn't have to wrap their hand around it to use it.
Thus, I decided to determine where the points on my hand were that I applied the most pressure when sanding. To do this, I laid a sheet of paper on top of the grip, coated my hand in chalk dust, and pressed down on the block as if I was sanding.
The resulting paper showed two major patches of pink chalk, as well as a patch for each of my knuckles. Initially, I didn't want to add imprints for my knuckles as this would restrict hand size. I used a needle tool to serrate around the edges of the imprints I wanted, traced from the paper. I then used the loop tool to cut down the imprints to a comfortable depth.
After some testing sanding with these imprints, I found that the grip wasn't quite sufficient; particularly when pulling the sanding block towards the user (rather than pushing it away). Thus, I added a third imprint based on the placement of my pointer finger, once again using the needle tool to trace from the paper with chalk.
The last step in the initial shaping of the block was in adding the holes for the wood screws. I found the desired location of each of the holes with a set of calipers, then made the holes by hand with a drill bit. After making the holes, I used the potter's tool to smooth the indents, and worked on the final finish with some fine grit sandpaper.
However, through transporting the block and grip, it got dented in a few places, so I left off final surface finishing until closer to its silicone casting.
FUTURE WORK
While I am happy with the shape of the grip and its imprints, I plan to work more on the surface finish of the grip to give it a more manufactured look. In my smoothing edges and rounded corners, I made the grip look too organic; before final sanding, I plan to make the edges of the grip more crisp. In addition, my handling and testing affected the finish of the hand imprints, so I plan to work on smoothing those faces.
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