Introduction: Pin Bed Forming Machine
Paralyzed by design nihilism in a consumer culture submerged in overabundance and disposability, how should designers continue to work? How can we embed new concepts of value through interventions in the production process to make more emotionally durable objects?
Alice Gong proposes a studio scale solution by fabricating a manual Pin Bed Forming Machine. An open-ended tool that welcomes interpretation, as negotiated by both the medium and the operator, to make objects of infinite variety in form and affordability using one setup, whether it be as one-offs, multiples of an edition, or in mass.
While a drill leaves a circular hole, a mold casts it's own positive, and a program machines one modeled part, this tool aspires to eradicate the authority of a tool's absoluteness by being an ambiguous machine.
Designed with predefined yet unpredictable parameters, it has the ability to withstand high temperates required for thermoforming knit polymers, or the liquid residue from paper pulp, to clamp down on lightweight textiles, to scorch pieces of lumber, or eventually leave rust patterns when sculpting clay.
Step 1: Inspiration
Metal pin point impression toys have the ability to absorb the relief of any object that they are pressed upon. Unlike clay or other casting materials that can only hold one shape, this toy as a tool has the potential to make a variety of positives. By replacing the free-floating pins with threaded bolts and screws this toy can be transformed into a unique process for making material samples and finish products.
Step 2: Choosing the Pin Bed Resolution (x&y)
Each "pin" is make up of a screw and a nut, with the nut being the part that presses into the material. Factors to consider when determining the resolution of the forming bed:
- Thread size of the screw
- Distance the screws are spaced apart.
The thread size dictates the thickness of the screw and thus the size of the acorn nut. Therefore the smaller the thread size the smaller the impression left on the material.
In order to cover a surface area that is 4 by 6 feet I chose to use a ¼- 20 size screws simply due to a preference for the size of its corresponding acorn nut. Originally, I wanted the grid to be of an extremely dens resolution, ultimately I chose to space the screws 1 inch apart due to budgetary and sanity reasons.
Not all these holes need to be activated all the time, having this grid of holes only dictates the maximum resolution and size of the machine workspace.
Step 3: Screw Length & Depth of Workspace (z)
The length of the screw is important because it determines the maximum depth of the relief, the longer the screw length the more clearance height there is for forming larger projects. For this first setup I purchased 4 inch screws (the longer they are the more expensive) to cover the entire surface of the bed.
However the machine is adjustable such that threaded rods and bolts of any length can be placed interspersedly throughout the grid, just like setting the number of active points in a bounding box. For example, I could place a 10 inch screw every five holes.
Step 4: Designing in Fusion 360
Four by Six feet in width and length, this sculpting machine is comprised of two pin beds that meet together like the negatives of a two-part mold. With a free hanging top layer and a threaded bottom layer, each with the capacity to hold a resolution of 3750 screws, this tool is set up as a framework to morph into any shape or pattern.
The bottom layer holds 1/4-20 phillips pan head screws. Each screw is secured through a grid of threaded holes with acorn head nuts through a sheet of 1/4 inch aluminum. On the top layer, the the same grid of screws is mirrored with bolts that are suspended freely and held in place with normal hex nuts.
Fusion is great for designing 80/20 structures, I was able to download exact parts from the 80/20 product site and model iterations of the framework. The machine had to hold a few hundred pounds in weight, so to make sure it could support itself I consulted with technicians from 80/20. *reminder* do not try to pattern array all the screws...your computer will crash.. save save save
Step 5: Working Prototype
To test that the aluminum sheet is thick enough to hold threads, and to check that the linear alignment between screws on the bottom and top layer, a small prototype was made.
The height of each screw on the bottom layer is adjusted with a power drill. As the that screw moves up the convex top of the acorn nut will push against whatever material is placed above it. If that material was a think textile, the convex tip of the acorn nut would match up with the convex hole of the partially screwed on hex nut on the bolt from the top layer. In order for the top screw to push down on the material with pressure, a compression spring is added. This way light and thin materials will not slip away.
If the material was a slab of clay, I could always attach acorn nuts to the ends of all the screws so that a small round impression would be left on the material from both sides.
I could also design and fabricate in metal or by 3D printing any custom shape attachments to replace the nut. The attachment would act like a stamp in its own right. It could be the same size as the nut, but it could also span a 4 by 4 inch area. It can be a pointed attachment or a textured surface attachment. As long as the back side has a 1/4-20 threaded insert for the screw, anything can become the pin head.
Step 6: Book Matching Pre-cut Aluminum Sheets.
The holes will be machined on the HAAS vertical mill, and since 12 by 24 is the largest size stock that can fit in the machine, thats the size I ordered.
I ordered 24 sheets of 12 by 24 inch 6061 aluminum from Coastal Aluminum. They were delivered them precut from a 4 by 12 feet sheet. Make sure to triple confirm that the size of the sheets are actually 12 by 24 (or whatever size you ordered). Although I was given a verbal confirmation that kerf of however they cut down the material would be accounted for...it was not. The sheets were all short by 1/8 inch on the long side.
6061 aluminum is not the most consistent when it comes to flatness. To prevent the pieces from warping in random directions when installed, I book matched them back to the original layout in which they were cut. Then each one was numbered an labeled. Some pieces were identified as corners and others as edges.
There are two designs, each with two setups for machining, the corner design and the edge design. In order to obtain maximum efficiency, I stacked four sheets and milled them all at once. Since they will be secured down tightly on a custom sub-plate in the machine, I clamped four sheets together to accurately measure the thickness of the stock using calipers.
Step 7: Waterjet Test
Before I made the decision to machine all the holes on the HAAS Vertical Mill, I tested another method. It turns out that Waterjet holes were not as clean and unanimously perfect as I predicted, and the processes to cut what is shown above took over two hours. Afterwards, I would still need to hand tap 12 sheets worth of holes...
Step 8: HAAS Test - Setup 1
Using the scraped waterjet sheet of aluminum, I ran a test setup on the HAAS. Always run a test on scrap material before machining the final part. For this test I did not stack any sheets together, I only machined one sheet on top of a spoiler sheet. The aluminum will be held down on a sub-plate made up of a grid of 1/4-20 holes and 1 inch holes.
For both designs, the corner sheet and the edge sheet, two setups are required for machining all the holes. In this first setup, a bit will come and peck drill a pilot hole for making a 1/4-20 thread. These 9 threaded holes will then be used to hold the material down into the sub-plate using a socket head screw during the second setup.
The aluminum sheet in setup 1 is held down using clamps. The clamps are placed around the edge of the sheet, away from where the tool will be drilling, and where the tool head will not run into them. Make sure to leave plenty of space between the 9 drill spots and the clamps. It is also important to measure the height of the clamps for the sake of defining your tool clearance height, so that the bit will not crash with your work holding.
In the first set up, the placement of these 9 holes are lined up with the 1 inch sub-plate holes, so that as the tool machines through the aluminum sheet and spoiler board with a -0.05 offset from the stock bottom, the tool will not machine into the sub-plate. Alternatively you can pre-drill slightly larger holes in the spoiler board on the drill press, this way the 9 holes can be aligned with the 1/4-20 holes in the sub-plate.
Once these 9 holes are made, BEFORE removing the clamps that are holding your materials together, tighten the sheets into the sub-plate with screws. Now remove the clamps so that here won't be anything blocking the tool head when drilling the rest of the holes.
Step 9: Setup 2
In the second Set up, select all the remaining holes for spot drilling, pilot hole drilling, and tapping. Make sure the retract and clearance height of the tool goes above the small head of the screw used to hold down your material. It was 0.03 inches in this case, 0.04 to be safe. Measure with calipers! Double and triple check that the tool will not machine where the first 9 holes are, otherwise it will machine into the screws. Check in your simulation on Fusion and on the HAAS. If you are too lazy to select all the holes when CAMing, simply make the 9 holes in the first set up a slightly smaller diameter and then check select same geometry.
Step 10: Machining the Final Parts
In order to make threads through four layers of 1/4 thick aluminum, make sure your tools are long and thin enough to reach all the way down without the tool head crashing into the top of your stock. The body of my roll tap was not long enough because the diameter of the tool got bigger near the end. The threads will be able to reach the bottom sheet if the body of the tool is smaller than the pilot hole. All I had to do was take down the diameter near the end of the tool using the manual lathe as to extend the 1/4 inch diameter part a bit further.
When it comes to machining all the final parts, load a couple of each tool into the HAAS carousel and measure each once. Once the sub-plate is attached, you will no longer be able to measure tools, so if a drill breaks you will loose that entire setup trying to load another tool.
Laser cut an alignment template for loading your sheets onto the sub-plate. Use clear acrylic so you can see the holes on the sub-plate through the alignment template. Make sure to use thick acrylic too, so that your aluminum sheets can pushed against the templet's edge.
Step 11: Welding Sheets Together
Tig Weld your machined sheets together by the short end on both sides. First remove a 1/8 chamfer along the edge using a pneumatic angle grinder. Then clean the edge with a scotch bright consumable to get rid of any impurities in the metal.
Make sure to weld the right edges together! Clamp down each sheet evenly and obsessively to prevent any warping due to added heat from the welding. Additionally, make three spot welds around the seam before laying down your beads to prevent the sheet from moving. DO NOT remove any clamps until the material has cooled off and has retracted to a stable shape.
After welding one side, flip that side down facing the table and use small pieces of welding rod as sticks under the sheet to keep it even and flat against the table before clamping. Without spacers under the pre-welded side, clamping down on the sheet will cause it to bend significantly.
Then sand blast all the welded sheets.
Step 12: Machining 80/20
The 80/20 frame that supports the top layer of screws fits together with mitered ends. The supplier could not machine these extrusions to fit the hardware required for attaching mitered ends, so following the instructions on their online catalogue, I machined the proper holes at Pier 9.
Step 13: Cutting Off Corners
The four corner sheets for the bottom layer of screws were cut down on the band saw before installation. Based on my Fusion Model, I needed to remove a small square from the corner of each sheet where the legs of the 80/20 structure are.
Step 14: Assembly
When designing the machine, take into consideration EVERY step of assembly. Do not leave any step unresolved.
All the parts fit into a CAD model seamlessly, but building in the physical space requires following a specific order of operation. I ran into a few obstacles and it took a few attempts to put all the pieces together. If I could go back I would write an instruction manual for myself to troubleshoot any problems that could come up when installing.
Step 15: More Assembly
Once the Structure is built, slide in the aluminum panels on the lower layer. Do not tighten everything fully until all the parts are lined up perfectly square.
Step 16: Installing Screws
Put on some music and screw in some screws! They don't need to go all the way through, just far enough past the sheet so that an acorn nut can be attached.
Step 17: Acorn Head
Attach all the acorn nuts. Hold the screw from underneath to make sure they threaded on all the way.
Step 18: Top Bed
Slide on the panels for the top bed and drop in all the screws. Slide on the compression springs and secure everything in place with a nut.
Step 19: Voila!
The first setup is installed and the framework of your machine is complete!
Time to experiment with materials and invite other artists to come interpret the machine!