This page will be updated with the newest information about the design of our vacuum table.
A makeshift board used to test the O-ring theory using a handheld vacuum pump. We decided to test the O-ring using a handheld vacuum pump instead of the vacuum we used for our "air-hockey" bed. The reasoning behind using an O-ring was to create an air-tight seal and thus not needing to draw large continuous streams of air. First we tried using it on the MDF plate (iteration 9) and this didn't work. We saw this was due to the fact that MDF is not air-tight. We fact-checked this by trying to vacuum grip a MEF plate without the silicon protection we have on our plate, and it wasn't able to maintain a pressure. We then quickly crafted a makeshift bed out of metal, as metal is air-tight, and drilled a hole. This was tested on many different materials and with many different size O-rings, and the conclusion was that we had to have quite a large O-ring for it to have any effect. We then moved on to testing on our frozen ham slices and this did not give good results. On the smaller O-ring, the pump did not manage to grip at all. On the larger O-ring, which is already borderline too big, it managed to grip after pumping for quite some time, and the it deformed the slice, by dragging it down. There are several reasons why it didn't work. The O-ring could be of the wrong type. |
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We started experimenting the O-ring solution by lasercutting a board that would suit many O-rings. The different sizes of O-rings could then be tested and compared. During testing with the different O-ring sizes, it was found that the bigger O-rings gave much better gripping force to the fake prostate-slice made in MDF-wood (plain surface). Meanwhile, while only using the smallest o-ring, the gripping force was almost non-existent, and the MDF-prostate was only sliding around. If this is the same case for frozen ham-slices will need to be tested further. |
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Iteration 8 was tested and proved successful. We have concluded that this subsystem is still the least optimal of our POC and should be further developed. All of this is described in our weekly log for week 43. |
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As iteration 7 proved to have less airflow we decided to increase the tubing to 11mm internal diameter. This held up good in initial testing. It has now been mounted on the CNC and will be used in ham-testing. If this model proves successful, we can leave it be until further design improvements are needed. On this model the special specs are:
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We measured how the testing-prototypes would fit on the machine and noticed that the white bed crashed with the aluminum profiles. This forces us to refine the design. In this iteration we started with design for the limits, and then removing what we could. From what we could tell, the magnets will sit nicely in the current design. We choose not to spend time shortening the bed until we see how much of an issue the length of the bed actually is. Based on initial testing of the newest prototype, a few things comes to light.
We also tried improving the lid in this iteration. There were fewer, bigger holes in a circular pattern in order to maximize coverage. The test on whether this improved the gripping force was inconclusive. |
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Two versions of the 6th iteration was printed for testing. One possible improvement to the bed could be making it shorter. We only made it that long because that was the length of the original bed, but a shorter bed would make the user interaction easier. |
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The first used a tube with:
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The second used a tube with:
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The testINTRODUCTIONThe vacuum-capabilities of both tube-diameters were tested. They were hooked up to the small, handheld pump and tested one at a time. The test consisted of seeing how well it could hold a piece of MDF. The lid was sealed with a thin layer of silicone glued to it. A Clamp was used to hold the lid in place as the magnet is not yet incorporated. RESULTSThe first test was of the white (18 mm internal) bed. The MDF was held firmly in place in the bed. The vacuum was strong enough even when only 1/4 of the holes were covered. The second test was of the black(12 mm internal) bed. There was no noticeable difference between the black and white bed. CONCLUSIONThe face that the results were the same leads me to believe that a smaller tubing can work as well, which would be easier to incorporate into our existing design. The testing will continue on Friday with a more optimized lid.
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As the design of the bed was close to finished, we chose to 3D print the entire thing to make it a bit more smooth. We have not yet decided the hole diameter of the vacuum tubing, this is just one of the possibilities. |
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The box itself is generated on Boxes Py, and is a TrayLayout. Our current layout is shown on the right. All designs are moved into fusion to add the screw holes. The holes are placed on two of the long sides:
Other settings:
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,> 10.00mm |
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The box itself is generated on Boxes Py, and is a TrayLayout. Our current layout is shown on the right. The holes are placed on two of the long sides:
Other settings:
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,> 10.00mm |
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The box itself is generated on Boxes Py, and is a TrayLayout. Our current layout is shown on the right. The holes are placed on two of the long sides:
Other settings:
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,> 50.00mm |
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The box itself is generated on Boxes Py, and is a TrayLayout. Our current layout is shown on the right. The holes are placed on two of the long sides:
Other settings:
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,> 50.00mm |
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The box itself is generated on Boxes Py, and is a TrayLayout. Our current layout is shown on the right. Other settings:
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,> 50.00mm |