Designed by: Ethan Sobkowich, Yanshen Zhou, Winnie Lin
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Needs statement: There exists a need to create a fixture that can hold specimens in a stationary position for adhesive curing while being adjustable able to accurately create different specimen sizes. adjustability?
Constraints:
All three adhesive joints curing at the same time
Constrained movement in three axis
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The idea behind this design is to create a “tray” (Fig. 1 & 2) to constrain movement in the outer edges of the specimens. Multiple specimens can be cured at the same time in this tray. The spaces between each individual specimen will be separated with rectangular 3D printed jigs (Fig. 23 & 4) as well as the spaces between each adhesive joint on a specimen (Fig. 4). A flat board/weights will be placed on top of all specimens to add pressure.
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Steel to steel
Composite to composite
Steel to composite
go thru reasoning to do this design. decision making matrix
show dimensions and material
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Fig. 1: An image of the base tray for the testing jig
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Fig. 2: Detail drawing of the tray
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Fig. 23: An image of one rectangular jig
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Fig. 4: Detail drawing of the 30mm jig
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Fig. 5: An image of the separating jig
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Fig. 6: A detailed drawing of the separating jig
Figure 7, seen below, is a side view of one test specimen, whose material may vary depending on the test. This is how they will be aligned in the jig. The rectangular jigs will be placed in the gap spaces.
*jig can be spring with boards on either side (will remove tolerance error)
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Fig. 7: A 3D model of the specimens glued together
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Fig. 38: Side view of specimen in a tray
Figure 4 8 is an example of how the jig will clamp the test specimen. The green planks are aligned as seen in Figure 39. The main edges will be placed on a flat board or table. Then, another flat board (like a piece of plywood for example) will be placed on top of the specimens and weights will be placed on top of the board to apply downwards pressure on the z-axis (purple). When the tray is full of specimens and brown rectangular jigs, seen in Figure 49, y-axis movement will be restricted due to the packing of specimens an and jigs. A sliding board will be on the edge and a pipe clamp will apply inwards pressure on the x-axis. The idea is that the blue square-shaped pieces will ensure that the test pieces line up properly under this clamping force. It is possible that more thin brown square pieces may need to be added in the middle section to ensure adequate restriction on movement. Nine of these specimens must be lined up at once inside of this tray for proper usage.
put ALL specimen. show board above
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Fig. 49: Example of how specimen specimens will be placed in the tray. This assembly can be viewed in the GrabCAD (requires login first: https://workbench.grabcad.com/workbench/projects/gcwijX10VhtEeZ8mtyGdmiV5BQItzO7K-9PXmyIs5vRPFL#/file/559665489 )
Engineering Design Specification Chart
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Table 1: Anti-stick Solution Comparison Chart color code this
Parchment Paper | Wax Paper | Saran Wrap | PFTE Tape | |
|---|---|---|---|---|
Ease-of-use Weighting: X2 | Use sheets to cover exposed areas. Some openings will need to be taped up 7/10 | *Same as parchment paper 7/10 | Cling wrap does not need tape. Works fine 9/10 | Needs to be taped on to all exposed surfaces 6/10 |
Effectiveness Weighting: X3 | Epoxy peels off easily. 9/10 | Slightly worse than parchment paper. 8/10 | Same as parchment paper 9/10 | Epoxy needs to be chipped off of tape. Stickage may occur. 5/10 |
Affordability | 12 in X 75 ft $7.99 CAD @ Canadian Tire | 75 in $4.49 CAD @ Canadian Tire | 25 m $1.79 CAD @ Canadian Tire | ½ “ X 480” $0.79 CAD @ Canadian Tire |
Maintenance | Remove tape and paper after each use | Remove tape and paper after use | Remove wrap after each use | Can reuse multiple times |
Feasibility | Can be found in most retail/grocery stores | Can be found in most retail/grocery stores | Can be found in most retail/grocery stores | Can be found in hardware stores |
Level of Obstruction | *Reference | Thinner than Wax Paper. | Thicker than Parchment Paper. |
Results:
Parchment Paper = 41 pts, Wax Paper = 38 pts, Saran Wrap = 45 pts, PFTE Tape = 27 pts
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Source: https://www.youtube.com/watch?v=uLH1MsaHnX4
add some figs
one design matrix per step
Assembly Procedure
All related CAD files are found here (MSXIV->Devlopment->Materials Testing-> Adhesive Curing Fixture): https://workbench.grabcad.com/workbench/projects/gcwijX10VhtEeZ8mtyGdmiV5BQItzO7K-9PXmyIs5vRPFL#/folder/10457511
Step 1: Printing
The pieces separating separate individual specimens and individual components within the specimen. 3D printing was chosen as the manufacturing method as they need to be thin (<1mm) to fit under the paces of the specimen.
Use this GrabCAD file tp print the pieces:
Use PrusaSlicer to print an array of support pieces on the tray. Two of the longer spacing supports “30mm mid jig” pieces are required per specimen and 3 three of the spacing supports “separating jig” pieces are required between two specimens.
You may need to change the dimensioning of the support beams to customize it to the dimension your specimen.
Print according to the number of specimens that are cured.
Remove the printed pieces.
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Table 2: Support Component Manufacturing Decision Matrix
Machine Shop Tools | Laser Cutting | 3D Printing | |
|---|---|---|---|
Ease-of-use | 0 | +1 | +1 |
Precision | 0 | +1 | +1 |
Affordability | 0 | -1 | +1 |
Time Required | 0 | +1 | +1 |
Feasibility | 0 | -1* | +1 |
Total | Datum | +1 | +5 |
*Feasibility for laser cutting is -1 because the Rapid Prototyping Centre does not machine parts that are thin enough for this application.
Step 2: Machining Cover
This component is placed on top of all the specimens after they are placed correctly. The purpose of this cover is to restrain joints with epoxy from lifting.
Measure and mark the area to be cut on the 3mm birch plywood. Ideally, each length and width should be 0.5cm less than the inner dimensions of the tray. For example, if the inner dimensions of the tray are 19cm by 24cm, then the dimensions of the tray are cut from the plywood should be 18.5cm by 23.5cm.
Use a band saw in the design center machine shop to cut out measured dimensions.
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Use AutoCAD to create layout of pieces that need to be laser cut. In total, this needs to include 4 copies of each component of the tray. There is an AutoCAD .dwg file on the GrabCAD- use this template as a base for your dimensions. Change accordingly so the fixture can cure the desired number of specimens.
Ensure that your dimensions for the inner length and width of the tray is equal to the width of all the support pieces and the specimens.
The idea behind this is to stack four 1/8 inch thick pieces of fiberboard to create a 1/2 inch tall tray. Ensure that each part in the .dwg file is quadrupled. Please minimize space taken up by the drawing (this minimizes cost).
Minimize the area occupied by the pieces. This is because the 3D Print Centre charges per square foot.
All vector cut lines should be 0.00 units line thickness and all raster/engraving lines should be set to a minimum of 0.25 units.
Submit a laser cutting request: https://uwaterloo.ca/3d-print-centre/laser-cutting-request-form
Turnaround time is 2-3 days.
Use wood glue to bond two copies of the same part.
Apply a thin strip of wood glue along the entire piece.
Clamp down both pairs of fiberboard pieces for curing. This takes 24 hours according to the glue manufacturer instructions.
After the pairs of fiber board have fully cured, repeat steps a-b to bond the two pairs of fiberboard. This creates four stacked layers of fiberboard.
After curing, use sand paper to sand off any excess glue.
Note: it is important to cure the layers as aligned as possible to create a flat edge.
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Table 3: Curing Tray Manufacturing Decision Matrix
Machine Shop Tools | Laser Cutting | 3D Printing | |
|---|---|---|---|
Ease-of-use | 0 | +1 | +1 |
Precision | 0 | +1 | +1 |
Affordability | 0 | +1 | +1 |
Time Required | 0 | +1 | -1 |
Feasibility | 0 | +1 | +1 |
Total | Datum | +5 | +4 |
3D printing such a large part would take a significant amount of time. It is also a simpler shape, so the complex structure capabilities of the 3D printer are not required.
Step 4: Anti-stick Solution
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Item | Amount | Description of Use | Supplier | Total Price |
|---|---|---|---|---|
1/8” Fiberboard | 2 square ft. | Material for laser cutting. Creates tray. There is also an option to purchase material at the prototyping center, which is a little more expensive. | UW 3D Print Centre | $4.00 + tax |
ABS Printing Filament | 1 kg | Support material in between specimens and within specimen pieces. | Amazon (if no sufficient supply in Bay) | |
Saran Wrap | 900cmx30 cm | Prevents epoxy from curing to the fixture. | Walmart | |
3mm Birch Plywood | 20cmx30cm | Applies pressure from the top of curing fixture | E3 Machine Shop | |
Wood Glue | 236mL | For gluing the layers of laser cut fiberboard together. | Canadian Tire | |
Total cost per one fixture (CAD, includes tax) | $51.63 |
generally less walls of text. pictures explain for you, just use the right pictures.