Tracking Antenna Base Plate Redesign

Task Description

Right now, the way the tracking antenna’s base plate is attached to the motor is kind of unstable and wobbly. We want someway to prevent the wobbling and have the base plate level (e.g., not at an angle). The base plate rotates with the motor, so the stabilizers/stands shouldn’t cause any friction.

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Task Progression/Updates

Author: @Agapa Goombs Sep 26, 2024

Design #1:

Bearing Posts:

• Based on the above, suggestions the following post was modelled:

  • Uses a 3D printed main body with 30X30 M3 clearance holes to mount onto the bottom plate.

  • Bearing Dimensions: 10mm OD 5mm ID 4mm W

  • These posts would be oriented at 90 degrees from each other

  • The bearing is fixed using a pin with body clips to secure the pin itself on either side.

Open

Design 1: Bearing Posts

Plate Modifications

• Due to the issues with the lack of available space to mount the posts on the existing bottom plate, the issues posed by the square plates and the bolt clearance, the following plates were modelled:

Open

Design #1: Top Plate

• They use the existing bolt patterns with added 30X30mm holes oriented 90 degrees from each other, allowing the posts to fix the top plate in a plane.

  • Dimensions: 400mm diameter → This is larger than ideal, but it avoids the new hole patterns interfering with the existing ones.

  • Thickness: same as before at 1/8 inch (3.175mm)

Concept Assembly:

Design 2:

• To address the large plate size of 400mm being too big for the waterjet, the top and bottom plate diameter was reduced to 280mm as shown below:

• The M3 hole pattern was also reduced to accommodate the smaller size, according to the orders of the 7X3 pattern.

• As a result, the Gemini case, which usually would be mounted on the side with the 7X4 pattern, could no longer fit. To address this, a sheet metal plate was introduced to mount the case over the centre of the top plate (slightly raised by 10mm using Jogs to avoid the gear shaft hub and its screws), as shown below:

The Gemini case’s height was also reduced from 40mm → 30mm to allow for more clearance to the bottom of the antenna. Its mounting screw pattern was updated to the 30.5 mm grid:

The result was the following assembly:

Concerns with Design #2:

• The vertical clearance between the top of the Gemini Case (41.5mm) and the bottom of the Main Antenna Assembly (48.47mm)→ about 7mm. This is with the Gemini Case’s height being reduced by 10mm.

• We need to double-check the reasoning behind the case's original dimensions based on the board to see if they can be reduced.

• The footprint of the sheet metal plate could be reduced → The width slightly overlaps with the sheet metal mounts for the main assembly but would be on top of them → There is no interference, but it would create more issues in assembly.

Author: @Sohee Yoon Oct 1, 2024

Design Review:

• Thank you for changing the mounting pattern for all the parts! Overall, amazing changes and progress on the tracking antenna!

• I agree with Smile that we should use standoffs instead of a new aluminum plate

  • It might also be difficult to bend the metal like that (bc of the small amount of material in the height)

• Smile mentions the columns w/ the bearings might be too thick so possibly reducing the thickness (currently one side is 7 mm → 4 mm)

• I saw that in the link to the bearings, there’s also a shaft (prob wanna choose the 50 mm long [shortest] one)

  • Depending on how we 3D print the hole for the shaft, we might not need a cap on both ends, but if we did, we prob want to 3D print or tape the ends tbh

  • Link to bearings for reference: https://www.servocity.com/5mm-id-x-10mm-od-non-flanged-ball-bearing-2-pack/

• On Solidworks it’s great that you measured the distance between the bottom plate and top plate! But in reality I’m guessing it might not be exactly the same. So when we end up manufacturing the changes, we prob want to 3D print the columns last, just in case we need to change the height slightly (if that makes sense)

• Looking back at some old images on discord, it looks like there are wires that come out of the middle so we do want the standoffs to have some height

  • Because of this, could we just mount the battery on the Gemini case with velcro and get rid of the battery stand? We will still be restricted by height because of the angle limiters but not as much as before. Unless the battery stand was used for support near the bottom

Author: @Agapa Goombs Oct 10, 2024

Integrated Assembly:

Notes:

• As shown below, standoffs for the Gemini Case Mount were added, with a 7.5mm clearance to the bottom of the battery mount.

• Allows for wire clearance through the middle shaft.

• Holes of the bottom plate were adjusted to allow the centre shaft to be concentric with the top plate.