Big Project | Project | Project Manager |
|---|---|---|
Antenna Tracker | Aluminum Yaw Servo Mount |
Task Description
We need to design a yaw servo mount made out of aluminum to maintain structural integrity and rotate the Antenna Tracker along the yaw axis.
Constraints
Constraints | Written By | Append Date |
|---|---|---|
Made out of aluminum (0.064in for bent aluminum) |
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Machinable |
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Utilizes Countersunk Holes for Tripod Interference (Ensure Screw Head and Baseplate thickness is adequate) OR Utilizes tapped holes in baseplate (Ensure screw length is adequate) |
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Adheres to Servo Gearbox Dimensions |
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Assignees
Assignee | Asana Task | Date |
|---|---|---|
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Task Progression/Updates
Author: Arjun Mandair Date:
First Design Without Height Adjustment Mechanism Integration
Height adjustment mechanism incomplete
Currently compatible with Tripod
Cutouts on L-Brackets are for screw clearance
Author: Arjun Mandair Date:
May need to Redesign
Depending on if we need two antenna trackers, we may need a new yaw servo mount, since we only have one discontinued servo with a compatible gearbox
Author: Arjun Mandair Date:
Countersunk or counterbore holes
Currently, the yaw-axis servo is experiencing stabilization issues, since the bolts are too far out from the servo. This was placed initially due to interference from the tripod. For the next iteration, we will utilize counterbore/countersink holes, and a bigger baseplate, to bring the bolts closer.
Essentially, bring the current holes in, thicken the aluminum plate if needed, add the counterbore holes, and good to go! You can also tap the holes and have small screws run through.
Author: Justin Liu Date
Modified the design in Figure 3 so that the mounts can now take another bolt to increase stability (bolts now make a triangle)
The mount need to be re-manufactured because there are new material added.
The mount on the left is also modified, and it also needs to be re-manufactured because new material are added.
Both modifications are made because the previous design don’t have much room to work with in terms of drilling more screw holes on the already made part to make the servo more stable.
This design can be found in the folder under dir: C:\WARG_CAD\COMP2024\Antenna Tracker\Yaw-And-Pitch Antenna Tracker\ANTENNA_TRACKER_06_SERVO_MOUNT\ANTENNA_TRACKER_SERVO_MOUNT_STABILIZATION_MOD_07MAR2024
The aluminium sheets in this design are the same as in the previous, (because I have not seem the actual thing in person so I don’t know whether I should thicken it.)
Note: please don’t roll forward the design when opening the assembly file
Author: Arjun Mandair Date
Review 1:
Hey Justin Liu , Thanks for the help! Took a look at the assembly and seems to be some confusion. We are essentially trying to bring in the alum_bend_mounts. Right now they are shearing as the mechanism turns due to the length. Bringing in these parts will lessen the shear the aluminum parts will experience. Currently, you have utilized the holes within the tripod, but the plan is to make new holes, where countersinks can fit. Essentially, we need to:
Increase thickness of the plate
Fit countersunk holes into the plate
redesign the aluminum bends to accommodate for this.
I have attached a picture / drawing for reference. Please feel free ask questions! Great work so far, and I appreciate the help!
Author Justin Liu Date:
Second modification
Appreciate the useful feedback Arjun!
Based on feedback and clarification, I created 2 configuration of the Al bend mount (the U-Bend and L-Bend)
I thickened the aluminium bend mounts to 1/8 inch = 0.125”. (Later I learned we can’t bend Al sheets thicker than 14 gauges = 0.064 inch so it won’t work, changing it back in the next iteration)
I thickened the base plate from 1/8 inch to 1/4 inch thinking that would give room to place counterbore. In this case, the entire base plate need to be re-made because it requires thicker material.
I placed the counterbore (M5) on the back side of the base plate.
Author Justin Liu Date:
Third Modification
Based on feedback, made changes on the previous modification. Again, Thank you Arjun, appreciate the feedback!!
Changes made:
Switched sheet metal back from 1/8 inch to 14 gauges.
Changed Holes on base plate from counterbored to countersunk, moved it to the mount(s) itself. (the base plate is 1/4 inch thick).
Files are in the same location as previously made (the 08MAR2024 folder)
An exploration of ways the bolt can be placed
Purpose: to see if M5 countersunk hole can fit on 14 gauge Aluminium sheet or 1/8 inch base plate.
on 14 gauge sheet: cannot be fully chamfered (14 gauge sheet < 3.18 mm countersink) (according to SolidWorks auto/default M5 countersink size), but can be partially chamfered like image Above.
1/8 inch plate: Yes it fits, can be fully chamfered
Just ideas: can try tapping the base plate and bolt the mount like figure below with or without a washer.
Or maybe they can look like this, though I don’t know if this can be (easily) machined.
Author: Arjun Mandair Date
Review 2:
Hey Justin Liu , Thanks for the help! Looks a lot better and appreciate the time it took to make these changes! Took a look at the assembly and still seems to be some confusion however. No worries! I have listed some comments below:
You have the right idea, however, imagine your implementation but flipped. Essentially, the counterbore cutout should be in the aluminum baseplate, where the screw’s end will be facing up. With the current implementation you have, there is no reason to even have counterbore holes in the first place. We need the counterbore holes to maneuver around the tripod interference. I have included a drawing below for reference.
Your method works, provided that there is a screw small enough in length where we can tap into the baseplate and not have tripod interference & there are no counterbore holes. No need for counterbores here if we go with this method. I have provided a drawing below.
Please feel free ask questions! Great work so far, and I appreciate the help!
Also great drawings and pictures! Pictures and drawings are worth a thousand words in Mechanical Engineering, so great work!
Author Justin Liu Date:
Fourth Modification
Hey Arjun, I think I got it this time! I really should’ve thought of this myself: the screw interference, the counterbore holes. Really thank you for the patient explanations, it’s huge contribution to my learning; really appreciated. Here’s the quick modification.
Change made:
countersink hole now go on the back of the baseplate instead of on the sheet metal mount(s)
(By visual intuition, using a longer screw and bolting the mounts with a nut can be considered as I feel insecure with just tapping the sheet metal mounts, however, this should be an easy implementation)
Let me know more! Thanks!!
Author: Alison Thompson Date:
CAD Review:
I like the green version, but I think the thickness of the baseplate can be knocked back down a decent bit, you do need to be thicker than the bolt head plus a bit, but not this thick. Otherwise looks good to me.
Author: Arjun Mandair Date:
CAD Review 3:
Hey Justin Liu , Please take a look at the feedback Alison provided in the confluence documentation. After this, and seeking another confirmation from Alison, you may:
Create the DXF Files
Edit the main assembly with your design
There is also one other thing I should mention (apologies for not doing this earlier). We have received dimensions for the servo gearbox as well. Please ensure your servo mount adheres to these dimensions (Note these dimensions are in inches). You may have to edit the C:\WARG_CAD\COMP2024\Antenna Tracker\Yaw-And-Pitch Antenna Tracker\ANTENNA_TRACKER_02_SERVO_GEARBOX Assembly to do this. Great work so far! We're almost complete!
Author Justin Liu Date
Editing the Main Assembly
Based on dimensions Arjun provided, the servo gearbox container was modified (updated dimensions) to fit the new aluminium bend mounts.
There are ambiguous dimensions in the manufacturer’s dimensions; the figure below shows uses “(GUESSED)” to indicate the unknown dimensions which can be changed later.
Due to the slight changes in dimensions, the mount is made slightly wider (from 35 mm to 40 mm wide) to adapt the increase of horizonal distance between left and right (AKA the 1.061 inch).
Side note: The countersink holes position on the baseplate are constrained to the aluminium bend mounts.
Drawing of the plate with countersink holes and DXF of the new bend mounts are created, located under:
C:\WARG_CAD\COMP2024\Antenna Tracker\Yaw-And-Pitch Antenna Tracker\Drawings and DXFs
Files are called:
ANTENNA_TRACKER_SERVO_MOUNT_01_BASEPLATE.SLDDRW
ANTENNA_TRACKER_SERVO_MOUNT_01_BASEPLATE.PDF
Flat pattern - ANTENNA_TRACKER_SERVO_MOUNT_03_STAND_EDIT.DXF
Only one DXF was created because the mirror of the mount is the same as bending the plat layout to the opposite side.
replaced the old mounts in main assembly with new ones:
Author: Arjun Mandair Date
Servo Backholder Redesign for Waterjet:
Hey Alison Thompson,
I modified to be compatible with waterjet. Utilized 1/2in alum 6061 plate. Not too sure about the fillets. Any thoughts or concerns? You can check out in C:\WARG_CAD\COMP2024\Antenna Tracker\Yaw-And-Pitch Antenna Tracker\ANTENNA_TRACKER_00_MAIN_ASSEMBLY.
Author: Alison Thompson Date
CAD Review:
I think the thickness of the stock can probably be brought back from 1/2” to 3/8” and the thickness of the profile can be knocked down to 1/8”. Maybe could make the fillets smaller but that doesn’t matter much, good job not putting fillets in the corners that interact with the servo. I’d also suggest you double check with the machinist on tolerancing for the waterjet so you’re sure the servo will fit in irl incase the part comes out oversized.
Author: Arjun Mandair Date
Servo Backholder Redesign Decrease in Thickness and Profile:
Hey Alison Thompson, the following changes have been made:
Changed thickness of the stock from 1/2in - 3/8in
Brought down profile to 1/8in
Wasn’t asked to do so, but I changed the M5 bolt from the backholder mount to the baseplate to M4. Please let me know if I should change this!
Double checked Justin Liu's changed in the gearbox dimensions. Seems good to me!
Rebuilt broken sub-assemblies. Fixed!
Spacing for servo gearbox = 34mm (gearbox thickness) + 0.01in (total) (aka +0.005in on each side)
I also spoke to machinist, and the waterjet is +-0.005 (which is why I increased servo cutout spacing to 0.01in total). Once approved I will order the sheet metal and screws.
Nathan and I also discussed and tested. We can confirm that all gearbox components utilize 6-32 Screws! Unfortunately, Servocity discontinued these products, so documentation is unreachable. This include the following:
Servo Gearbox
Spacer
Clamp
Author: Arjun Mandair Date:
Servo Mount CAD Review 4:
Hey Justin Liu , after today’s WARG Mechanical meeting 2024-03-19 Mechanical Meeting Minutes, we discussed the following improvements for your drawings:
Dimension the hole callout for the countersinks. Ensure they follow GD&T standards
Include a section view of for the drawing. In my opinion, the section view would look best if you section the first countersinks you see from the front (included drawing below to clarify this)
Isometric view is not needed, so please remove it
Again, great work so far! We are currently awaiting Alison Thompson approval for next steps! Thanks for the help! Preferably, please try to get this done by @ 12:00am.
Author Justin Liu Date
Updated drawing, created pdf placed in the same folder as previous drawing, pdf file is named ANTENNA_TRACKER_SERVO_MOUNT_01_BASEPLATE_REV2.pdf
Not quite sure how this base plate will be manufactured, if it is going on a CNC then I don’t know if any dimensions of hole locations are needed.
Author: Alison Thompson Date:
For Arjun Mandair 's changes:
“Wasn’t asked to do so, but I changed the M5 bolt from the backholder mount to the baseplate to M4. Please let me know if I should change this!” Unless there is a reason it need to be M4 due to COTS components (which I don’t think is the case), according to CAD guidelines, all WARG parts/assemblies should use M5 or M3 bolts only
If you made both of the thickness changes and adjusted tolerances as discussed, should be good. PDM is broken for me atm but I’m happy to approve the manufacturing of the “servo backholder” if those are the only changes
For Justin Liu 's drawing:
Overall looks good, a few notes:
I would move both dimensions of your detail view to the same side of the part
Make the thickness of the material a reference dimension because it’s not changing but is useful
Your section view scale looks to be the same scale as your main drawing but is labelled as a different scale
You don’t need the material thickness as a note if you have it dimensioned, if you would like it to be clearer that it’s 1/8th in you can edit the properties of the thickness dimension to have 3 decimal places for the imperial dimension (message in discord about fixing drawing template so you don’t have dual dimensions everywhere, but per the CAD guidelines we use them on dimensions where the imperial dimension is useful, which it is here)