Today, we did the following!
We modified the base by shifting the position of the two long aluminium profiles within the base so that they can support two adjacent vertical aluminium profiles that would serve as the vertical support tower.
The below photo shows us “in the flow” as we adjust the two aluminium profiles within the base. The modular design of the aluminium profile assembly makes it relatively easy to make any adjustments we wish: we simply have to unscrew the brackets, shift the position of the aluminium profiles, and then rescrew the brackets. However, for longer and larger profiles like these, the brackets are larger, and also harder to be adjusted and screwed precisely, so this took some time.
Once the base was ready, we proceeded to cut the aluminium profiles for the support tower (2x 1.5m), and then attached the primary lifting arm with its actuator.
The below video shows us cutting the profile with the aluminium cutter.
This photo shows the heavy-duty brackets we used to secure the vertical profile with the horizontal profile on the base. We made sure to get high-qualtiy heavy-duty brackets from Prestech (even though they are significantly more expensive) as this joint bears the entire weight of the whole arm and it is extremely important for the integrity of the arm.
After attaching the two vertical aluminium profiles, we had to attach the pillow blocks to serve as the freely rotatable joint between the primary lifting arm and the two vertical support profiles. This video shows the process.
The first linear actuator (attached to the vertical support tower using the actuator brackets that we bought) will then provide the control needed for the primary lifting arm. The below photo is the completed assembly of this stage, and the video below that shows the actuator in action – as the actuator extends, the primary lifting arm is raised higher, with the pillow block as the pivot.
Neat! The actuator is able to smoothly control the angle of the primary lifting arm without any problems, for now. As per our calculations and hopefully, it should retain this smoothness when the secondary lifting arm + clamping system + 18kg load is attached.
We decided we had enough of the main arm, and we continued working on the clamping mechanism. Today, we designed and 3D-printed customised clamp grips (2 completed 3D-printed grips, 1 currently printing) and then tested them out. Where needed, we also paired these grips with appropriate clamps.
1) This yellow clamp below will lock onto the rectangular reliefed part of the pneumatic unit using the two screws on the relief (highlighted below with a red box). This will be done by simply pushing in the yellow clamp into the reliefed part, which will then help to prevent any unwanted vertical motion of the pneumatic unit.
2) We had also 3d-printed another red grip (on 1st July) to lock onto the thick brown metal wires. However, we had yet to attach a clamp to the grip, so we did that today. We also optimised the relative distance of the clamp and the aluminium profile attached to the red grip to achieve tight and smooth clamping of the brown metal tubing.
This video shows the initial clamp, which was not tight and also suffered from a rough, disjointed motion. Thus, we adjusted the aluminium profile (on the left) attached to the clamp closer to the right, nearer to the profile (on the right) attached to the red grip. The second video shows a much smoother motion of clamping. Hoorah! #Optimisation
3) We also 3d-printed a black grip that would fit into the relief with 4 big screws on the unit. When done correctly, this will be a very good, tight grip that would prevent motion in all directions except the horizontal, forward direction.
To refresh your memory, this is how the clamp should go in.
<to show photo/video of the black grip going in with the assembly>
4) Another good point to grip is shown below: Again, we chose to clamp from the side, rather than from the top. We set about designing the clamp, and it is currently printing! We shall test this grip with a clamp when it is ready.
5) Yet another good place for a grip is this: a pair of very solid-looking bolts that could be gripped from the vertical direction. We have to be careful though, as we well know by now, the vertical clearance is limited, so the height of this clamp system has to be as short as practically possible.
Below is the solidworks file of the clamp. The two holes at the end will fit into the two nuts, and the hole in the middle is for the M6 screw to secure this grip into an aluminium profile.
However, when we printed and tested this grip, the holes were not aligned (unfortunate!), which meant more precise measurements and careful adjustment of their positions in the file. Also, the protruding ledge was too long, and the grip could not fit into place. We shall redesign and reprint, and then test the revised grip tomorrow.