Monday, February 8, 2021

Linear Actuator, vol1

One of my larger flight vehicle projects requires... 3 linear actuators. They need to have high support force, fast stroke speed, closed loop, electric, and be easily programmable. This is a tall order for most any linear actuators on the market. I did get some quotes from people, and it turns out the're like $5k a pop. I definitely cannot afford that, so I have to make them myself. Which is also fun :)

I got inspiration from two sources: 

Gabrael's linear actuator uses a BLDC motor with a traditional ball screw, but also two 16mm carbon fiber smooth rods: one acting as a guide and the other as the end-effector. WeWato does something similar, but with more carbon guiding rods. Each seem to use drylin smooth glide bearings, which are cool..

I have started my design here... There are still some more blocks to make, but figured I would post this update. The end-effector is steel, and requires weldnuts for the heim ball joint at the end. I could have tapped the tubing, but then I would need a large heim or some weird adapter. The weld nut seems easier.. just need a small weld bead. (I don't have welder... yet...). 

The next step is to make the retainer block: the part after the coupler, which prevents the ball screw from falling out, and attaches the assembly to the motor. Then I will add in some guide rods (maybe using the existing holes in the ball nut??) and an end guide holder. Then I think a sheath of tubing over the whole thing.. and some way to mount the back of the motor. All in flux, but I am learning a lot and having fun..

The "Import Mcmaster Carr Part" feature of Fusion360 is unbelievably fuckin powerful, and is totally dangerous :)

cutaway shots are sweet....

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