mk2 leg knee stud

One of the parts on the original quad A0’s leg that was prone to failure was the “knee stud”, a little cylinder that acted as the mating interface between the upper leg and the lower leg.  It directly attaches to the upper leg, and has bearings that ride between it and the lower leg.  The entire tension of the leg belt is born in shear by this part.

20200206-knee-stud

In the mk1 leg, this part was 3d printed with heat set inserts used to form the threaded holes.  This mostly worked, although occasionally the stud could shear along the 3d printed lamination lines.  Thus, for the mk2 leg, I’m making this part out of 6061.

dsc_0204-1

The first op takes a 0.875 inch cylinder, and does all the work on one of the sides.  That includes roughing it down to length, getting the outer diameter that the bearing rests on accurate, and drilling and threading the holes.

dsc_0222
5x knee studs with the first op done

At that point, the part is turned over and bolted into a 3d printed fixture.

dsc_0223

Then, all the tool paths are repeated on the other side, as well as the middle being cut away.  I didn’t really worry about surface finish on the middle section, since it will never be seen.  This of course would be much easier on a CNC lathe with live tooling, but hey, you use what you’ve got!

dsc_0228
All 5 that I made

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s