Semi spherical shair glides/feet for angled legs

The plastic chair glides on my dining chairs fell to pieces. The legs are angled but are not cut flat to the floor so I looked at the pivoting glides but I think they're overcomplicated and too expensive once a full set is purchased so I used a hemispherical design instead.

I printed them in 95A TPU (50% infil, 0.2mm layer height), they allow the chair to slide (somewhat) freely when unloaded and grip when loaded. I designed the feet to use countersunk woodscrews with a ~4mm shaft size and 7mm-8mm head but being TPU they should accomodate whatever wood screw are lying around in the parts bin.