✅ Designing a replacement knob: how do I measure a D-shaft accurately?
@spokes_n_sprockets
Oct 10, 2026 · 1.1k views
Washer knob snapped. Shaft is a D profile. Calipers give me 6.0 across the round and 4.6 across the flat but my print is loose.
22
1 replies
✅ Accepted solution
Print a tolerance test first: five knobs at 6.0/4.6, 5.9/4.5, 5.8/4.4 and so on. Holes print undersized by 0.1 to 0.3 depending on the printer, so your "loose" may actually be an oversized model. Also add a small set-screw boss with a heat-set insert; then the fit does not have to be perfect.
29
Log in to reply.