The Nut Is the Shoulder

The clutch was binding

After the first full run, the clutch started binding. Tighten it enough to drive and the motor stalled. Back it off and the nut walked loose.

The problem was how I had stacked it. The clutch was clamping against the motor itself, so every bit of squeeze I put on the stack went straight into the little gearbox, which is not built to take it. The stack needed something of its own on the shaft to push against: a shoulder.

A shoulder is a manufacturing problem

The motor shaft is custom anyway, so I asked my motor supplier to machine a flange onto it. They said no, and they were right. A flange big enough to matter hit their case screws and my mounting holes, and turning a step into a shaft that small is expensive. A flange small enough to clear would not have done anything.

The nut is the shoulder

So no flange. The shaft stays the same diameter all the way down, and the thread just stops a couple of millimetres short of the gearbox. A nut runs down and bottoms out where the thread ends. That nut is the shoulder. The clutch clamps between it and a second nut, the whole stack holds itself together on the shaft, and the gearbox never feels it.

Left to right: the new motor with the full clutch stack on it (the gear sits between the two fiber washers and is left off here); the new motor bare, with the plain band at the bottom where the first nut bottoms out; and the original motor, with a short thread and nowhere for the clutch to land.

No new part, no machining, nothing for the supplier to get wrong. The drawing changed by two dimensions, and that solved it.

Why it cost two months

Two dimensions on a drawing still means new motors. The ones I had could never hold the clutch: the thread was too short and there was nothing for a nut to bottom out on. So the fix was a new shaft, a new sample run to prove it, and then a production order on a 45-day lead time. That lead time is the whole reason the first units moved from September to November. Every motor in that order has the shaft that works.

The TiltRod, by TiltForge, is a retrofit smart blind motor — repairable, open, Matter-native, and the cord always works. Founders pricing on the first 100 units; first units ship November 2026. Check your headrail at tiltforge.com/fit or follow the build at tiltforge.com/#waitlist.