Hi,
I need to make a 130:1 reduction worm drive and I intend cutting the gear on a lathe with a tap. This is the first time I've attempted anything like this so I was hoping someone could look over my plan and tell me if they see any issues.
The worm will be a section of 16 mm (2 mm pitch) all thread and the gear will be cut from Delrin. Being 130:1 with 2 mm pitch the circumference of the gear will need to be 260 mm (82.76 mm diameter).
The gear will be mounted neatly on a vertical shaft on the cross slide in a lathe such that it can freely rotate but have no up/down movement. With the tap in the chuck, feed the gear into the tap until it makes light contact then rotate the chuck by hand while gently feeding the gear further in so that it begins rotating from the cutting forces.
Start the lathe and continue feeding the gear in until tap has fully engages (cut depth equal to the height if the thread) around the whole gear.
Sound OK?