The Mudcat Café TM
Thread #156010   Message #3675398
Posted By: Richard Bridge
07-Nov-14 - 07:30 AM
Thread Name: machine heads - any opinions?
Subject: RE: machine heads - any opinions?
Waverley, Kluson, Gotoh, Schaller, Grover - all good.

I second what is said above about machine heads "slipping". It is mathematically demonstrable that a worm with a ration of 14:1 or higher will NOT "overhaul" as it is called in theoretical mechanics.

However, it is also the case that if you have three turns around a post, that cannot and will not slip either.

The most likely cause of tuning instability is (IMHO) friction at the nut, particularly if you are a string bender - you pull the string sharp, that stretches the bit behind the nut - you let go and one of two things happens - wither it stays stretched due to the friction so the string is now flat, or it pings back a bit too far so the string is now sharp. The latter should not happen if you ALWAYS ALWAYS tune upwards. If you go sharp, flatten the string and tune upwards again. This also eliminates or, to be technical takes up any backlash in the gearing.   

You get less friction at the nut with coated strings, and you can if you like lubricate the nut with powdered graphite.