How do they work?

[Tony Boadle]

I posted this in Builders' Corner but I'm thinking it might get more views here?.....

I'm renovating an old Fender 400, all is going well so far. I've just worked out the way all the cables operate (really straightforward!)
My question is, how does the lowering set-up work? I've two newly built knee levers ready to fit, they'll be hooked up to the relevant lowering fingers (the ones with the fitted springs), but I just can't work out how they'll operate.
The manual just says attach the cables to the fingers and tune as normal, then adjust the stop screws to the lowered note.
There must be more to it than that? Should the levers have springs attached etc? Help!

[Kelcey ONeil]

It's about that simple. The lowering springs will return the strings to pitch after the lever is disengaged.

[Tony Boadle]

So when my knee moves the lever, the cable will pull the changer finger which will lower the pitch of the string?
That's the bit that was puzzling me, the finger next to each lowering finger will raise the string, so I couldn't work out how a seemingly identical finger (albeit with a spring attached) would do the opposite.
Maybe it's because my main instrument is a b***o. I confuse easily.

[Kelcey ONeil]

That is exactly how it works, The mechanism is very simple and reliable!

[Jon Light]

I simply know nothing about the Fender changer so I don't know if it is a similar design to the all-pull scissor finger.
This gives a good illustration of how a pulling rod (or cable) can raise or lower a string:

https://www.youtube.com/watch?v=xV5ndO4b1qU

[Donny Hinson]

I simply know nothing about the Fender changer so I don't know if it is a similar design to the all-pull scissor finger.

The changer on the old cable-operated Fenders is an all-pull (scissor finger) changer in every respect. The only difference is that the fingers don't pivot on an axle, and this reduces the number of parts required. Most all-pull finger designs have 3 or 4 moving parts (along with a spring) to allow them to operate. The finger design of the Fender accomplishes the same string movement using only 2 parts.

[Ian Worley]

Here are a couple of patent drawings of the original '50s and the later '60s style changer mechanisms. As Donny said, the scissor design works basically the same as most modern all-pull changers in terms of how it transfers the "pull" leverage in two different directions within the changer. The early long scale guitars had the two-part scissor that pulled the string directly from behind over a roller bridge. The later '60s design actually has three parts, the scissor is two, and it actuates the third, the actual steel finger where the string is. I believe from your other recent post that this is the type you have. As you can see in the drawings, they work very much the same as the example in the video Jon posted.

early changer


later changer

[Tony Boadle]

Thanks for all the replies. As the old Chinese proverb says: 'One YouTube video is worth a thousand words'
SGF to the rescue once again!

[Mark Perrodin]

Ian,
those patent drawings you showed are bitchin’. i have only seen the patents that show the whole guitar. i think Fender made a pretty great guitar in the era they came out.they just need lighter return springs to work at their best. cool guitars. i plan on keeping my long scale B6 guitar. and the 17 other 400’s.