Regulating Camac Levers

Regulating Camac Leve= rs

Camac Levers are quite easy to regulate, but so= me players seem reluctant to tackle the task because they are not sure which w= ay to twist the bridge pins or shift the levers. This guide was prepared to help pl= ayers understand the mechanics of Camac bridge pin adjustment. The core instructions are highligh= ted in red. The guide also provides some tips = on troubleshooting buzzes and dinks and a North American source for the tools needed to adjust Camac levers.

Most levers are regulated by sliding the lever towards or away from the bridge p= in until it raises the pitch of the string exactly one half step, e.g. C to C#. This usua= lly involves loosening the screws that hold the lever to the neck and nudging t= he lever, tightening the screws then testing the pitch again. It can take three or four tr= ies to get it right.

Camac Levers are unique in that they use a threaded bridge pin. Indeed, fine tuning the lever can usually be accomplished by using a 4, 5 or 6 mm. nut driver to screw the br= idge pin in or out. This is much e= asier than shifting the lever. The = PRECISION afforded by the threaded bridge pins is the most noticeable improvement.

This drawing depicts the side view of a large (bass end) bridge pin and Camac lever. The bridge pin is in a= neutral position - that is the str= ing passes about halfway between the sliding pin and lower bridge fret. When the lever is engaged, it push= es the string down a little more than 1/8 inch (0.15” or 3.8mm).

Bridge pin in a neutr= al position

Now let’s see what happens when we screw the bridge pin in (clockwise), so the string is nearly touching the lower fret:

Low Bridge Pin

Here the sliding pin only has to push the string down about 1/16” (.09R= 21; or 2.2mm) to push it into the lower fret. Even though the lever = is the same distance from the bridge pin, it will not raise the pitch nearly as mu= ch as the first case because it only has to push the string down half as far.<= span style=3D'mso-spacerun:yes'> Now let’s raise the bridge p= in as far as we can, till the string is nearly touching the sliding pin;

High Bridge Pin

Here the sliding pin must force the string down 6.2 mm, nearly ¼ inch into the groove on the lower fret. &= nbsp;

By screwing the bridge pin up or down, one can precisely control the p= itch change of the string as the lever is engaged. If a string is stretchy (long monofilament strings or wound nylon core strings), it requires larger bridge pin adjustments. Short treble strings and steel core strings are more sensitive to bridge pin adjustments= .

To regulate a string, I tune the string s= o it is on pitch with the lever disengaged.&nbs= p; Let’s say the note is C. I flip the lever up and check the pitch again. If the lever and bridge pin are ad= justed correctly, that pitch should be C#, dead on.

If the pitch of the string is too flat (below C#), use the nut driver to twist the bridge pin o= ut (counterclockwise). T= his lifts the string higher. As t= he lever is engaged, the moveable pin will have to push the string down farther into the lower fret. Raising = the string farther away from the neck will make the engaged lever stretch the string more, raising its pitch to correct the flat condition.

If the pitch of the string is too sharp (above C#), use the n= ut driver to screw the bridge pin in (clockwise). Th= is will move the string closer to the neck with the opposite effect. The lever stretches the string les= s on engagement, correcting the sharp condition.

Common Problems and t= heir fixes:

Buzzes:

There are some limits to how far up or down one can adjust the bridge pin. If it is unscrewed it too far, the string will buzz against the sliding pin.&= nbsp; Too low, and the string buzzes against the lower fret. If the bridge pin is near its highest or lowest position, it is a good idea to give the string a good hard pluck to see if it will buzz against the lever. If it does, it will be necessary to shift the lever. <= /span>

To shift a Camac lever, simply loosen the two screws attaching the lever to the neck about a half turn. You c= an use a flat head screw driver, but a T8 Torx is really the ideal tool for the job. Moving the lever towards= the bridge pin will make the pitch of the string flatter when the lever is engaged. Moving the lever awa= y from the bridge pin shortens the vibrating length of the string when the lever is engaged. After you have shift= ed the lever retighten the screws. Y= ou should be able to move the bridge pin towards the neutral position, elimina= ting the buzz. In extreme cases, y= ou may need to drill new holes for the lever. This has to be done rather accurately and may be best left to the builder or a competent repair technician.

Dinks:

A properly placed Camac levers will usually pretty quiet as the lever is enga= ged and disengaged. Sometimes the= lever may be too far to one side or skew, and when the string is engaged, you will hear it go, “dink” as it pops down into the lower fret.

The screws holding the levers to the neck are narrower than the slots machined = into the fret. They have a half millimeter of play (.015 inch). Small misalignments can frequently be corrected by disengaging the l= ever and loosening the screws. The= n push against the lever while each the screws are tightened. The lever does not have to a= lign with the screws. It is more important to align the slot in the lower fret directly under the string. Acute observers will note th= at the smallest Camac Levers don’t have a lower fret. These levers have a groove in the sliding pin. When it is misal= igned it will go “dink” too. The fix is the same.

Two Other Tips

Get the Right Tools

One can screw the bridge pins in and out with an adjustable crescent wrench, bu= t it will really, really help if you get nut drivers. You can order nut drivers and a T8= Torx driver form MSC (www.mscdirect.com):

Item	Part Number	Price
4mm nut Driver	84973734	$6.46
5mm nut Driver	84973759	$6.61
6mm nut Driver	84973775	$6.80
T8 Torx Driver	05059084	$3.65

4mm Nut Driver

Torx T8 Driver

The head on the 4mm nut driver is too large for the tight work around the treble levers. It takes ten minutes = to grind away about 60% of the wall on the tip of the 4mm driver. Do this - the smaller head makes i= t a much more effective tool.

Schemat= ic of the 4mm. driver,

head on before and after grinding

Damp the Strings

A well tuned harp is going to have all kinds of harmonics – other strin= gs that want to vibrate in sympathy with the string/lever being worked on. I get much cleaner meter rea= dings and a better regulation job when I damp most of the other strings. I usually regulate with the harp l= aid out flat, so I can simply place a hand towel over other strings. If one has to work with an upright= harp one can thread strips of cloth between the strings instead.

I would like to thank Larry Fisher of Fisher Harps for his suggestions in creating this tutorial. I inv= ite your comments and questions. =

Please feel free to l= ink to this guide or forward the URL to colleagues and friends that may find it us= eful. Permission is granted to reprint Regulating Camac Levers, as long a= s the copy credits the author and retains the author’s copyright.