string load in lbs

[Martian]

I am starting a new F-5, W/ Hogos plan, and have forgotten a lot of stuff.
The Lefty Luthier' used to help me quite a bit, but I believe he retired, and he helped me with " deflection tuning" I need to know how much weight is on a bridge when fully loaded with a set of strings, and in tune. i thought it was 38 lbs, Hope I am not getting in over my head,lol

[OneChordTrick]

Someone more knowledgeable will doubtless be along in a minute but I think its total Tension multiplied by the sine of the break angle. From memory the total tension in a set of EJ72s is about 180lbs. So with those strings and your 38lbs would imply a break angle of around 12^o. Which, if my maths is right, is in the right ball park.

[Martian]

what I had done, was built a jib, and loaded up the bridge are by putting a digital scale on under the loading point,( bridge area), and adjusted the weight on the handle end to increase the weight to what I needed , I cannot recall what I needed, Siminoff says 38 lbs in his ' art of tap tuning book"

[amowry]

You can use the calculator I have on my site: https://www.mowrystrings.com/neck%20...alculator.html

It’s about 55 lbs downward force on an F5 bridge with J74s. However, you don’t have to use the full force for deflection tuning, as long as you’re consistent from one instrument to the next (I use about 25 lbs). I don’t think deflection tuning is very useful for one instrument because it’s hard to know if your setup is comparable to someone else’s, but it’s useful for comparing multiple instruments that you’re building.

[sblock]

This topic came up in a recent thread, so you might want to look for that. The full (linear) string tension is somewhere from 150 to 200 lbs, depending on the gauges, for all 8 strings. Depending on the string break angle over the bridge (say, 12 degrees to 18 degrees), about 20% to 30% of that full tension appears as a downbearing force on the bridge saddle, acting down on the top. So, roughly 30 to 60 lbs of force.

[Martian]

thanks to you all!!