How much force?

[Tim2723]

When a typical F-5 stlye is tuned to concert pitch with average gauge strings, how much total force is applied to the instrument? #I'm looking for a general ballpark figure. #Is it 200 pounds? 500 pounds? #A number like that is all I need. Thanks.

[Flowerpot]

I remember a set of J74's being 175 lbs. Somebody correct me if I'm wrong.

[Flowerpot]

OK, more accurately, from the D'Addario site, J74's add up to 181.6 lbs.

<a
href="http:/www.daddariostrings.com/DADProdDetail.aspx?CodaID=725&ID=5&Class=AFPA" target="_blank">J74 string tension
</a>

Hmmm, link no work.

[buddyellis]

Depends on which force and which direction, as the strings break over the bridge at an angle. If you know the string tension, and the break angle you can approximate fairly accurately the downward plate pressure.

[sunburst]

There's also the downward pressure on the top from the break angle of the strings over the bridge. It's around 50 pounds. I tell people to visualize a first grader standing on the bridge to get an idea of what a mandolin is subjected to.

[Chadmills]

Sine of the break angle X 2 X total string tension, or something like that?
Seems to come out close to some experimental figures.
(School was a long time ago.)
Tom

[Jim Hilburn]

But I can only visualize a 1st grader jumping up and down on it.

[Tim2723]

Thanks all. I'll use approx. 200lbs pulling force and approx. 50 pressure. Thanks again.

[amowry]

Tim, if you're interested, I have am Excel spreadsheet on my website that allows you to calculate this accurately based on an existing instrument. With the setup that I usually use, I get 54 lbs on the bridge with J74s, and 57 lbs with J75s (surprisingly little difference, isn't it?).

[buddyellis]

Andrew has a couple of good toys on his website (I especially like the contour maps):

http://home.comcast.net/~nicholsw/mando/downloads.htm

[billhay4]

Thanks, Andrew, for putting these on your site for the rest of us. Very generous.
Bill

[amowry]

No problem at all. I hope they are useful.

[Magnus Geijer]

Andrew,

Those are fantastic! Thank you so much!

/Magnus

[Tim2723]

Thanks again everyone. Those are some neat resources, but I just needed a ballpark figure. I was discussing the topic with a friend who was under the impression that a mandolin must be under hundreds of pounds of force. I didn't know the answer, but thought that the number was much smaller. His experience was with pianos that actually are under tons of force and thus use a heavy iron framework to resist the strain.

Thanks again. It's an interesting subject, and you guys sure know your stuff!!