Height of springs to use?

[Joys Shop]

I'm redoing a small chair that did not have springs before---only webbing across the top

I want to put springs in it
The frame is 2 1/2" high

Can I use 4" springs?
or
Should I be using 5"

[kodydog]

I'd use 4" unless its a tight seat and you want a high crown.

[Joys Shop]

It is a tight seat, and will be covered in the traditional way

[MinUph]

I'd go with the 5" you're going to tied them down anyway. It will make a better seat.

[Joys Shop]

Thanks
I went with the 5"

What height springs to use has always been a problem for me

[baileyuph]

Joy,

The general rule on tying springs is, compress the spring by approximately 1/3 of its height when tying.  Therefore, using that as a guide in selecting springs, if you go with a 5 in. and tie it down accordingly, the tied height will be about 3 1/3 in. high.  That also means the tied height of the spring will be about or almost 1 in. above the rail of the chair.  

In my opinion/judgement, that will not be too bad, especially if the springs are fairly strong.

In this decision it matters how much the springs would be comprssed when sat on.  Of course, it depends on the person and how big, that sort of stuff.  

I wouldn't go less than a 5 in. spring, possibly a 6 in. and tie it to about (between 3 1/2 and 4 inches) to prevent the user of pushing them down close to or less than rail height.

Crown is important also, if the chair would look better with the crown, go with a 6 in, tie it to 3 1/2 inch.  Especially, if you go with a small fox edging.  The six inch would need to be a softer guage, however.

One can expect some sag in the webbing and all so the 2 1/2 in side rails with a tied height of about 3.5 would be a doable ratio.

More succinctly, there is one parameter not given and that is, the tied height and more should factor in the spring guage.  Very important because one should consider the strength of the spring.  

Stronger spring would probably discourage selecting a 6 inch spring, and so on.

Good question!


Doyle

[mike802]

I have found spring selection to be more of an art than a science.  A taller spring will usually give a softer seat, but to high can lead to an exaggerated crown. Don't expect to get the springs tied down to seating height on the first front to back tying, you will also have to pull them down some on the side to side tie also. But I like to tie my springs tight, relying on the springs to regulate seating softness, or firmness, not the tying itself.  The webbing will stretch and sage some, this is normal and I would say essential, if no sage the springs are not tied tight enough, in my opinion.  I also use spring up nails, not webbing tacks, a properly tied spring system will pull the webbing tacks out.  Always make sure to drill a pilot hole for the spring up nails to avoid splitting the frame.  You might also notice the frame rails bending in some towards the springs, again normal, it's amazing just how much tension the springs apply to the chair when properly tied down.  I mention all this because I see so many springs tied wrong, about 80% of the furniture I reupholster has improperly tied springs.  One upholster just follows what he, or she found and the mistake just keeps getting repeated.  I like to stuff some cotton into the inside of each spring, pulling it out so the springs wire can't rub against each other, gives me a little insurance against a noisy spring.