What does a Stair Saw do?

[Brian Kent]

Sometime in the next year I need to replace a flight of stairs (too steep, too narrow a tread, no nose badly finished with Pergo trim. I have to walk down sideways for my feet to fit.)

I am curious how one would use a stair saw. I have never seen one in person. I think they create a dado, but I don't know what part of the tread that would go on. Is it a dado to fit over a stringer, with a tread overhanging on the sides????

Thanks in advance,

Brian

[Chris Vandiver]

Brian,
A stair saw is used to create a dado in a housed stringer, among other things. This dado accepts the tread and the riser.

[george wilson]

You can only use it while standing on the stairs.:) O.K.,it also is stopped off by the wooden handle/saw back,so it cuts to a certain depth.

[Joseph Klosek]

If you are talking about making the treads wider, then you will need to remove the entire set of stairs and start over. Since you will be changing the run of the entire staircase.

Just adding wider treads will most likely make them overhang the risers by too much and therefore end up adding to the hazard of using the stair.

What is the rise and run? How far do the treads project over the risers?

You will likely need more than just a stair saw to get this done.

Is this a main staircase or secondary one?

J.P.

[Brian Kent]

Chris, is that the definition of a housed stringer, one that has dados that accept the tread and riser?

George, that sounds like it could come in handy for other dados too.

[Brian Kent]

Joseph, I do not want overhanging treads. I was just asking if that is what the stair saw is used for.

This is my primary staircase that I need to rebuild.

The current rise is 65.5".
The current run is 72".
There are now 9 risers and 8 treads, with no nose on the treads.

I will be adding one or two steps and increasing the run as much as architecture will allow, probably to 106". I'll add a 1" to 1.5" nose on each tread.

I am not planning on using a stair saw, but just wondered what they were used for when stairs were made by hand.

[Brian Kent]

…and i'm just gaining knowledge for now, not making the actual plans.

I just wanted to know what a stair saw is used for. :)

[Andrae Covington]

Chris, is that the definition of a housed stringer, one that has dados that accept the tread and riser?

George, that sounds like it could come in handy for other dados too.

See housed stringer diagram below. If not an open stair then there would be dados for the risers as well.

http://oak.arch.utas.edu.au/tech/images/construction_details/2.0x/251.gif

source (http://oak.arch.utas.edu.au/tech/construction_details/2_07_1.htm)

[Andrew Gibson]

and here all this time I thought they were called stare saws.
The kind like George and others make around here that you could stare at all day.

[greg Forster]

Brian:

with a 65.5" raise, your current 9 risers/8treads is perfect- it gives you a rise of slightly over 7 1/4", the problem is the treads, aim for 10 3/4" run with a 3/4" nosing for 11 1/2" tread width. your total run would be 8 x 10.75"= 86" + the 3/4" of the bottom tread nosing. 1" of nosing is the most you'd want anymore and it will be a trip hazard. I wouldn't add steps
( decrease your rise per tread), with a 7.28" rise and 11.5" run per, you will have a set of stairs with a very nice gait as you ascend/descend them.
Too shallow a rise is as bad as too narrow a tread.
















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[Brian Kent]

Greg, that would sure make it a lot easier to fit in the space.

[Chris Vandiver]

Brian,

One of the "rules of thumb" for stair building is that the the sum of the rise and run for one step should equal between 17"-18". There may be other things to consider but on the face of it, you need to increase your tread depth to a minimum of 9 3/4".
Given the overall rise of your stairway at 65 1/2" with 9 risers, each step should be 7.27".
It may be that you can simply add on 3/4"-1" of nosing but it does depend on how the stairs were constructed in the first place. It is easy to compound errors on stairways. Small errors are often multiplied over the number of treads or risers!

[harry strasil]

In all the old tech manuals I have, the formula is 2 times the rise plus the run = 24.

Some inspectors want each rise to be 7 inches no matter what. I was redoing the rear stair entrance to a local bank and the inspector came around and being that the rise was not exactly 7 inches, he wouldn't sign off. So I just tacked the treads in on the other side of the landing at 7 inche and then told him to close his eyes and walk up them, turn around and walk down, I large step at the top almost got him, I caught him before he went down them head first. He signed off and told me to make them like the first side. LOL

[Gaz Palmer]

Aside from rise and going, head clearance also needs to be taken into consideration if your staircase falls within a stairwell. The minimum UK standard is 6'6" head clearance between nosing height and ceiling and becomes especially important if the floor above overhangs the stair.

[Joseph Klosek]

Are you planning on using hand tools to build the stairs?

Is this a closed stair with walls on both sides? Or open on one or both sides?

J.P.

[Bill Rhodus]

Brian, I bought an old stair saw from ebay and found it to be a handy tool for a variety of tasks. However, a traditional stairsaw has the blade centered in the wood thereby making it difficult for a minimally talented woodworker such as myself to work with. In order to use a batten I had to offset it the thickness of the wood so that the saw would cut on the line but the saw also obstructed the line. I built the attached saw to overcome my shortcomings. The saw blade was taken from an inexpensive Stanley crosscut saw and the wood is a scrap from my shop. The "push-pull" arrangement was inspired by an old plane I had seen (Stanley door moulding plane?) at some point and this allows me to turn the saw end for end to always be able to see the saw on the cut line. I also made the depth stop adjustable so that I can vary the depth.

[Brian Kent]

Joseph,

I am planning on using power tools for the stairs.

They are closed on both sides.

I started the thread not knowing what a stair saw was, to see if there was some part of the process that would be better, or more fun, with neander tools.

Nice tool, Bill!

[Joseph Klosek]

If you are planning on making a closed stair in your shop and then assembling it in the house, then you could use the stair saw for fun just to get the hang of it.

All of the closed stairs I built were just nailed together on site over the rough framing. I did use a version of pocket screws to join the risers to the skirt so the treads wouldn't push the skirt apart and leave gaps at the riser.

The trickiest part of doing a housed stringer/skirt board is getting the right distance from the nosing of the tread to the edge of the skirt.

Since the run of your stair is fairly short you could use the stair saw to cut the trenches for the treads and risers fairly quickly, Maybe 1 or 2 days depending on how hard you work at it.

The housed stringer/skirt board is the best way to make a solid and gap free stair.

J.P.

[Paul Incognito]

Lots of (good) advice on how to build your stairs here, but no answer to your question. I may be wrong, so if someone here knows better, feel free to correct me...
A stair saw cuts the initial grooves in the stringers for housed treads and risers. A hole is drilled at the stair nose and the top and bottom of the groove get saw kerfs with the stair saw. Then the area between the kerfs gets hogged out with a chisel or router plane, creating the dado for the treads and/or risers.
Clear as mud?
PI

[Brian Kent]

My imagination tells me I understand.