Designing a stair stringer in Carbide Create

WillAdams · January 1, 2026, 3:41pm

as requested on support…

(from the “If all you have is a hammer, everything looks like a nail department.”)

Making stair stringers is a frequent task for a carpenter. Described at:

it’s pretty straight-forward, but it might be that there is something interesting in the process for folks using Carbide Create…

First, a few dimensions:

total rise — how much the steps will go up
number of steps — divide the rise by a reasonable dimension for the desired riser height (usually 7 to 7.5") round up (or down) as desired
actual riser height — determined by dividing total rise by number of steps
tread depth — usually 10 or 11 inches
tread thickness — determined by the product being used, e.g.,

https://www.homedepot.com/p/EVERMARK-Stair-Parts-48-in-x-11-1-2-in-x-1-in-Unfinished-Pine-Plain-Cut-Engineered-Stair-Tread-8530E-048-HD00L/202087175

There are a few other dimensions which may come into play:

finish floor thickness at the bottom of the run
finish floor thickness at the top of the run

(if those two values are different)

as well as a final consideration of where/how the stairs will be secured at the top, which will probably require:

sub floor thickness at the top of the run

Lastly, there is the matter of tread overhang and any additional hardware such as stair corners.

Given all these, it should be pretty straight-forward to just draw up the profile of the stairs and the matching structure, use the Measure tool to get some dimensions, then use Linear Array to duplicate Stair Treads (or a proxy for same), then finally, use the measure tool to get the angle of rotation for a 2x12 and Boolean subtract the stair treads (and the space above) so as to arrive at a stair stringer which may then be measured and cut traditionally, or if one wishes to go the full monte, cut on the machine using tiling if need be (but of course that would then require a bit of adjustment in the stair treads (rounding over the bottom edge to match the radius of the tool used) as well as sourcing a “long reach” tool to cut through 2" construction lumber.

WillAdams · January 1, 2026, 5:52pm

First, draw up the profile of the area where the stairwell will be installed — I will use the dimensions of the stairs down to my basement (note that this is an old house, originally built w/ an unfinished basement, and I’m pretty sure the stairs in question were replaced as part of a modification to add a linen closet):

finish floor thickness at bottom of run: ~9mm (vapour barrier, pad, and carpet)
finish floor thickness at top of run: ~19mm (white oak)
sub floor thickness at top of run: 1/2" plywood, so 12.7mm
total rise: ~2110mm
total run: ~2400mm
tread thickness: 25.4mm (from the above Home Depot link)

We will determine the riser height and tread depth (which I would not recommend emulating) from the above.

Start by setting Job Setup:

Draw in a rectangle:

and position it:

and then subtract the sub/finished floor dimension from top and bottom:

and adjust the position:

We then re-draw the original:

and subtract only the bottom finished floor dimension:

and re-position it at the top:

and duplicate it and divide its width dimensions by the number of steps:

and the height by the number of steps plus one:

Done

This may then be positioned at the height of the lower floor:

and duplicated in a diagonal:

(and an extra rectangle removed if need be)

Next, draw in the stair treads w/ overhang:

and round to show the bull-nose:

OK

Drag into alignment at the first stair step:

Then select all the rectangles which represent steps:

and drag down by the height of the tread:

Draw in a replacement at the top:

It should now be possible to measure the 2x12 needed:

Draw it up:

then rotate it:

Done

and drag into position:

Then measure the diagonal at the top right:

and subtract the top finished and sub floor:

and then draw in a rectangle:

which allows one to determine how much up and over to move the 2x12:

Then measure how much the overcut is:

and move the 2x12 that much horizontally:

Done

Then simulate the various cuts:

This will be simplest if the diagonals are all connected:

OK

Select the 2x12:

shift-click on the unioned object:

and Boolean Subtract:

Make the last cut:

OK

Rotate back to level (or vertical) if need be.