this is a add on extension to be able to have a little more adjustment and a bigger size splitter pole for a little more durability and accuracy

stair tread jig credit goes to BCFirefighter https://www.thingiverse.com/thing:2883960
his summary is:
Jig for transferring the exact length and end angles to a new stair cap.

Print Settings
Printer:
Anet A8

Rafts:
No

Supports:
No

Resolution:
0.2mm

Infill:
25%

Post-Printing
Materials Required
2 - 1/4" x 1 1/2" Hex head bolts
2 - 1/4" x 1 1/2" Flat head bolts (countersunk)
4 - 1/4" Wing nuts
4 - 1/4" Flat washers
1 - piece of lumber cut to fit jig (~10mm x 20mm)
I cut this on my table saw, shaving slightly until a perfect fit
Length is determined by the width of staircase - I cut mine so the jig was centered on
the adjustment when in place on stair tread.
The holes in the lumber for the countersunk bolts are drilled slightly undersized so
the bolt "threads" into the board.

How I Designed This
Ever tried to layout 'enclosed' staircase treads????
Decided to build my own stair tread caps. First measure and fit went pretty good, but not as good as I wanted. Thought there must be a tool for this job and searched online. After looking a few designs over I choose to design and print my own rather than drop $100 to $150 on a commercially available one.

Creality

Ender 3

No

No

.2mm

20