This should be simple.
How do I tie knots in a rope in a very precise spot on the rope.
I am tying small brown twine into a rope ladder with solid cross pieces. But I am not familiar with a method to insure that my knots end up right where they should be to make the two side pieces come out even.
Hi Bercky
If the solid cross pieces are cylindrical, you can use a marlinspike hitch, which is the same as the slip knot.
The only difference is that the slip not is used in such a way that it does not capsize into a noose.
Have a look at the article in wikipedia.
http://en.wikipedia.org/wiki/Marlinespike_hitch(btw. in the German version it is specifically mentioned that it is used for rope ladders, along with its weaknesses when doing so)
Finding the right spot for the knot is always a bit of trial and error, but because of the simplicity of tying the slip knot/marlinspike hitch, it is easy to undo and re-tie a bit further up or down as needed.
It is not designed to work with square rungs or flat boards and another draw back is that
the rungs only stay in place, as long as there is a load on the ladder (gravity might suffice, when the ladder is kept hanging down)
and the rungs could also slip out the sides.
To adress these problems, you could fix the rungs into place with lashing techniques.
You can find some in this document:
http://www.bsatroop996.com/Lashings.pdf
Alternatively, since the "ladder" is not going to be supporting much weight, I could tie the cross members directly to the vertical pieces. I may actually prefer this as my knots would probably be smaller.
The above Lashing document should give you the right idea.
P.S.
if the twine your are using is long enough, perhaps this might be an alternative (it does not need any solid cross pieces at all):
http://notableknotindex.webs.com/ladder.html