Creating a warp for a warp-weighted loom can actually be done using several different methods. This is my preferred method, and is a mixture of tablet weaving and measuring out a warp at the same time.
1. Pick a location where a tablet weaving band can be securely attached, with enough space on one side to accommodate the required length of warp, wrapping around a post or other object (to split the warp into two or more sections, based on the type of weave being used: plain weave. twill, etc.).
2. Warp up 6-8 tablets, alternating S and Z threading, with enough thread to weave a band the width of the desired warp plus enough to allow space for the tablet and twist build up. Stretch them across the chosen location. This will be the header band for your weaving.
3. Start the header band with waste thread as weft, to establish the weave. You will be weaving with the tablets always turning the same direction (usually, away from the woven area). (You can use any type of tablet weaving pattern you want to create this header section — plain weave with the tablets always twisting in one direction is the simplest pattern, and is suggested as best for weavers who are not experienced tablet weavers.)
4. Take the thread intended for the warp of the main project, and insert a loop as weft through the header band, so that the thread hangs out as a tail from the side that will accommodate the warp. (The loop will ultimately be split so that the halves become the front and back warp threads.)
5. Take the loop of thread down and loop around the far post.
6. Turn the tablets a quarter turn, and beat the thread in tightly.
7. Bring the loop of thread through, once more, beat and turn, and take weft/warp down and loop around post, again.
8. Continue weaving in this manner, leaving long loops of weft to be used as warp. When the header band is long enough (the warp is the needed width), end the band with a thread long enough to secure the end in the main weaving.
9. Tie the warp into bundles of approximately 8 threads each, keeping front warp threads separate from back warp threads. Use enough ties to keep threads under control. (There is no such thing as too many ties. You’ll appreciate this later as you weave.)
10. Secure header band to warp rod with thread. Attach warp rod to cloth bar, lacing rope through holes. (This helps secure your warp rod, lessening the chance for it to sag from the weights being added to the warp.)
11. Assemble the loom. Hang the cloth bar in place. Chain up the warp so that it will not hang on the ground.
12. Attach weights to warp bundles, so that weights clear the ground.
13. Knit heddles onto heddle bar, in the pattern needed for selected weave. (This sounds quick and simple here — trust me, it’s not. Allow plenty of time for this procedure, and rest assured that you will never forget how to tie the needed knots, once you finish.)
14. Chain together weights, to keep them in correct positions.
Please let me know if you have any questions!