So many projects in Handwoven are now for rigid-heddle looms. I am wondering if there is a way to convert a rigid-heddle draft to a 4-shaft or 8-shaft loom? I'm especially interested in weaving the Stash Vest (by Deborah Jarchow, September/October 2012, page 41).
You are in luck—this is pretty easy to do! The question we usually get, which is not as easy to answer and sometimes not even possible to do, is the opposite: How do you convert a 4-shaft or 8-shaft draft to a rigid-heddle loom!
If the rigid-heddle project is plain weave (as the majority of them are), all you have to do is thread your 4-shaft loom for plain weave, being sure to observe the same sett (in this case, since the project uses an 8-dent rigid heddle, you'd need to sley 1/dent in an 8-dent reed. One advantage the rigid-heddle loom has over a shaft loom is the capacity for weaving with relatively loose tension on the warp, making it possible to use some stretchy or fragile knitting novelty yarns that are a little harder to manage on a shaft loom. There is also less loom waste with a rigid-heddle loom, which is an advantage if you are using expensive novelty yarns. The yarns in the Stash Vest are mostly rayon so not likely to be stretchy. Project directions for the vest allow sufficient loom waste for a shaft loom. I'd use your 4-shaft loom and thread 1-2-3-4 and weave plain weave by raising shafts 1-3 vs 2-4, alternately.
When rigid-heddle projects involve pick-up patterning (as for some lace weaves, for example), it is harder to adapt the project instructions to a shaft loom. The slots made it possible to do pick-up behind the rigid heddle and leave the pick-up stick in place as you weave several picks. When you do pick-up on a shaft loom, you usually have to make the pick-up for every weft row. Rigid-heddle projects that use two rigid heddles can be woven on a shaft loom, but you usually have to understand the weave structure being produced to translate 2-heddle drafts into a draft for shafts.