I have had a 25" 4 heddle Schacht Tapestry loom for 4 years. I have a bunch of other simple frame looms as well , but anytime i need to create a large project I grab this loom. Every single project has had tensioning issues.
Let me stary by saying I always use cotton or linen warping thread. I set the warping tension bar on the lowest tension prior to warping and follow the directions given by schacht for this loom.
When creating a weaving that has 100+ warp threads or even 30+, there is no way with this style to keep the warp under an even tension that I can figure out, In the video online about it they roll the entire warp cone under the looom, leaving no hand tension at all. I still am able to get the loom warped, spacing set, and have my tension at a decent starting place, but as soon as i advance my warp the tensioning goes totally nuts. The middle tends to stay well tnesioned where the side warps on the left and right are slipping all over the place. At this point it doesnt matter how much tension i put on the warp bar... the sides are flapping loose in the winds while the center breaks.
Im really starting to loose my mind with this. I cannot find any info anywhere on thye web about it or anyone else who actually uses this loom. Ive been searching for years PLEASE HELP! i must be doing something wrong.