https://ibb.co/r2xJ0Bg8

Note- Title was being edited when it uploaded and now I can't change it ....it should read ' Can block weave structure cause uneven warp tension?' ).

I am weaving my first block weave structure using my Jane loom (see draft included) using 8/2 cotton with a sett of 18 epi (which I now know is really too low...probably should have gone for 20 epi or more). Anyway, I am having a couple of issues. When throwing a pick , the already woven fabric forms a series of 'hills and hollows' making firm beating problematic. This issue can be partly solved if I lower all frames before beating on what is then a flatter warp. However this is quite time consuming, as normally I would change shafts between picks by lowering and raising levers/ shafts at the same time. It may be that this problem is partly due to not advancing the warp frequently enough now that I think of it.

The other more significant issue is a loss of tension in some threads on the lower shed. I will include a photo of this in a follow up post, because if I try to do it now, this whole post is likely to vanish. I wonder if it has something to do with uneven take up of warp threads in the 'framer' sections of the weave, compared to the squares??

Any insights or suggestions welcome, as I am now hesitant to try this weaving structure on a larger scale on my David in case it all turns into a bit of a mess! Thanks. ( Note- photo of loose warp threads to follow...hopefully!)

https://ibb.co/8LmhRrv9
https://ibb.co/V0FZxzDq
https://ibb.co/23kxfBf9

When shafts 4,6,7,8 are raised (levers down), the threads forming the bottom shed from shafts 1,2 and 3 are noticeably loose. When no shafts are raised, tension across all threads returns to normal and is even across the warp.

Thanks very much for your reply Sandra. Yes the tension seems to be pretty even across the warp when all shafts are lowered ( see photo in follow up post). The threads that seem to go loose are threaded through the front shafts which actually carry very few threads e.g. shaft 1 only carries two threads for every 6 threads carried by each of shafts 5, 6, 7 and 8.

I know 'take up' usually seems to refer to the width of the weaving, but can there be variable 'take up' among warp threads along the length of the warp as well? e.g. if a particular warp thread is going under and over weft threads far less often than an adjacent warp thread, would the first thread not lose tension over time, compared to the second one? I really don't know if that question makes any sense at all, but it's just sort of a vague notion floating around in my head!! Although I think I may have heard Jane referring to this somewhere....I have a bad habit of sort of rambling around through the various seasons while actually focusing ( at least in theory) on one! A bit like browsing through the menu in a restaurant to see what you might go for the next time, while still enjoying the meal in front of you if you know what I mean!

The reed is an 8 dent reed as it seemed to get me closer to 18epi using 2,2,2,3 sleying sequence than the best I could get on the 10 dent reed. Of course, as I mentioned earlier, I now think I should have gone for 20 epi or higher, would you agree? Thanks again for your help!

https://ibb.co/cnHN8bg

Here's the photo showing warp when all frames are lowered.