Enlarged Sett

[Calgacus]

Kyle, scaling from your friend Duncan's photo it would appear that his sett is about 12".
With that in mind, and the fact that the Dalgleish 18oz fabric does not appear to use thicker threads, I'd say your only option is to go with the regular Chattan (clan) sett which will be a shade under 10", or attempt some tweaking of the sett to enlarge it to 12" or more. I think you would be best to do that by carefully increasing the thread counts of the wider stripes only and trying to maintain the balance and overall appearance of the tartan. Technically, you'd be creating your own sett or at least variation of the Chattan sett, so you may wish to run that past your friends/family/chief so as not to tread on any toes.

I too am interested to see what comes of all this, as it has a lot of bearing on my own ideas for a custom weave. Having bought swatches, I discovered that neither of the mills that produced Johnston Weathered actually stuck properly to the Johnston sett! The thread counts of the actual samples varied from the registered sett, and from the computer images shown on their websites. Not a big issue, but it was the thin stripes which were wrong, and it was fairly noticeable (to me, at least). Anyway it was enough for me to think 'stuff it, why not design my own tartan, given that my patrilinear family has no tartan and is just a sept of a border family'.

Don't hold your breath though, this is a long term project, there is a long list of things higher up the priority list for my disposable income.