Hi there, Sorry, I only just read your post today. It's a year and a half old.
I made Soba for Oshogatsu in Japan with my friend's father and brother. They make it every year for the holiday. I was invited to spend it with them that year. They recommend, and we made it this way, a 75% to 25% buckwheat to wheat flour recipe. Otherwise, the soba pasta is too hard and breaks too easily. That is how their family has been making it.
I have video footage of it but haven't edited it into a reasonable length video. Someday I'll get to it and post on my site Daily Prandium (.com).
I just made my first "impromptu" towari (100%) soba the other day, the details and pics of which you can find on my Flickr post ( http://flickr.com/photos/akatayama/se... ).
The trick is to fresh mill the sobako yourself. In my case I used a large and manually operated Chinese stone grain mill. And the other trick, at least when using the rustic stone mills, is to turn it slowly, around 4 seconds a revolution, and at the same time to feed the grain very slowly.
But note that this is just my first attempt, so I've got a long, long way to go. Hope this helps!
Although "The Book of Soba" seems to be "The" English reference, I've found that the technique books written in Japanese to be much more to the point and careful with their instruction. I've found that when comparing teuchi soba books that "The Book of Soba" offers a much simplified and abbreviated method when compared against the Japanese technique books.
Funny you should mention it... I just tried making it a few weeks ago. It did not go well, and I have pictures to prove it (a friend told me they looked like anchovies). See my blog below. I got the recipe off the Internet from a soba-making school in Japan. But the next round I will be making from a cookbook I just got called The Book of Soba.
Generally, they say it's incredibly difficult to make with 100% buckwheat, the highest percentage they recommend is 80/20, with the 20 being wheat flour.