I'm hitting on this topic again for anyone that might be interested in trying the buttonholer on a treadle.
I have made several buttonholes now and all of them are topnotch (in my book anyway). The only issue I have, and I feel it's operator error, is I don't have the clearance under the foot like I think I should have. After I get the next two projects done, I plan on disassembling the buttonholer to see if maybe something is bent, or I am missing something on the installation. At any rate, I just LOVE buttonholes now!