Hey, Denny
I bought the Singer 15-88 ... you can see it
Here It wont handle shoes or saddles ... that's a whole other setup ... but it's perfect for leather! It was built in Scotland in 1949 and is in mint condition!
PS - I dunno about the carbide bit size ... it came with the kit and I think I bought the kit from Chevy Duty (?) ... I don't recall.