I have ran across a Singer 15-91 on eBay which has been converted to hand crank. It seems to be for a decent price and well within my budget. I have read posts on this forum regarding this machine but not any which have been converted. This brings me to my question. What thickness of veg tan is this machine capable of being that it is converted to hand crank? The seller provided some images of leather the machine has sewn which he claims to be 18oz. It appears to have worked well.
http://www.ebay.com/itm/Powerful-Singer-15-91-Hand-Crank-Leather-Sewing-Machine-Custom-Hardwood-Base-/322580484314?hash=item4b1b4b90da:g:~vUAAOSwbtVZXaKQ