I built one like this with a 10hp Tecumseh 3 years ago. I never really got it working well - the carriage always started swaying and it would throw the chain. For one, I built the carriage too high and not nearly beefy enough. I definitely didn't consider it slow by any means though and it was unstoppable even with heavy .404 chain (until it threw the chain, anyway). I think I may give it another shot this summer though, as my welding and fabricating skills have gotten MUCH better since then. The welder I built it with was just a 150 amp Ford alternator belted to the same 10hp engine. It worked OK but I have a proper welder now. I wouldn't mind seeing a closer view of that jackshaft system on the one posted above though, as mine really could be improved upon. Does the whole powerhead raise and lower, or does the sprocket float on the jackshaft and just the bar moves?