Powering a homemade bandmill
Choosing the right engine for a home-built bandmill. March 20, 2001
I'm having no trouble gathering materials to build a bandmill, except for my powerplant. I picked up an 18 hp Hirth snowmobile engine. Will this do the trick?
If I'm not mistaken, the Hirth is a 2 cycle engine, which rules it out as a serious consideration for this application. The fickle nature of that engine, coupled with the high maintenance, would primarily benefit aspirin production.
You should use the 18 hp engine to start, and if it seems too small, upgrade.
2 cycle engines need RPM to make HP. The engine you're looking at idles at about 1800 RPM and develops 18 HP at about 6000 RPM. 2 cycle engines do not run well when not under a load, so when you're sawing, it's fine, but when you return the blade, the engine wants to overrun because there is no governor!
Also consider cooling. These engines were designed to run in snowmobiles. I have had experience overheating a 292cc Hirth in 30 degree F weather.
I can smell burning aluminum already. Don't waste your time with the snowmobile motor, unless you have a crate of pistons and crank bearings for it. You would be better off with a 4 cycle motor to start with. Older, smaller construction equipment like Ditch Witch trenchers have Wisconsin or Kohler air-cooled motors that can be bought cheap.
Think about a VW motor. It works great on mine (57 HP). They come in 35 to 85 HP, air-cooled and not as heavy as 15 HP ind. kohler.