Description of the Dunmyer Sawmill
The mill was originally a Knight, made before 1900. The carriage is very crude compared to more-modern mills, consisting of 3, 3-wheel trucks, connected by only the setworks shaft at the rear. I added an angle-iron tie bar at the front. The carriage was originally moved by a rack & pinion arrangement, but was converted to cable/drum drive by the previous owner.
In turn, I converted the crude mechanical drive arrangement to a home-brew hydrostatic setup using a Char-Lynn motor, bulldozer pump, 15HP electric motor, and a simple open-circuit valve. The spool has had the edges of the lands ground off a bit to create some leakage as the valve is moved from neutral; this gives a smooth, controllable action. A selector valve on the power unit outside sends the oil to the log splitter as needed. An electric heater element warms the oil in extrememly cold weather.
The mandrel was of the babbet-bearing style when I got it. I made a new one that uses standard 2 15/16" ball bearings. The bearing housing is a bit high, but it doesn't interfere with the sawing. It saws much better with a cool mandrel and 6" collars!
Power is provided by a 62HP Case 509 Power Unit. The engine is the same as in a Case 500/600/900 Diesel tractor. It has a wet, over-center style clutch. I completely overhauled the engine when I got it in 1976, including a total rebuild of the fuel system. That actually cost a bit more than the rest of the job put together! It runs like a million bucks, but is very cold-natured due to the 15:1 compression ratio. It is also a bit light on power, 100+ HP would be nice.
The multi-belt reduction drives a 1:1 ratio right-angle gearbox that is direct-coupled to the mandrel through a chain coupling. Direct belt reduction to the mandrel wouldn't work because it'd turn the wrong way.
The saw itself is a 55" (we have 3 blades, up to 60" diameter) inserted-tooth type, Style 'B', with 36 teeth. It runs at about 500 RPM. We sharpen it with a 'Jockey' brand grinder until the teeth ('bits') get too worn, at which time we replace them. It costs about $.70/tooth, and no, they're not Carbide.
The sawdust drag is a simple corn-picker chain driven by a 1/3 HP single-phase electric motor and worm gear reducer. It runs at perhaps 60 FPM, and simply drags the sawdust out onto a pile behind the building. The chain goes around a sprocket outside, then is carried on a "bridge" back to the building, entering under the eaves. It slides in a wooden channel to the drive sprocket at the top of the vertical run. The chain continues straight down, around the sprocket in the pit, then out under the saw to drag the sawdust away. Simple, low power requirements, and pretty trouble-free.
There are 3 skidway beams, 6" X 8" in size. The logs are set on the skidway with the forklift (or HiLo as we call it), then rolled up to the carriage with Cant Hooks. Large logs are LOTS of work, but average saw logs of 16" dia X 10' or 12' long roll quite easily.
There are "dogs" on the carriage, attached to the "head blocks", which in turn slide on the "bunks". The log lays on the bunks, is held in place with the dogs, and pulling the setworks handle advances the log towards the operator (and the saw!) by sliding it. There is no taper attachment as most mills have; we just use a 1" or 2" board between the headblock and the log.
The mill was originally set on wooden beams, but we built a track out of 2" pipes, one on top of the other, stitch welded together.. It's not the best, but was what I had available at the time. The entire thing sits on piers built from 12" concrete block set on footers with the cores poured full.
Sawed lumber is put on a "lumber buggy", which is an old wagon gear that we push in and out of the building. It works well, allowing a single man to handle pretty heavy lumber because he only has to pick up one end at a time. After pushing it out, we come in from the side with the HiLo and pick up the entire stack.
Slabs and edgings are put onto the "slab buggy", a little railroad car arrangement with wooden bunks and stakes on it. It's about 36" wide, by 10' long. We push it outside when it's full, then use a Stihl chainsaw (is there any other brand?) with a 60" bar and helper handle to cut the slabwood into 18" long pieces. It then gets stacked on pallets; a 48" pallet holds exactly a half-cord when stacked 4' high. It won't fit on a pickup if you just throw it on, you must stack at least a third of it first.
The building is 24' X 60' and is mostly built from lumber sawed on the mill. The trusses and roof purlins were store-bought. There's 115 volt single-phase and 480 volt 3-phase power in the building, most of it run in rigid conduit salvaged from my workplace. The building sits on concrete piers poured in 5-gallon cans stacked 2 or 3 high. The posts are mostly untreated, as they don't actually contact the ground.
The HiLo (forklift truck) is built on an International I-4. This is the Industrial version of a Model 'H' tractor, with heavy-duty "rear" axles and a wide "front" axle. The differential assembly is installed upside-down, giving it 5 speeds forward and 1 reverse, in a 'backwards' direction. I changed the mast assy. to one that was in a bit better shape and shorter than what was on it when I got it. It'll just barely enter a 7' high doorway. I also added a flow divider to the hydraulic system and an Orbitrol steering unit. The electrical system was 12 volt when I got it, using a GM alternator. We've not yet gotten around to overhauling the engine, and it is TIRED. We did go through the driveline, from the clutch back.
Two men can saw about 1000 bf in a day, even taking time to cut (but not stack) the slabwood. We don't work a full day, usually about 4 hours of actual sawing. We don't buy much timber, doing mostly custom sawing for local farmers and woodworkers. There are nearly no other mills in the area, with the exception of a couple of guys with the little WoodMizer bandmill type setups.
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