Advanced Questions

What about hydraulics?  They are a wonderful invention transmitting power (piston or motor) anywhere you can run a hose.  My "Scissor Lift" couldn't work without them.  The large hydraulic sawmills are interesting to watch, logs lifted, loaded, clamped, cut and turned by an operator sitting in a lawnchair under an umbrella with a beer, pushing buttons.  Of course you'll still need to get the logs to the mill and you'll need at least one other person to remove the boards.  If you're running a large commercial operation, then this is the only way to go.  But, for a small one man hobby operation, they are impractical.  The cost of the hydraulics alone (pump, spool valves, cylinders, motors and hoses) could be more than the whole rest of the mill.  Hydraulics take power and require a larger engine, therefore bigger, heavier (expensive) mill, etc....

What is the difference between "I" and "C" frame power heads?  Just as the letters look, an "I" frame is a straight "bar" with the bandwheels at either end.  A "C" frame is like the traditional shop band saws with the bandwheels at the ends of the "C", to give a larger "throat" and a greater cutting depth, necessary for shop use but requiring a stronger heavier frame as a "C" frame is weaker by design.  Not being engineers, sawmill builders took the shop bandsaw design (that they knew) and turned it on its side.  This is unnecessary in a sawmill.  You don't need this "deep throat" to cut boards from the top down.  Their mills could actually cut the bottom of the log in the first cut which would be ridiculous, of course.  This unnecessary "ability" comes at a cost, and the powerhead must be bigger and heavier, etc.. 
When I designed his first "I" frame in the Model I, all the major sawmill manufacturers were using the cumbersome "C" frame design.  Since his first website showed the Model I in the mid '90's some manufacturers have started using the "I" frame design in their mills too.

 

What about purchasing blades?  Most sawmill manufacturers supply blades for their mills and you buy from them.  With a homebuilt mill you may check the Yellow Pages under Saws or Google "bandsaw blades" to find the name of a blade supplier near you, so that you can buy direct.  By setting up an account or with a credit card you just call and most suppliers will ship the blades to your door in a few days.  A popular blade for small mills is the Lenox Woodmaster "C", 1 1/4" wide X .035" thick and a 1.1 set.

 

What is the optimum blade speed?  The best blade speed, measured in feet per minute or fpm depends on a number of factors including the type and thickness of the wood, whether it's frozen, motor horsepower, etc...  More speed requires more power but too much speed can cause excess friction and bandwheel vibration.  Too little speed takes too long to cut through the log and you could be wasting power.  With a 13 hp motor, 19" bandwheels and a 4 1/2" motor pulley at 3600 rpm the blade speed will be 4265 fpm, a good compromise.
Since Mr. Sawmill is so efficient  (the motor directly drives the bandwheel) I use a 4 3/4" pulley (i.e. centrifugal clutch) for a blade speed of 4,500 fpm with excellent results.

 

Do I Need A Centrifugal Clutch?  The industrial centrifugal clutch that I use costs $300 and a simple pulley costs about $20.  If you want the blade to be stopped with the motor idling then you must either use a centrifugal clutch or design a motor engagement system where the motor (or an idler pulley) moves to loosen and tighten the drive belt.  This puts more wear on the drive belt as it slips during engagement.  It is possible to use just a fixed motor and pulley (the simplest design) but the blade will be turning all the time.  Some may consider this more dangerous, turning and clamping a log beside a running blade but it's not as bad as it sounds.  The blade is moving slowly, only a small part is exposed and with shorter logs you can be more than six feet away.  It's still far safer than any chain saw.
You could try that out and see how safe you feel with it, knowing that it's a simple job to change to a centrifugal clutch later.  Since most motors are so easy to start (one pull) you could just turn them off.  You'll be starting the motor with the blade engaged but it's not that difficult.  You will put more wear on your pull start mechanism though.

"New knowledge lets you think you know more than you do because you now know more than you did."  David Huggett