This is a horizontal bandsaw. It's usually used to cut stock to rough length, but with a couple of tricks and a bit of finesse you can use it to cut accurately (within a few thousands) again and again.
Step 1: Measure and Mark the Workpiece
First, measure and mark your workpiece. Using a little Dykem Blue makes the scribed line a lot easier to see, but isn't absolutely necessary. Use whatever tool is appropriate to mark the desired cut line. Here, I use a digital height gauge and make a mark at one inch from the end.
Step 2: Safety First
Return to the machine and make sure the emergency stop is activated (pressed in) and the feed rate is set to zero. People like to leave these active after using the machine. On the TechShop saw, the feed control knob is located on the top of the machine.
Step 3: Insert the Workpiece Into the Horizontal Bandsaw
Lift the bandsaw head by the red handle until there's enough clearance for the workpiece to fit. Lightly secure the workpiece in place by sliding the moveable jaw of the vise against it. Don't clamp it into place yet, we'll need to slide it back and forth to locate the cut accurately. Loosen the blade guide and move it as close as possible to the workpiece. Dont' move the guide so far in that it will impact the workpiece as it drops, however. If the guide is too far out, you might not get a straight cut, but it isn't worth risking damage to the machine.
Step 4: Prepare for Positioning
With the feed rate set to zero, disengage the emergency stop (twist the knob counter-clockwise until it pops out). Press the feed button and turn the speed knob to lower the bandsaw head. Keeping an eye on the rate of descent, lower the blade until it's just above the workpiece. Re-engage the emergency stop and set the feed rate back to zero.
Step 5: The Trick
The emergency brake is on and the feed rate is zero, right? Double check. Now, using a laser pointer, cast a shadow of the blade onto the workpiece. You'll need to move the laser forward and back until it's centered on the blade and angle it until the shadow is at its minimum thickness. The laser light should be just glinting of the protruding teeth of the blade. If you can see a solid line on the side of the blade, you you need to tilt the pointer more (or less). Slide the stock in and out until the edge of the shadow lines up with the scribed mark. Clamp the workpiece in position using the hand wheel, re-measure, and you're ready to cut.
Step 6: Make the Cut
Lift the bandsaw head up about a half inch to an inch. Disengage the emergency stop. Check to make sure the feed rate is set to zero (see a pattern here?). Finally, press the power button. The blade should start turning and the coolant pump should engage. With the blade turning, walk around to the speed control and set the speed to an appropriate rate. Our bandsaw includes a handy dandy reference chart which says to cut aluminum at 350. Check to ensure the coolant is coating the blade and turn the feed control to the desired feed rate, also included on the chart.
At this point, the head will start dropping and, once the blade touches the material, the machine will start cutting. Keep a hand near the emergency stop in case something goes wrong - you did tighten the vise, right? - but don't hit it unless necessary. The machine will turn itself off once it's finished cutting. Once the blade stops turning, hit the emergency stop and pick up your cut piece. Be careful, the cutting process leaves a razor sharp burr on one side. You'll want to knock this down with a file or bang the burr on a metal surface to flatten it.
Step 7: Check for Accuracy
Let's see how we did. A half-thousand off? Sorry guys, I tried. Still, not bad for a machine designed for rough cuts.
And, as always, I made it at the TechShop.