Michael,
I'm going to take a little different tack here. I know you asked for alternatives to a hacksaw, but sometimes a hacksaw
is the best tool for the job. Don't feel alone if you're having problems cutting with one; judging from my own shop visitors at least 9 out of 10 have trouble. There's both art and technique to using all the fundamental shop tools, but none of them come with instructions.
So, I'm gonna put on my TC hat for a moment and teach.
You need a stout vice on a rigid mount. A good bench vice should be early on your tool list, well before power tools; it does far more than just hold hacksaw work. A rigid mount might be the corner of a heavy bench which is bolted to the wall. Mount the subject material in the vice with the intended cut as close to the jaws as possible to eliminate flex and vibration.
I keep two hacksaw frames hanging near the vice, one loaded with an 18 TPI (tooth per inch) blade for aluminum and the other loaded with a 24 TPI for steel. Two frames is a mere convenience, but you should have both blades. Keep an eye on tooth set (look here if you don't know what "set" means:
http://www.disstonianinstitute.com/glossary.html ). Tooth set is what widens the kerf and allows you to steer the cut. You can't steer if the kerf is the same width as the blade body. Loss of set due to side edge wear is why you replace a properly used hacksaw blade.
The primary error is using a two-handed grip, one on the handle and the other on the far end of the frame. You can neither steer accurately to follow the line (think roll axis) or control the angle at which the teeth meet the cutting surface (think pitch axis). In addition, the extended arm almost guarantees too much pressure on the backstroke, which dulls the blade. A two-handed grip should be reserved for hacking through heavy material (like a solid 1" bar) where accuracy doesn't matter and tooth pressure is spread out across many teeth.
Start the cut by guiding the blade with the thumbnail of your free hand and making a few very light strokes. When you get the cut going, rest that free hand on the bench to steady your upper body.
The root problem for most users is difficulty starting the forward stroke. A tooth catches on the leading edge of the material; the user response is to apply high forward pressure. When the tooth breaks loose, either by cutting or skipping, the resulting stroke is uncontrolled in both the roll axis and the ptich axis.
What you want is a pitch axis that varies throughout the stroke, because it creates a slightly rounded and angled cutting surface where the teeth make contact within the cut. Rock the pitch axis (increase AOA) as you stroke smoothly forward. The result is a cutting surface like you see in the circle below. There is no edge to catch (at "A"):
In addition, the non-flat cutting surface allows each individual tooth full contact, and chips don't raise the teeth off the cutting surface. The result is good cutting with less operator effort. The slight downward motion of your hand will provide all the necessary cutting pressure; don't force the cut. Low effort means the user can stroke smoothly and concentrate on steering the blade in the roll axis. The actual steering is much like the old tailwheel axiom; half as much twice as often.
That's the technique. Like everything else worthwhile, technique plus practice equals skill. You
can cut a perfectly straight line with a hacksaw, and there's a lot of satisfaction in mastering one more fundamental shop skill.
