No matter how I tried, I couldn't stop the cut veering to the
right. In the end I just cut out the pieces larger than required
and filed them to shape. The end result was OK but what a waste
of material.

So, what is the technique for hacksawing a straight-ish line
by hand. I guess that as my cuts always went the same way it was
something to do with how I was standing and holding the hacksaw.
Any tips would be gratefully received.

Joe,

Of course, what would be nice for this job would be a high power laser, but I
don't have one either. Lacking such sophisticated tools, we just do the best we
can with what we have. Use a hacksaw blade with a fine pitch, make sure the
blade is tight, and cut at a small angle so more of the blade is guided by the
part you've already cut. (30 degrees good, 90 degrees bad.)

Some kinds of large tin snips are easier to control, but tend to curl the
material more than a saw blade. A nibbling tool is OK for small pieces, but
will quickly wear out your hand.

I've been hacking, punching, snipping and drilling holes in chassis since 1953.

Hope some of that helps.

Doug Moore KB9TMY (Formerly K6HWY)