First check blade weld and make sure it is straight. Next check the rubber
tires. They should have a slight crown. If it has worn flat you need new
tires. Sort of counter intuitive but the blade seeks the high spot as it is
running. Next check the wheel alignment. Both wheels should be parallel
and in the same plane. Lay a straight edge against both wheels. It should
touch the top and bottom rim of both wheels. If not there should be a set
screw or bolt next to the top wheel axel that adjust the angle and the
powered wheel can be slipped in or out on its shaft.

The blade tension should be just tight enough that it makes a musical note
when plucked and it is good practice to back off the tension when the saw is
not being used.

The Bandsaw Book by Mark Duginski is primarily aimed at wood cutting
bandsaws but the tuning chapter applies to both wood and metal.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Chris" wrote in message
...
I feel an idiot for not being able to get this damned thing fixed myself,
but I have a smallish bench mounted metal cutting bandsaw of good quality.
OK, she's done a bit of work before I got her, but there's no wear in the
bearings and the cast iron wheels run true. I have played with blade
tension (tighter seems more reliable) and with the top (none powered
wheel)
tilt, which is adjustable, and the blade guide ball bearings, which are
adjustable, but STILL the blade will suddenly jump off one of the wheels.
3
things look less than perfect. the wheels had some sort o gritty coating,
when new, like coarse carborundum paper, this is now quite worn. The blade
makes a noticeable jump as the welded part passes through the work piece.
Nothing much, but when worked hard it is audible and can be felt. Finally
the blade is quite old and not as sharp as it might be. Cutting alloy
makes
the blade come off more than steel.. Can anyone with experience of these
machines point me in any directions to look to? Thanks!