by Robert Feeser
first appeared in a thread on theWoodNet
woodworking forum. It was compiled and reproduced here for easier public consumption.
Text are the property of Robert Feeser.
This was for
rubber tires on a 14" bandsaw, I believe. Most of it should be equally valid
for the urethane tires, I think.
as part of bandsaw tuning talk given in two sequential meetings of the Greensboro
Woodworking Club in summer, 2005. Note that I probably had only 45 minutes at
REMOVE THE WHEELS
- First, mark
the front rim of both wheels so there will be no confusion about which way
to remount them. Then remove the wheel.
HOW TO MOUNT AND
- The tires can
be stretched over the wheel by hand without much trouble.
- Take the wheels
off the axles first to avoid stressing the machine.
- The tensioning
and tracking mechanism can be broken without too much effort. If the belts
are very hard to get on, it can help to put the rim of the wheel on the
floor, engage the tire first at the top of the wheel, and then press both
sides of the tire down toward the floor, using your weight to help. If
necessary, you can also lever the tires on with screwdrivers like you
do with bicycle tires, but that can cause some minor damage. Immersing
the tire in very hot water for a while softens some tires, making them
easier to stretch onto the wheel.
- The next step
is adjusting the tension so the tire is close to perfectly round to minimize
vibration and other motion.
this can be a tedious affair. I have spent well over an hour on a tire. I
have had difficulty improving the roundness of the tires much with a pair
of urethane tires, but it worked quite well with two pairs of rubber tires
I have mounted.
- The tire is
a rubber or neoprene band stretched around the wheel. When you stretch the
tire onto the wheel you end up with varying tension, and therefore varying
thickness, on different parts of the tire. To get rid of the high and low
spots you have to push and pull the tire around the wheel to redistribute
the tension and the rubber. Place the wheel on the axle and spin it. Watch
the outer edge of the tire and locate the most severe high or low spot. Then
remove the wheel and stretch the tire away from the high spot or toward the
low one with your hands. Then work the edges of the tire down into the groove
in the wheel, making sure it is seated well. Press with your four fingers
against the opposite edge of the tire rather than with your thumb against
the near edge. The four fingers are stronger than the single thumb. Mount
the wheel and spin it again, checking your progress.
- Be patient
and keep at it until the tire is as round as you think you are going to be
able to get it by eye.
- On one tire
I tried to equalize the tension around the tire by inserting a dowel between
the tire and the wheel and then rolling the dowel along the rim of the wheel,
all the way around several times as Mark Duginske's book recommends. I still
had to work high and low spots out of the tire manually. I also tried using
a metal rod instead of the wood dowel; same result. I skipped that step on
the other tire and could not tell that the process took any longer.
- To improve
your ability to locate lumps and dips, clamp a wood stick to the cabinet so
the end comes very close to the crown of the tire. Spin the wheel and keep
tapping the stick in a tiny bit at a time until it just touches the biggest
high spot-you can hear it rub. Remove the wheel and work the high spot out
by shifting the tire away from it slightly in both directions, then check
it again. Keep working at it until you don't think you can get it any better.
Let it rest overnight and then try again.
- When ready
to check roundness, you can measure the amount of runout with a dial indicator.
Mount a wide blade, tension it properly, and position the dial indicator to
touch the side of the blade somewhere where it lays on the tire rather than
to the rubber tire itself. It works better and is more accurate because the
metal blade provides a smoother surface for the tip of the dial indicator,
and it's really the roundness under a properly tensioned blade that counts.
- If there are
significant variations, verify that you are not measuring variations in the
thickness of the blade by turning the wheel several times and noting the position
of the highest point each time. It should appear at the same point on the
wheel each time. If it doesn't, your measurement is being thrown off by uneven
blade thickness or a kink or twist in the blade.
- Lonnie Bird's
book says that a tire out of round by only 0.025 in. will produce a noticeably
HOW TO MOUNT WHEELS
- WHICH SIDE FORWARD?
- Remount the
wheels with the marks you made on the rims to the front.
- If you forgot
to mark the front edge of the wheel, or the mark has disappeared, this may
help. The wheels usually have one or more little balancing divots drilled
in one side-shallow holes drilled with a normal drill to lighten an area of
the wheel's circumference that is heavy. Mount the wheels on the old blue
14 in. Jet bandsaw with the balancing divots facing the back. That's the way
they came on the saw. This is important on the lower wheel-mount that wheel
backwards and it won't turn when the center bolt is tightened-but shouldn't
matter on the upper one.
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