TALKS BACK
By
Jon Eakes
Lost
of Power
I own an old Delta unisaw, 1725 rpm, 1hp single-phase. It was working great
until this morning when I fired it up and it tried to run but just couldn't
get enough speed, sometimes coming almost to a stop. I checked the switch
contactor and cleaned it and blew it out. It draws in and each line to the
motor reads over 110 and 220 across it so I am assuming that the motor is
getting the right power but I suspect it is in the motor, probably needing
rewinding. What is the correct way to troubleshoot or test the contactor before
I tear into motor? I hate to take it off. It must weigh a ton.
Michael Peck
Michigan
Hello Michael,
Sudden loss of power to a motor could be caused by a number of different problems.
First, you measured the voltage to the motor and found it full voltage. But
it is important to measure that same voltage when the motor is operating.
If the voltage drops dramatically at the switch when you turn on the motor,
there is a supply problem. A drop in voltage might not appear until you put
the saw under load, but then if there is a supply problem, the voltage will
drop as the amperage rises. This is a common problem with the old cartridge
type of fuses: when they half die, they don't let through much amperage.
If all checks on the supply side, then the first and easiest next step is
to pull out the arbour brushes. Most motors have little openings allowing
you to do this without taking the motor off the saw. If the brushes are burned
or misshaped, simply try replacing them. If they seem fine, try measuring
the voltage to the brushes, to see if the switch is not letting the current
through. If the brushes have been in bad shape too long, they might have done
damage to the arbour contacts - and that becomes a job for a re-winding shop.
Full power to both the switch and the brushes - good brushes - and it still
doesn't work? You probably have shorted out windings. Now you can panic.
Jon
Melamine edging
I am trying
to find an iron made for iron-on melamine edging. Also, is there any type
of tape guide for keeping the tape centered while ironing on the edging?
Brian Macklem
Ontario
Hello Brian,
I know of no hand-held speciality iron for melamine, and no manual tape guides.
That is probably because in industry they use taping tables, where the panel
lies flat on a table and slides along to a tape dispenser followed by a heat
head followed by a pressure head and, in some cases, trimming knives right
in line, so everything is always lined up.
It would be easy enough to make yourself a notched pressure block - a piece
of wood with a "T" shaped slot - that could be run right after the
iron to centre and apply pressure to the freshly heated tape.
For trimming the tape, there are many devices made for manually trimming melamine,
some one side at a time, some both at once. The newest and very interesting
is a roller cutter rather than a razor blade, available at Rona.
Jon
Sonic measuring devices
It
is part of our job to inspect boarding homes and at times we need to measure
rooms. We would like to purchase a laser type measuring device that will be
easy to use. What would you suggest is best and easier to use? We currently
own a Zircon Dimensionator. We find it rather unstable and hard to figure
out how it works.
Thanks in advance.
Grace Barrios
Habitat Services
Ontario
Hello Grace,
There are two decent sonic devices on the market: the Zircon Sonic Measure
DM S50L is a simple and reliable little device and has the honesty to shoot
out a circle rather than just a dot. This tells you what is actually being
measured - the average of everything in the circle - and the circle gets bigger
the farther away you get. This averaging feature of all "sonic"
measurers is what makes them appear to be inaccurate and the S50L is the only
one that actually tells you what you are including in your target.
The Strait-Line Sonic Laser Tape is also inexpensive and reliable, but gives
you that misleading little dot. If you have objects closer or farther, close
to that dot, they are probably averaging into the measurements.
The really reliable ones are made by many companies, including Zircon and
Disto and run at around $1,200. They will measure to 1/16 of an inch at a
long distance and can measure to or between rungs of a stairwell, from any
angle. They also have triangularization, meaning you can measure the distance
to the base of a building, shoot to the top, and it will give you the height.
Sonar is cheap, but less reliable. I don't know how the others do what they
do, but their target remains a point, not a growing circle.
Jon
Montreal-based TV broadcaster,
author, home renovation and tool expert Jon Eakes provides a tool feature
in each edition of Home BUILDER.
www.JonEakes.com
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