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

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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