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| Heat blanket burn out... http://luthiersforum.com/forum/viewtopic.php?f=10101&t=38976 |
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| Author: | meddlingfool [ Thu Jan 17, 2013 12:43 am ] |
| Post subject: | Heat blanket burn out... |
Can you burn them out? I've lost 7 sides in a row using standard practice, different species, random spots. About 6 months ago, the timer/router controller stopped working, so I've been plugging the blanket straight into the wall. Sometimes it takes forever to get to temp, sometimes faster, sometimes going backward a while before getting hotter again. I also think it has hot/cold spots. Do these things pooch out? I doubt if I've even bent 70 sides since getting it about 2 1/2 years ago.... |
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| Author: | bluescreek [ Thu Jan 17, 2013 8:00 am ] |
| Post subject: | Re: Heat blanket burn out... |
They can . Get a controller , as these things can spike to 450 degressF. I burned 2 up in 8 years. The blanket didn't burn up the cord failed. I will not use Full power more than a few minutes. Not all blankets are created equal, some are only 2 1/2 watts per inch . I use 5 watts per inch. Early in my days I tried a 2 1/2 and it didn't last long and at that time I was bending thicker than I should. It lasted less than a year. Been using 5 watters ever since. With a little care they should last you a long time. Simple rules to follow for caring of the blanket 1 don't fold it. I keep mine in my machine when not in use 2 don't over heat it. Use a controller 3 avoid light dimmer switches they use a resistor , this lowers the voltage and makes the blanket work harder and will burn them up much like a low voltage to a motor. 4 Keep an eye on the plug wire getting bare spots. 5 don't run on Full power more than 6 min . |
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| Author: | TonyKarol [ Thu Jan 17, 2013 10:54 am ] |
| Post subject: | Re: Heat blanket burn out... |
Most cheap dimmers use a chopper circuit to reduce voltage ... the peak is still 120V, but the sine wave is chopped up into intervals to give a lower RMS output .... a resistor would get way too hot and need to be rated at a high wattage - not practical. I have been using a 2.5 watt Omega blanket with a cheap HD dimmer for almost ten years now .. still working fine. |
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| Author: | Mattia Valente [ Thu Jan 17, 2013 10:55 am ] |
| Post subject: | Re: Heat blanket burn out... |
John - by 'controller' you mean a PID with a servo switch (on/off voltage) type setup? |
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| Author: | Joe Beaver [ Thu Jan 17, 2013 6:24 pm ] |
| Post subject: | Re: Heat blanket burn out... |
In my experience most of those crazy temperature fluctuations are do the temp reading apparatus. I am forever cautious so I use water as an indicator. (look for steam, listen for water sizzle and drop a little water on the slats to see what it does) |
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