Arnold Howard on sun 25 jul 99
I have three suggestions for checking and replacing kiln elements:
1. Buy a 10 ohm resistor from Radio Shack to calibrate your ohm meter.
The resistor is less than a dollar.
Place the leads of the meter on the wire ends of the resistor. Adjust
your meter until it reads 10 ohms.
2. When checking the resistance of an element, first unplug the kiln.
Place the leads of the ohm meter against the two element connectors of
the element you are testing. Make sure you have good contact between
the ohm meter leads and element connectors.
There is no need to remove an electrical wire from the connectors,
provided you have only one wire attached to each element connector. If
you have more than one lead wire on a connector, it may mean that your
elements are wired in series/parallel, and you could get a wrong
reading. (Current from the ohmmeter can pass through other elements
than the one you are testing.)
3. When replacing an element, line the bottom of the kiln with
newspaper to avoid getting kiln wash on the new element.
I would enjoy hearing suggestions from others on replacing elements.
Thanks,
Arnold Howard
Paragon Industries, Inc.
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Arnold Howard on tue 27 jul 99
(See note below)
--- "Christopher J. Anton" wrote:
> > I have three suggestions for checking and
> replacing kiln elements:
> >
> > 1. Buy a 10 ohm resistor from Radio Shack to
> calibrate your ohm meter.
> > The resistor is less than a dollar.
> >
> > Place the leads of the meter on the wire ends of
> the resistor. Adjust
> > your meter until it reads 10 ohms.
> >
> Just out of curiosity ( being an old electronics
> tech) Is there a reason why
> you recommend the use of the resistor vice shorting
> the leads and adjusting
> for zero ohms?
I should have been more specific. After connecting leads to the 10 ohm
resistor, adjust the meter to 10 ohms.
One reason we recommend calibrating the meter with the resistor is that
it helps someone with an unfamiliar meter to find the correct switch
position on the meter.
>
> (as a side note, the calibration mentioned applies
> to analog meters with
> needles. Digital meters should not need the
> calibration)
>
> - Chris
>
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Christopher J. Anton on tue 27 jul 99
> Who ever wrote this needs to clarify their data.
>
> I will explain. That cheap resistor would be + or - 20% tolerance. That
> means it could be 8 to 12 ohms and you suggest calibrating a meter to it?
> If you plain on calibrating a meter, I would obtain a precision resistor.
>
> And unless you have an antique meter, it has no adjustment.
The resistor the original suggester refered to was probably RadioShack
catalog number 271-151, a two-pack of +\- 5% tolerance 10 ohm metal oxide
resistors. 1% tolerance resistors may be ordered through RadioShack's
direct order program (RSU) using catalog number 113454477. I was not able
to find any 20% tolerance resistors in RadioShack's catalog. In fact,
standard resistor coding allows for 1% (gold stripe), 5% (silver stripe), or
10% (no precision stripe).
Any analog meter (meter movement v. digital display) should have an
adjustment capability. The need for this is inherent in the design of the
D'Arsonaval (sp?) meter movement support circuits. I have yet to see any
new analog multimeters which did not have a zero adjust capability.
I hope this helps clarify things.
- Chris
Arnold Howard on tue 27 jul 99
Sam, thanks for your comments on ohmmeter calibration. (See Sam
Shuford's letter below.) It sounds like you are an electrician.
Calibrating the ohmmeter before reading element resistance demonstrates
that the meter (including digital meters) is probably less accurate
than you thought. This is useful to know, because some people worry if
their resistance reading is off by an ohm or two.
If you are using the 10 ohm resistor on a digital meter, note how far
off your meter is. Then add or subtract that number of ohms when
measuring the element.
The 10 ohm resistors I buy from Radio Shack are rated to 5% tolerance,
which is close enough for measuring elements. Great accuracy is
unnecessary, because the purpose of measuring element resistance is not
to determine element wear. After all, the difference in resistance
between a new and a worn element is difficult to measure with an ohm
meter. Length of firing time is a better indicator of element wear.
So why measure element resistance?
To make sure the elements are the correct ones for your kiln. If
resistance is way off, you know something is wrong.
Also, the ohmmeter will tell you if you have a burned out element.
If anyone disagrees, please let me know. Open dialogue promotes
learning.
Thanks,
Arnold Howard
Paragon/ Mesquite, Texas
"Sam Shuford" wrote:
"Who ever wrote this needs to clarify their data.
"I will explain. That cheap resistor would be + or - 20% tolerance.
That means it could be 8 to 12 ohms and you suggest calibrating a meter
to it? If you plain on calibrating a meter, I would obtain a precision
resistor.
"And unless you have an antique meter, it has no adjustment. For a
small amount you can buy a digital meter from radio shack with a lot
better accuracy that that cheap resistor.
"YES I KNOW, THERE ARE A LOT OF SIMPSON 260's and other fine old
equipment, but anyone having one would know its limitations and how to
calibrate it."
Sammy J. Shuford
Samshuford@cchat.com
-----Original Message-----
Arnold Howard wrote:
"Subject: A pointer on element replacement
"I have three suggestions for checking and replacing kiln elements:
"1. Buy a 10 ohm resistor from Radio Shack to calibrate your ohm meter.
The resistor is less than a dollar.
"Place the leads of the meter on the wire ends of the resistor. Adjust
your meter until it reads 10 ohms."
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