Since I was going to be spending the whole day gluing up slabs for RP
doors, which is boring as hell, I decided to try a test of the idea I
had about using a light bulb inside of the machine cabinets to ward
off condensation and rust. I'm no scientist, having spent my
undergraduate years as a lowly philosophy major, so my testing may not
be up to snuff - I did the best I could. I figured I'd gather up some
data and ask smarter folks what it means.

My shop ain't Dexter's Lab, by a long shot, so I had to work with what
was available to me. Since I was going to be using the tablesaw
during the day, I decided to run the test using the shaper as a test
subject. The tablesaw has a lot less surface area overhanging the
cabinet enclosure and would perhaps respond better to the light bulb
treatment.


Problem: When a cool/dry air mass is followed by a warm/moist air mass
and the transition is somewhat rapid, as sometimes occurs in my area
of Pennsylvania in the Spring and the Fall, condensation forms on the
cast iron surfaces of the stationary machinery, causing rust.

Proposed Solution: An incandescent light bulb, left on overnight,
mounted within the cabinet, may provide enough of a rise in
temperature over the ambient temperature/dew point to eliminate
condensation and rust.

Test Subject: Delta "Platinum Edition" Cabinet Shop Shaper.
Cabinet Enclosu Sheet Metal - 19-1/2" x 19-1/2".
Top: Cast iron - 40" x 27".
Note: Cast Iron Top overhangs Cabinet Enclosure by 10-1/4" on
each side and by 3-3/4" on front and back.

Heat Source: Sixty Watt Incandescent Bulb in Clip On Fixture, mounted
2" away from under side of cast iron top, within cabinet enclosure.

Test Instruments: (1) Amprobe Digital Sling Psychrometer, Model
THWD-1, (2) Unknown Brand Digital Thermometer/Hygrometer (Note: This
was not capable of decimal readout, so all numbers for it are whole),
(3) Aquarium Thermometer, of the type intended to be applied to the
exterior surface of the glass on an aquarium - mounted on the edge of
the cast iron top (Note: this was not tested against the other two
instruments but was put on in an attempt to gauge the actual surface
temperature of the cast iron top - it is only capable of reading out
in two degree increments). The instruments (1 and 2) were sat next
to each other for one hour and gave the same readings (within their
abilities) before the test.

The Test:

The Unknown Brand Thermometer/Hygrometer was left at the workbench and
the Digital Sling Psychrometer was used at the Shaper, which was
approximately 8' away. True surface temperature of the cast iron top
could not be measured with the instruments at hand. The Digital Sling
Psychrometer was laid on it's side, with the sensor approximately 1/2"
above the cast iron surface.

The Digital Sling Psychrometer was positioned in the approximate
center of the area over the cabinet enclosure in Test Position "A" and
was positioned approximately 1" from the edge of the overhanging
portion of the cast iron top in Test Position "B". The approximate
distance between the two test positions was 19". The instrument was
moved from position "A" to position "B' at half-hour intervals.


Results:

At Test Position "A" (center of cast iron top, over cabinet
enclosure).

Hour Temperature/Ambient Temperature/Test Position "A"

0 63f 62.2f
1 63f 67.1f
2 64f 68.2f
3 63f 68.4f
4 63f 68.4f
5 63f 68.7f
6 63f 68.4f
7 62f 67.8f
8 62f 67.2f



At Test Position "B" (approximately 1" from edge of cast iron top).

Hour Temperature/Ambient Temperature/Test Position "B"
0 63f 62.2f
1 63f 63.8f
2 63f 64.3f
3 63f 64.6f
4 63f 64.6f
5 63f 65.0f
6 62f 64.6f
7 62f 63.5f
8 61f 63.9f



NOTE: At the end of the test, the aquarium thermometer, applied to
the surface of the cast iron table, read 68f next to Test Position
"B", when the Digital Sling Psychrometer read 63.9 at Test Position
"B". It read 76f next to Test Position "A" when the Digital Sling
Psychrometer read 68f at Test Position "A".



Conclusion: Damned if I know. I'm hoping that some smart person can
tell from the data if the light bulb idea will work.


Regards, Tom
Thomas J. Watson-Cabinetmaker
Gulph Mills, Pennsylvania
http://users.snip.net/~tjwatson

Hi Tom,

Here's a couple of observations regarding the condensation:

1. A 60 watt bulb will generate quite a bit of heat. It will also die an
early death IF you run it at full voltage. Try a 100 watt bulb, but instead
of connecting it directly to the line, install a 3-amp, 200 volt diode
(Radio Shack P/N 276-1143, $1.39) will work just fine) in series with the
hot (black wire or brass screw) lead. What this does, is only allow 1/2 the
voltage to flow through the bulb. The bulb burns a bit less than 1/2 bright,
and much more red in the spectrum. It also REALLY lengthens life. Had a yard
light that would blow a bulb everytime I hit the post mowing the lawn, or
even if the paper delivery person kinda bumped it with their sack of papers.
I was getting 2 weeks max on a bulb. Installed the diode, bulb was going for
over two years (may still be going, we sold that house and moved). By moving
from a 60 watt bulb to a 1/2 lit 100 watt bulb, you are losing just a little
bit of heating, but the bulb will last longer.

2. Condensation is a problem in many areas. One difficult area was on the
radar indicator on several different classes of Coast Guard Cutters and
small boats. The "old" equipment was full of tubes, and never had a bit of a
problem, but the new solid state radar indicators (well, except for the
cathode ray display) had severe condensation problems. First attempt was to
seal the indicator up ... which fails because when you heat the sealed box,
it's pressure goes up and will blow past the door seals. When it cools back
down ... yep, creates a vacuum which draws in damp air, and the effect is a
very nicely sealed box full of water.

The answer there was to install a heater strip ... looked all the world like
a power resistor, but was designed to conduct heat both to the chassis where
it was mounted, and to the surrounding air. If the light bulb test works and
you want to eliminate the dangers of a broken bulb, you may want to look
further into this possibility.

3. The simplest answer may simply be to get one of those double jointed
drafting table lamps, and simply turn the lamp on and put it close to the
top surface of the equipment you're working to protect. Put a fairly small
bulb (25 watt) and move the lamp real close ... and you'll heat the top
surface. Might need two lamps, but I think they're what ... $8.95 each (
http://www.draftingequipment.com/DEW...ombo&swing.htm )
.... that's the name ... swing arm lamp. This has several benefits ...
first, it's cheap. Second, you can use the lamps in the shop for spot
illumination when needed. Third, you won't forget that you left a lamp on
that's buried inside the cabinet. Fourth, it's cheap. Fifth, you'll be able
to adjust the lamp position for optimal heating (without overheating) ... so
you don't dry out the lubrication on the trunion and tilt assemblages.
Sixth, it's CHEAP!

It sounds like you were measuring the air temperature immediately above the
table, and not the table surface temperature. An infared pyrometer is just
the ticket, but at about $300.00 for a good one ... probably more than you'd
like to spend for a one-shot deal. If you have an electronic thermometer ...
one for cooking (it has a nice wide range as opposed to a digital
oral/rectal thermometer (1) that has a very narrow temperature range) you
can make direct contact with the surface and read the temperature. Mark
several spots on the table surface by circling the area with a pencil, and
measure the temperature at all of these points everytime you need a sample.
Averaging the temperatures will give you an overall indicator ... likewise,
mapping the temperatures will give you a reasonable temperature gradient to
help determine if you are heating a localized spot, or diffusing the heat
throughout.


HTH

Rick



Who will get back making sawdust "Real Soon Now"

(1) I don't EVEN need to go there!


"Tom Watson" wrote
Since I was going to be spending the whole day gluing up slabs for RP
doors, which is boring as hell, I decided to try a test of the idea I
had about using a light bulb inside of the machine cabinets to ward
off condensation and rust.

On Fri, 07 Nov 2003 00:01:12 GMT, "Rick" wrote:

snip
The answer there was to install a heater strip ... looked all the world like
a power resistor, but was designed to conduct heat both to the chassis where
it was mounted, and to the surrounding air. If the light bulb test works and
you want to eliminate the dangers of a broken bulb, you may want to look
further into this possibility.
snip

Thanks, Rick. You gave me some interesting things to think about.




Regards, Tom
Thomas J. Watson-Cabinetmaker
Gulph Mills, Pennsylvania
http://users.snip.net/~tjwatson

"Tom Watson" wrote in message


Problem: When a cool/dry air mass is followed by a warm/moist air mass
and the transition is somewhat rapid, as sometimes occurs in my area
of Pennsylvania in the Spring and the Fall, condensation forms on the
cast iron surfaces of the stationary machinery, causing rust.

Damned right rapid. One fall day I had the garage door open under those
circumstances. Cool from the last couple of days, then a farm front with
high humidity. I could see the rust forming on the table top from front to
back right before my eyes. I grabbed nearby paper towels and could not stop
it.

That is the day I decided to change from wax to Top Cote.
Ed

Tom:

My TS got clobbered a couple of months ago when my 4 year old hot water
heater farted. It spewed 100 + degree water for a hour or two. The damage
was minimal from the water but the condensation went to work immediately and
rust set in soon after. To thwart the hot water heater farting at me again I
am going to have a pan installed with an automatic shutoff that is triggered
by a float.

In cleaning up my shop A dehumidifier worked wonders in reducung the
moisture. Would it not work in your situation?








"Tom Watson" wrote in message
...
Since I was going to be spending the whole day gluing up slabs for RP
doors, which is boring as hell, I decided to try a test of the idea I
had about using a light bulb inside of the machine cabinets to ward
off condensation and rust. I'm no scientist, having spent my
undergraduate years as a lowly philosophy major, so my testing may not
be up to snuff - I did the best I could. I figured I'd gather up some
data and ask smarter folks what it means.

My shop ain't Dexter's Lab, by a long shot, so I had to work with what
was available to me. Since I was going to be using the tablesaw
during the day, I decided to run the test using the shaper as a test
subject. The tablesaw has a lot less surface area overhanging the
cabinet enclosure and would perhaps respond better to the light bulb
treatment.


Problem: When a cool/dry air mass is followed by a warm/moist air mass
and the transition is somewhat rapid, as sometimes occurs in my area
of Pennsylvania in the Spring and the Fall, condensation forms on the
cast iron surfaces of the stationary machinery, causing rust.

Proposed Solution: An incandescent light bulb, left on overnight,
mounted within the cabinet, may provide enough of a rise in
temperature over the ambient temperature/dew point to eliminate
condensation and rust.

Test Subject: Delta "Platinum Edition" Cabinet Shop Shaper.
Cabinet Enclosu Sheet Metal - 19-1/2" x 19-1/2".
Top: Cast iron - 40" x 27".
Note: Cast Iron Top overhangs Cabinet Enclosure by 10-1/4" on
each side and by 3-3/4" on front and back.

Heat Source: Sixty Watt Incandescent Bulb in Clip On Fixture, mounted
2" away from under side of cast iron top, within cabinet enclosure.

Test Instruments: (1) Amprobe Digital Sling Psychrometer, Model
THWD-1, (2) Unknown Brand Digital Thermometer/Hygrometer (Note: This
was not capable of decimal readout, so all numbers for it are whole),
(3) Aquarium Thermometer, of the type intended to be applied to the
exterior surface of the glass on an aquarium - mounted on the edge of
the cast iron top (Note: this was not tested against the other two
instruments but was put on in an attempt to gauge the actual surface
temperature of the cast iron top - it is only capable of reading out
in two degree increments). The instruments (1 and 2) were sat next
to each other for one hour and gave the same readings (within their
abilities) before the test.

The Test:

The Unknown Brand Thermometer/Hygrometer was left at the workbench and
the Digital Sling Psychrometer was used at the Shaper, which was
approximately 8' away. True surface temperature of the cast iron top
could not be measured with the instruments at hand. The Digital Sling
Psychrometer was laid on it's side, with the sensor approximately 1/2"
above the cast iron surface.

The Digital Sling Psychrometer was positioned in the approximate
center of the area over the cabinet enclosure in Test Position "A" and
was positioned approximately 1" from the edge of the overhanging
portion of the cast iron top in Test Position "B". The approximate
distance between the two test positions was 19". The instrument was
moved from position "A" to position "B' at half-hour intervals.


Results:

At Test Position "A" (center of cast iron top, over cabinet
enclosure).

Hour Temperature/Ambient Temperature/Test Position "A"

0 63f 62.2f
1 63f 67.1f
2 64f 68.2f
3 63f 68.4f
4 63f 68.4f
5 63f 68.7f
6 63f 68.4f
7 62f 67.8f
8 62f 67.2f



At Test Position "B" (approximately 1" from edge of cast iron top).

Hour Temperature/Ambient Temperature/Test Position "B"
0 63f 62.2f
1 63f 63.8f
2 63f 64.3f
3 63f 64.6f
4 63f 64.6f
5 63f 65.0f
6 62f 64.6f
7 62f 63.5f
8 61f 63.9f



NOTE: At the end of the test, the aquarium thermometer, applied to
the surface of the cast iron table, read 68f next to Test Position
"B", when the Digital Sling Psychrometer read 63.9 at Test Position
"B". It read 76f next to Test Position "A" when the Digital Sling
Psychrometer read 68f at Test Position "A".



Conclusion: Damned if I know. I'm hoping that some smart person can
tell from the data if the light bulb idea will work.


Regards, Tom
Thomas J. Watson-Cabinetmaker
Gulph Mills, Pennsylvania
http://users.snip.net/~tjwatson