HomeRoast Digest


Topic: digital thermometer (14 msgs / 329 lines)
1) From: Richard Curits
Scott,
You mentioned that you have just started using a digital thermometer to 
monitor the progress of your roasts.  Where did you find it, and how long is 
the probe?  I found one that had a 4" probe, but I'm wary of sticking it 
down through the top of my HWP, because the plastic handle at the end of the 
probe would get fried.  Do you use that with your HWP?  If so, where do you 
insert it?
Thanks, Richard
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2) From: Ed Needham
I enlarged one of the holes in the top for my digital probe.  It has not
caused a problem.  I try not to insert the probe all the way, because it can
damage the inner workings of the probe according to the directions with my
unit.  The tip of my probe is just below the height of the deflector in the
HWP.  Seems to work well there for me.
Regards,
Ed Needham
ed

3) From:
It's an Extech, I bought it from Graingers, they have a web site I believe.
There should be a store in most large cities.  I bought a Fluke 10" probe to
go with it, although it came with a thermocouple wire which works quite well
hung down into the beans.  I haven't used it with my HWP, I used to use a
dial thermometer, just haven't used my HWP since I got the new digital.  I
just enlarged one of the air holes in the lid and stuck the stem down into
the beans.  There have been several on ebay, snap-on makes a nice one too.
And they are guarenteed for life, so if you happen to get one that doesn't
work just find a Snap-on truck and exchange it for a new one!
Scott

4) From: Rick Farris
I got my $19.95 digital thermometer from Webtronics today.  I ordered it
yesterday afternoon and received it this afternoon.  Of course, I live in
Arizona and am only a few hundred miles away.
It's not very accurate, but more accurate than the mechanical
thermometers -- maybe +/- 9 degrees at 450 degrees.  Plenty good for
roasting coffee.
I immediately roasted up a batch of coffee for my new Moka pot.
Oh...speaking of Moka pots, I used my instant reading thermometer a couple
of days ago to monitor the temperature of the outflow of my Moka pot.
Someone here had claimed that the beginning of the flow from the Moka pot
was considerably cooler than boiling.  Whoever it was, I don't know what
you're smoking, but I want some.  :-)
Most likely, the person doing the measuring was using a high-mass, non
instant-reading thermometer, and were observing the effect of their
thermometer warming up.  When I measured it, the very first drib of coffee
was right at boiling.  But anyway...
I intended to run my first roast with the new thermometer in parallel with
the old (mechanical) one.  Unfortunately, the thermocouple probe (naked
junction, by the way) wouldn't fit through one of the vent holes in my HIP.
I had already reamed out an existing hole for my mechanical thermometer, so
I used it.  That meant that I couldn't use both thermometers at once.
Before my next roast, I'll ream out another hole large enough for the
thermocouple.
The temperatures I observed for 1st and 2nd crack were close to the
previously measured temperatures with the mechanical thermometer.  I did
have a very difficult time keeping my probe in place.  The problem was a lot
like trying to unlock a car using a coat hanger to pull up the lock.  I'm
not sure how I'm going to get around holding the probe wire constantly.
Those of you that just got your new DTMs: I'd like to hear your ideas.
So...I recommend the digital to anyone.  It's both more accurate and cheaper
than the BBQ-style mechanical thermometers I've been using.  OBTW,
Webtronics included a free gift -- a 10-piece set of jewelers screwdrivers!
If the $20 DTM isn't accurate enough for you, Webtronics also has very good
prices on the Fluke Model 50 Series 2.  $169 for the one-input model and
$219 for the two-input version.  Both with 500-point datalogging
capabilities.
-- Rick
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5) From: Fulton Martin
--On Friday, November 01, 2002 11:04 PM -0700 Rick Farris 
 wrote:
<Snip>
An even better deal is the Extech 421508, which includes two (k-type) 
probes and an optically coupled RS232 interface for ~$159. I don't 
remember where I got mine, but here's a link 
. You can even get 
NIST certification for $65 more...
Fulton Martin
__=o&o>__
fulton
San Diego, CA
N32 43.956, W117 05.874
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6) From: Rick Farris
I said:
<Snip>
Fulton replied:
<Snip>
The Fluke has both those features -- I forgot to mention them.  On the other
hand, after searching OmniControls, I was mistaken about the Flukes having
datalogging for $210.  A dual-input Fluke 54 w/datalogging is $319.
(Single-input $249)
The price has come down on the Extech, it's now $159.  A dual-input Extech
with datalogging (422130) is $219, and includes 8000 points as opposed to
the Fluke's 500.
Geez, I guess I'll have to investigate Extech.  Do any of you
process-control types  have experience with Extech?  I know that Fluke is a
bastion of support and reliability.  How about Extech?
-- Rick
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7) From: dewardh
Rick:
<Snip>
process-control types  have experience with Extech?
Extech has been around for a while, but it's not the same company that it used 
to be (as far as I can tell from their current catalog).  I've got a couple 
Extech "handhelds" from their now discontinued "Oyster" series (the line 
survives only in pH/ORP meters . . . guess those didn't sell very well so they 
still have some left) . . . and still use the RTD thermometer regularly 
(including for bean temp when roasting ), but the thing is so old it doesn't 
even say "made in someplace else" on it.  No doubt everything they sell today 
is made "there" (wherever "there" is), and is no better (or worse) than 
anything else from "there".  Just like Fluke.  Anyway . . . they used to also 
have a line of industrial controllers that seems to have "bit the dust" (it's 
hard to beat Omega in that market).  Since Grainger now carries what appears to 
be the whole Extech line it probably makes sense to buy there . . . that way 
you have Grainger's guarantee to fall back on, should you need it (the 421508 
is $159 at Grainger also).  There is a "new" model coming out (according to the 
Extech web page) that looks a bit better (the EA15) but it remains to be seen 
how it's going to be priced.
It all depends on what you want to do.  A 421508, a laptop, some mechanism to 
control the heater and some Basic or Java code, and you'd have the controller 
for an "automated" profile roaster.  Two cheap thermemeters, a timer, a variac, 
and a few minutes attention to each roast and you'd have a "manual" profile 
roaster that would do the exact same thing but with more flexibility (and it's 
"on-the-fly field re-programable" ).
Someday, I suppose, every room in every house will be "listening", and you'll 
be able to say "turn out the light in fifteen seconds" as you leave the room, 
and it will happen.  I expect for the rest of *my* life to just flip the 
switch, though . . .
Deward
Ps.  don't *even* tell me about those things that already turn the lights off 
"automatically" when you leave the room . . . they've got those at my wife's 
new office, and they turn the lights off when she's sitting quietly at her 
desk, too . . . (she, like me, just wants a switch . . . but they don't have 
those any more . . .).
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8) From: Mike Gallant
On Saturday, Nov 2, 2002, at 19:09 US/Pacific, dewardh wrote:
<Snip>
	So, is the serial protocol the 421508 uses public? I did a quick 
google search, and didn't find anything.
-mike
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9) From: dewardh
Mike:
<Snip>
Well . . . I don't own one, but the data sheet at the Extech site says it comes 
with a "manual with QuickBasic PC communication program" . . . and that would 
mean that the code is all exposed.  There wouldn't be much point in 
implementing a built in RS-232 interface without a means to access it . . .
You could always call their tech support number if in doubt . . .
Deward
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10) From: Mike Gallant
<Snip>
	Didn't see that. I assumed there would be some way to access it (I'm 
slow, but not quite that slow :) - I just thought it might be only with 
some proprietary Extech software.  		
	Thanks for the info.
-mike
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11) From: Rick Farris
Mike:
<Snip>
It's been my experience with equipment like that that the instrument will
probably have a mode (the default one, most likely) where it sits there and
spits out an ASCII string every time it takes a reading.  Something like
this:
   10/16/2002 21:46 443 076 367  (Date Time T1 T2 T1-T2)
Or some slight variation on that.  It will probably have a mode (they
mentioned "bi-directional") where you can turn off the automatic updates and
send it a command to return a reading.  I don't expect any special serial
"protocol" other than RS-232.  (Yes, yes, I know that RS-232 is not really a
protocol.  By "RS-232 protocol" I really mean "something that a 16450, or
it's ilk (8250, 16550, ...) will recognize")
-- Rick
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12) From: Mike Gallant
Good info. Thanks Rick.
-mike
On Saturday, Nov 2, 2002, at 21:40 US/Pacific, Rick Farris wrote:
<Snip>
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13) From: Andrew Thomas
I too got one of the 19.95 thermocouple thermometers from Circuit Specialists. Here are some of the things I've discovered:
When I checked for accuracy in boiling water, I got a reading of 211 degrees F. That may be spot-on here at about 1000 ft. elevation. Pretty close for a cheap instrument, at least.
When I checked my own body temperature using the under-the-tongue method, I got 94 F. I think the thermometer is inaccurate in that range, although I know people who might say that it explains my personality. 
When I used it for roasting, the readings for 1st and 2nd crack were very close to those I have been getting with analog (dial) thermometers (a Weber and a Pelouze).
While brewing coffee with a vacuum pot, the temp in the upper part reads 188-190 F., with the water in the bottom part boiling vigorously. This surprised me. I thought the brewing temp would be near 200 F. The coffee tastes great anyway, so no sweat. I use a Nicro Model 500 SS vacuum brewer. I don't have a functioning glass vacuum brewer at this time - I wonder if they brew at a higher or lower temp than the stainless ones.
I've always blamed my lousy espresso on my lousy espresso machine (Gaggia Gran), and now I can do so with justification. It brews at a wimpy 170 F. That's the temp of the water as it comes from the shower head. Knowing that, I am amazed that my shots are as good as they are, that is, acceptable for milk drinks but undrinkable as straight shots. I may be able to do a work-around using the steam switch, but haven't had time to work it out yet.
Too bad it can't be recalibrated, but it's fun to have... and even useful.
Andy
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14) From: David Lewis
At 11:03 PM -0800 11/4/02, Andrew Thomas wrote:
<Snip>
Far be it from me to talk someone out of purchasing a new espresso 
machine, but home units all seem to use one of about three styles of 
thermostat, and they're easy to replace. Home Espresso Repair, at 
, should have ones in stock that are 
higher temperature.
Best,
	David
-- 
"To announce that there must be no criticism of the President, or 
that we are to stand by the President right or wrong, is not only 
unpatriotic and servile, but is morally treasonable to the American 
public."
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