Installing ET and BT probes in a Hottop - Page 7

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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JohnB.
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#61: Post by JohnB. »

Louis wrote:and the wires come out from the bottom of the back panel... in which I cut a small rectangular hole to accommodate the two wires. The Hottop feet seem high enough to prevent the wire from doing a sharp 90° bend. I think it should be fine.
Same thing I did 16 months ago & no problems yet so I'm sure they'll hold up just fine.
LMWDP 267

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mcwresearch

#62: Post by mcwresearch »

I just completed an installation of two probes using the same method as JohnB, Mark (Mutts), Louis, et al. Thanks to everyone for sharing their methods and ideas!

The only difference is I used probes with stripped leads (XCIB-K-1-5-3) and terminated them in mini panel jacks I mounted in the back of the roaster, much like ElBean did. I installed four of the panel jacks; two are currently used to measure BT and ET and two for future use. Connecting them to the data logger are two retractable sensor cables (RSCM-K-1-4-4).

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I didn't use any fittings and instead just used an 11/64" cobalt drill bit to get the hole just big enough to fit the probe through and then secured it with JB Weld high temp epoxy.

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I extended the probes 1 inch into the drum and had to bend the BT probe in order to dodge the fin, just as Louis mentioned doing.

It's nice not to have to monkey with the long probe sticking out of the chute cover and I finally have an accurate ET reading.

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cannonfodder
Team HB

#63: Post by cannonfodder »

Nice hookup. I was lazy and just ran the TC wire out the back though the seam between the base and body. I just put a small notch on the flange so it would not pinch the wire.
Dave Stephens

mike01

#64: Post by mike01 »

Thanks everybody for posting your ideas for installing temperature measurement. There is some great info here. Anyways, I recently installed BT and ET thermocouples in my Hottop in a similar method to the other installations here. I was just wondering what temps other people were seeing for 1st and 2nd crack. My temps seem a bit lower than I expected. I just did my first roasts today and I'm getting 1st around 375F and 2nd around 415F. Does that seem normal? Thanks.

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JohnB.
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#65: Post by JohnB. »

I normally see 1C take off between 380*F-395*F/BT depending on the bean. 2C is typically 40*F/BT higher but you never know with some DP beans.
LMWDP 267

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Italyhound

#66: Post by Italyhound »

I am trying to learn how to take apart the machine so that I dont have trouble with disassembly when I am ready to install my probes.

I ran into quick trouble removing the fan using these instructions on the HT site: http://hottopusa.com/fan2.html

I don't want to force anything but getting that connector apart is not happening. I took a picture of the connector and there are prongs on the fan half of the connector that are prevented from separating by butting up to the half connected to the machine. It says wiggle and pull but I am afraid I am going to break it - it wont budge.

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Any help appreciated.
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JohnB.
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#67: Post by JohnB. »

It should just pull apart. Keep wiggling the two halves but don't pull on the wires..
LMWDP 267

germantown rob

#68: Post by germantown rob »

Make sure there is no compression locks to press, the older one I have definitely did not have this.

Sometimes grip is the problem especially on connectors that have not been apart and together a few times. In times like this I use a pair of pliers to grip one side or even pliers on both sides to aid in grip, just enough pressure to give grip and not compress the connectors.

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Italyhound

#69: Post by Italyhound »

Thanks. Needed needle noses but it went. hopefully it is loosened for next time.
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Italyhound

#70: Post by Italyhound »

I can't thank everyone enough for the help. I finally got my probes installed and really appreciate the web page that mcwresearch set up to guide one through the process. I am nowhere near handy but with a fair amount of help it got done without any trouble. Now to begin anew - relying on actual temps! It's like starting all over again :D

I took pictures and it's almost exactly like mcwresearch's set up (I used 2 panel jacks not 4)... but .... for some reason the pictures are uploading to the site sideways even though they are rightside up on my mac. :?:

I also want to add some basic tips I got from several people about this modification since when I read through the thread it was populated by people who seem very comfortable with such mechanical alchemy. I am not that person and got it done. You need some screwdrivers (small flathead, philips and a slotted flathead that has a long shaft to get the ejection lever out), a drill with variable speed and 2 drill bits.

I followed mcwresearch's helpful web page http://www.fourpointsroastery.com/insta ... p-roaster/ for this. Many thanks.

- You need to take the almost completely machine apart (fan, rear cover, top cover, temp sensor and move the motor aside) to expose the back for drilling. When you do, take the opportunity to clean what you can. I used Caffiza which works really well. I kept track of the many different screws by placing them in little ziploc bags labelled for easy reassembly. "motor screws" "rear cover" "fan" etc. The instructions with photos on the hottop site on how to disassemble the unit are terrific. I assume thanking Randy for that is in order. I did not take the motor out completely so I did not disconnect the control board. I set the motor on a little box so it wouldnt fall and damage the wiring so be careful if you leave it on. I think taking it off wouldnt be hard but less is more for me.

- The only required work is drilling through the rear wall. If you are not handy and have a friend who is, let them help you. Otherwise, I will tell you the tip I learned about drilling through steel. An 11/64 hole will fit the thermocouples used widely in this thread. You want to start with a small pilot (starter) hole and use a bit for steel. I used cobalt as recommended by others. I used a 3/32 or 5/32 for a pilot hole - cant recall right now. For steel, oil your bit and keep it oiled. Dont push hard like you would for another surface perhaps. Be patient and keep the speed relatively slow. I may have gone too slow but it got done eventually. The drill bit will want to 'walk' on the steel so I was correctly told to keep the drill speed lower and not push. I stopped, oiled and started again. When the pilot hole is drilled, switch to the larger bit and the second hole will go more easily. Once done, I took a metal file and scraped away any sharp bits that hung around the hole. Here is a video I had looked at showing a guy drill much thicker steel than you will face.
- I used heat rated JB weld epoxy to secure the thermocouples but not everyone does. It is readily available near me and really easy to use.

- I chose to install the panel jacks in the back cover but you don't need to. It's a little cleaner looking. The rear cover plastic is soft and thin. I was able to use a friend's jigsaw (first time ever) but honestly with patience and an exacto knife, I am confident you could scrape a cutout with no trouble. Will take u a little while.

Again - I am no expert but got it done. Hopefully this helps another person with barely apposable thumbs - like myself - in the future.

Evan
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