mikepetro wrote:Almost forgot, I think the part number for that probe is HTTC24-K-116U-2.5

I say "think" because I ordered it over the phone and dont have the invoice yet. Its not a stock part but Omega makes custom configurations if you ask them to.

BTW, the back wall of that drum has a high steel content. A magnet sticks to it quite well. I am drilling a hole just big enough to fit a toothpick in a small magnet. When I have all the parts in hand and know precise measurements I will cut a toothpick to simulate the actual length I intend to use and stick it in the magnet. I will then use the magnet to simulate placement and test clearances, with the drum and motor in place, BEFORE I do any drilling.

I went looking for this thermocouple and the correct part number is HTTC36-K-116U-2.5. I am currently using the XCIB-K-1-5-3 thermocouples from Omega with the metal clading. They also have similar theromocouples without the metal clading. Why not buy that style thermocouple instead?

Al

Just curious where everyone is mounting LED2 when fitting the TC4+HTC boards internally to the Hottop?

I just received my parts from Jim and now trying to make a game plan to install everything.

In the black plastic side panel, above and to the right of the Hottop control panel. I drilled a 1/8" dia. hole and pushed the LED partially through from the back and applied a little dab of silicon sealant to hold in place.

Jim

Sounds easy enough. I was over thinking it as always lol. Thanks Jim!

I love that 'little red light' - So good to know when power is getting to the heater even on the rare times I don't plug in the USB

Ron

mikepetro wrote:After trying out my mock probe on every placement I could think of I landed on this: I drew a straight line through the center of the 2 HT sensor screw holes, then drilled my 5/16th hole 10mm above and below those sensor screws. I needed that 10mm clearance for nut on the backside to clear the sensor screw.

How is this working out for you, Mike? Is 10 mm from the screw deep enough into the bean mass to give accurate readings with 227-300 g?

I am finally getting around to installing my controller this weekend. The roaster is disassembled, cleaned, and ready, but I'm still debating the specifics of how to mount my TCs. I'm using the 24 ga (0.51 mm) bare wire Kapton insulated TCs from Omega. I'll probably mount them behind with silicone. They are pretty stiff wire, but does anyone have some advice on how far I should stick them into the roast chamber to avoid the possibility of damage?

Here is the pattern that I created and used which might assist you in locating the holes. It is setup to be placed on the electronics' side of the back wall (print mirror to use on drum side). Be sure to print it at 8.5" x 11" with no margins. If it does not print in the proper size I will place the file on my website later next week. The circles with the squares around them should align with the holes in the backing plate. Shine a bright light on the opposite side to locate the pattern accurately. As always, use at your own risk. Be sure to check for drum clearance before drilling. Drum design has changed over the years!


Above are the thermocouples I made, installed. I used stainless steel 3/16" tubing and Omega pre-made thermocouples "glued" with their high temp bedding compound. I used 20ga for longer life. They are quite tough. I was worried that they would not respond quickly, but they seem to work quite well, registering very fast from just a pinch of my fingers. I tested a roaster with this installation this morning and I like teh BT placement as it does not seem to trap beans between it and the drum.


The back of the thermocouples showing the compression fittings (also from Omega). These allow easy adjustment of the depth of the thermocouples as well as replacement with just simple hand tools. The thermocouple wires are run through high-temp silicone tubing.

Thank you for the diagram, Randy. I'll print it at home and let you know if it's okay.

I like your idea of using metal tubing to protect the insulated wires, leaving the tip exposed. It seems like a good compromise between thermocouple types. I'll see what I can dig up to do a similar installation. Unfortunately, another Omega order is probably not an option because of shipping, so I'll have to see what I can come up with for mounting hardware. Would you mind measuring the insertion depth of your TCs?

I decided to make those as anything close was either cheap imports or too expensive AND too long. The total length of the stainless tub is 2.75" and the amount in the chamber is ABOUT 1cm.

Would two more of the type k thermocouples from Hottop work instead?