Behmor

[Dragunov21]

Not likely... think about what you're trying to achieve.

IR pointed at the bottom of the drum would be the only thing I can think of.

[fruity]

Anyone had any success getting a temp probe into the bean mass inside the behmor drum?

It would be challenging. I figure you'd have to go in through a modified pin on the left edge of the drum (drilled through the pin) and then drop it straight down into the bean mass, somehow clearing the vanes.

If you had the right tools you might be able to do it.

[thegoner]

How do behmor owners plot the roast (temperature wise)?

[fg1972]

Not likely... think about what you're trying to achieve.

IR pointed at the bottom of the drum would be the only thing I can think of.

I am trying to achieve more accurate, meaningful temp monitoring as opposed to me currently just reading the air temp inside the behmor which is helpful but not quite the same as reading the bean temp.
For example; from the air temp reading, 1C may start at 270 degrees one day, then 290 on another day. I bet the bean temp doesn't vary that much.
If opening the door to try extending 1C - 2C, air temp shows a drop but what is bean temp doing? This is the temp that I ideally want.
When I was using a popper with a TC reading the bean temp, 1C would pretty much always occur at 195-200 degrees regardless of air temp.

It would be challenging. I figure you'd have to go in through a modified pin on the left edge of the drum (drilled through the pin) and then drop it straight down into the bean mass, somehow clearing the vanes.

If you had the right tools you might be able to do it.

This is the method I've been going over in my head for weeks and agree with you that it would be challenging but thought I'd put the question out there hoping that someone had a better idea.

How do behmor owners plot the roast (temperature wise)?

I have a probe reading the air temp just above the drum and another probe under the chaff tray.
Initially I would manually plot the temps each minute on the HGBM spreadsheet provided by one of the coffeesnob members.
Then I started using RoasterThing software to plot the temps, still a manual process.
I now have a temperature logging board for RoasterThing which automatically plots the temperature.
Lots of others are successfully doing it with Andy's USB data logger available from Beanbay.

[Dragunov21]

I am trying to achieve more accurate, meaningful temp monitoring as opposed to me currently just reading the air temp inside the behmor which is helpful but not quite the same as reading the bean temp.
For example; from the air temp reading, 1C may start at 270 degrees one day, then 290 on another day. I bet the bean temp doesn't vary that much.
If opening the door to try extending 1C - 2C, air temp shows a drop but what is bean temp doing? This is the temp that I ideally want.
When I was using a popper with a TC reading the bean temp, 1C would pretty much always occur at 195-200 degrees regardless of air temp.

I totally understand what you're trying to do an why; FWIW if you could get an IR setup, that WOULD read the surface temp, not the air temp.

Unfortunately, fruity's suggestion is all you've got, because you have a closed, rotating cage, so your only points to penetrate would be where the axis of rotating hits the cage (ie the left and right shafts.

The right shaft is out because it's (presumably) directly attached to the motor shaft.

The left would be possible if modified but you'd need a rigid wire to mount the TC probe to so it wouldn't move in and out of the bean mass. IIRC the vanes overlap slightly, so you'd have to have the wire free to rotate and clear the vanes before falling back into the mass, I think.

I really think it would be more effective to point an IR thermometer at the base of the drum, perhaps pointed through a port drilled in the lower LHS of the machine?

[fruity]

Anyone looked into an RFID temp sensor? You could chuck it in with the beans then, and monitor the bean mass temp directly.

I googled for a bit but couldn't find one rated for 200+ degrees, nor any pricing, but maybe it's an option?

[thegoner]

It would need to be able to emulate physical mass of the green bean as it heats up and cools, then change to emulate the roasted ones as it happens. That is going to be tricky.

Do commercial roasters have this dilemma?

[Dragunov21]

Not to mention it would need to emulate the exothermic reaction that apparently occurs part-way through the roast (which aint gonna happen). Great idea though.

Honestly I don't know why (unless you were trying to produce roast profiles that could be transferred to other roasters/etc) there's a need to focus on the internal bean temperature.

As long as your roaster, bean type/weight and measurement method stays constant, all you need is a reference so that your measurements are indicative of the bean temp to allow you to tailor your profiles and maintain consistency of roasts.

Admittedly you won't be able to say objectively "I held my beans at x° for ysec" but the measurements should be indicative enough that you can intentionally adjust your profile until it tastes great, then repeat it as desired.

Or am I missign something?

[fruity]

It would need to be able to emulate physical mass of the green bean as it heats up and cools, then change to emulate the roasted ones as it happens. That is going to be tricky.

Do commercial roasters have this dilemma?

Why? Why couldn't it just measure the temp of the surrounding beans, just like a temp probe inserted into the bean mass?

[Barry O'Speedwagon]

Anyone looked into an RFID temp sensor? You could chuck it in with the beans then, and monitor the bean mass temp directly.

I googled for a bit but couldn't find one rated for 200+ degrees, nor any pricing, but maybe it's an option?

If you ever find one Fruity, please start a thread with the news. Would be very handy for use in a Gene Cafe as well (as long it's not too small). I guess I'm not surprised that there isn't a huge international demand for an RFID temp sensor rated to 250C.

[fg1972]

I totally understand what you're trying to do an why; FWIW if you could get an IR setup, that WOULD read the surface temp, not the air temp.

Unfortunately, fruity's suggestion is all you've got, because you have a closed, rotating cage, so your only points to penetrate would be where the axis of rotating hits the cage (ie the left and right shafts.

The right shaft is out because it's (presumably) directly attached to the motor shaft.

The left would be possible if modified but you'd need a rigid wire to mount the TC probe to so it wouldn't move in and out of the bean mass. IIRC the vanes overlap slightly, so you'd have to have the wire free to rotate and clear the vanes before falling back into the mass, I think.

I really think it would be more effective to point an IR thermometer at the base of the drum, perhaps pointed through a port drilled in the lower LHS of the machine?

Your'e correct about the RHS being not doable as the drum is driven from that side + all the electronics is on the right side of the machine.
IR could be an option, and there is plenty of room on the LHS, I'll have to read into it a bit and see what I can come up with.

[fg1972]

After some Internet research, I've come across a few different IR probes with K thermocouple output (I didn't know they existed) but they are all fairly expensive for what im trying to achieve. If anyone knows of a basic and cheap probe, please advise.

[fruity]

After some Internet research, I've come across a few different IR probes with K thermocouple output (I didn't know they existed) but they are all fairly expensive for what im trying to achieve. If anyone knows of a basic and cheap probe, please advise.

Yeah, I had a look too but didn't find anything below $100 that seemed fit for purpose.

[jbrewster]

After some Internet research, I've come across a few different IR probes with K thermocouple output (I didn't know they existed) but they are all fairly expensive for what im trying to achieve. If anyone knows of a basic and cheap probe, please advise.

Interfacing to an IR temperature sensor with a microcontroller isn't a particularly difficult task, you could just scavenge a sensor from a $30 IR temperature gun and use that, lensing will be a bit of a challenge though, the cheap guns use plastic lenses which will melt at Behmor temperatures, depending on the characteristic of the sensor you might be able to get away without using a lens though (Germanium lenses are the "right" way to do this but that is a significant part of the cost of one of the sensors fruity refers to, Germanium optics are some of the most expensive).

Look up Ben Krasnow on YouTube, ISTR he's done some experimenting with these types of sensors.

[MrJack]

Slightly crazy, but what about a battery powered ardiuno mounted on the end of the drum (shielded from the heat obviously), with a bluetooth or wifi module? The whole thing could rotate with the drum, and you could put the thermocouple(s) anywhere you like. I wonder if you could even have some kind of brush arrangement to provide power (3-5V)?

Disclaimer: I do not know enough about electronics to actually do this