Hello all,

First time user here. Nice to meet you all

I've been browsing and reading the forum after searching for some info on turning a bread maker into a home coffee roaster (as I am interested in doing the same). I came across a few projects but with all of them I noticed that a heat gun is used as the source generating heat.

I was wondering if there is any specific reason for not using the original heating element that came with bread maker? Baking bread is usually done at 350F or 180c, this is not high enough for roasting but surely it could be stretched further to reach those temps ... ?

Thanks!

My previous roaster was a HG/BM. There's a good reason why you shouldn't use the built-in heating element. First, it doesn't have enough power, you don't want to bake beans, you want to roast them, which requires significantly more power than the heating element within most bread machines I've seen has (even if it can get to the temperature, you need to get there FAST, and controllable). Second, you don't want to use it to "boost" the heat, as it would just be too uncontrollable.

A good heat gun with an adjustable airflow and adjustable temperature is the best. It will cost around $75-$150 from what I remember, but it's well worth it. After that you should get a temperature probe (like a candy thermometer etc) that you can drill through the outside of the machine into the bread-pan. This will give you a good bean temp, just make sure the direction of stirring beans won't push the thermometer out as it goes.

One last thing is either you can keep the top open with a fan blowing across to make sure you're getting fresh air into the heat gun, or you can take out the window in the lid of the bread machine and put some tin foil around the opening to put the heat gun directly in. Either way works, but I prefer the second method.

After these mods, you'll have a very nice roaster that can roast with the best of them (at least in my opinion).

I used a BB with a CO top. I wired a circuit with a variable on/off interval to adjust the heat of the BB element for a little added heat. The BB also served the function of agitating the beans. The main heat came from the convection oven, basically a more powerful element with a fan. I think the ideal would be to also gain control of the CO heat and fan settings. A powerful heat gun might be better than a convection oven out of the box because easier to control the heat.

Thanks for the replies.

I would prefer not to go down the path of using a heat gun, not because of the cost but mostly because I find it more cumbersome. Also I would like to have the unit controlled by a microchip, and the heat gun would harder to "plug-in" to.

Is it required to have the beans in the roasting chamber from the start? Assuming I use a standard bread maker heating element [which will require longer to heat up], is it acceptable to drop the beans only when the temperature is right?

As explained earlier , the breadmakers element will not roast the beans ,the breadmaker is used to agitate the beans, you will need to use a heat gun.

slepax wrote:I would prefer not to go down the path of using a heat gun, not because of the cost but mostly because I find it more cumbersome. Also I would like to have the unit controlled by a microchip, and the heat gun would harder to "plug-in" to.

Is it required to have the beans in the roasting chamber from the start? Assuming I use a standard bread maker heating element [which will require longer to heat up], is it acceptable to drop the beans only when the temperature is right?

As others have written, the heating element will not provide enough heat for roasting coffee. The logic of a HG/BM is to use the bread machine for agitating the beans so they heat evenly and the heat gun for heat and airflow. You would think it is a crude and cumbersome device. Actually the HG/BM is a very responsive roaster. If you want to roast coffee that tastes good you will need the ability to adjust temperature and airflow on the fly and a heat gun is very effective for this. With my HG/BM I start with the coffee in an unheated bread pan. I turn on the agitation and the heat gun and this starts the drying phase, which proceeds without problems.

So, part of understanding why we are recommending the heat gun is understanding the roast process. There are times when you will want to push it with a lot of heat, other times when you will want air flow with little heat to decelerate temperature increase. The weak bread machine heating element outside the pan just won't give you enough power or responsiveness.

If you want to try it, go ahead. But you're asking something akin to how to best chew coffee beans to grind them for espresso.

slepax wrote:Thanks for the replies.

I would prefer not to go down the path of using a heat gun, not because of the cost but mostly because I find it more cumbersome. Also I would like to have the unit controlled by a microchip, and the heat gun would harder to "plug-in" to.

Is it required to have the beans in the roasting chamber from the start? Assuming I use a standard bread maker heating element [which will require longer to heat up], is it acceptable to drop the beans only when the temperature is right?

If you're dead set on it, go for it. But based on bread machines I've seen...it's just not going to happen. Maybe you have something different? The basic idea is that even if you pre-heat your bread machine to a similar drop temp of other roasters, it will lose that heat fast to the beans and have no way to recover in a somewhat normal time. You need a practical heat source that's controllable. You could go with a gas burner, or with electric, or maybe IR heaters, but those are the main ones because they offer the amount of heat (BTU output, not just temperature capable) that can roast a reasonable batch size (100g+).

If you consider a heat gun too cumbersome to use...I may suggest that you go with a Hottop or Behmor roaster. A heat gun (which is the real roaster here) combined with a bread machine (this originally was a stainless dog food bowl + wooden spoon) is a very manual roaster, but that's exactly what some people are looking for. If you'd like a press-a-button roaster, I'd suggest you stop looking at HG/BM and start looking at those.

Once again, thank you all for your replies.

I'm not dead set on it, and surely you guys know better so I will take your word and trust your experience. Sorry if I sound stubborn, I'm not, I just like to understand the fine details and reasons behind everything. I understand now the requirement and the variability in heating requirements.

I am not completely against the heat gun solution, but I would like to automate the process as much as possible, and with that also have a solution that is one box and requires no assembling. I don't see this as a press-a-button solution even if I desire the assembly to be one single unit. And automation doesn't necessarily mean less control, I just think it will give me better monitoring and insight (plus it would be a nice project).

Since the heating element is off the table, I will have to think of some other creative ideas (a microchip controlled heat gun + BM maybe )

Generally the way you can vary heat with the HG/BM method is 2 ways. First if your HG has no variability (or very little with high/low), most people opt to roast with the top open and vary the height of how close the HG tip is to the bean mass. Second way is buying a variable heat HG that has a digital temp with up/down, or sometimes has 5-10 different heat levels. This usually allows you to close up the top of the BM and roast with a bit more control and a bit more like a traditional drum roaster.

Alternatively with the Behmor, from my understanding they have a couple built in profiles that you can pick from. The Hottop is a bit more premium and allows both pre-set profiles, programmable profiles and manual control. It can also be modded with more electronics later on, the TC4 board is pretty popular because it can be used to PID the roaster. I use the TC4 board with a Quest M3 and manually adjust fan/heat based on what I'm seeing on my laptop.

There's a lot of other roasters out there, mostly it depends on what you want to do and your budget. But if you're thinking of automating the roasting process, forget using a HG + BM. At least that's my opinion. It may be somewhat possible with a variac + PID electronics, but I'm really not sure how well it will turn out. Again you would still have to be controlling the HG using your electronics, but I believe it would be possible. Still I'd recommend for what you want to do to look into a Hottop with the possibility of modding it in the future.

With my HG/BM I'm satisfied that the control is manual/analog and the tracking of roast profile is digital. My HG has Hi/Low settings and a fan dial for each. It's very responsive and was bought from Harbor Freight for something like $75. At the end of the roast I lift that off and have to use hot gloves for a stove to quickly lift out the bread tray and dump it onto a cooling grate with a fan underneath. This is not as nearly smooth a process as roasting with my drum roaster, but I can do small loads and the roast quality is very good. I prefer my HG/BM to the Hottop I once had but sold.