DISCLAIMER: DOING THIS MAKES THE HOTTOP A FIRE WAITING TO HAPPEN IF YOU LEAVE IT UNATTENDED DURING A ROAST!!!! DON"T TRY THIS IF YOU HAVE A PROPENSITY FOR WALKING AWAY FROM YOUR ROASTS!! I CANNOT BE HELD ACCOUNTABLE FOR ANY DAMAGES RESULTING FROM THIS MODIFICATION. I DON"T RECOMMEND DISABLING SAFETY FEATURES---THIS IS FOR EDUCATIONAL PURPOSES ONLY. PROCEED AT YOUR OWN RISK!!

I think i've found a pretty simple way to trick the hottop out of some of the annoying safety features---namely the timer starting after preheating to 166F (instead of when you want to start the roast/countdown), the max roast temp of 428F, and the mandatory cool down post roast. all that's needed is to unscrew the HT temp sensor and re-route it to be outside of the hottop. This way the hottop always thinks its cold, so preheating will go until you subject the sensor to 166F (by touching it to the side of the hot, and nicely preheated body, or just under the bean loading chute). This will give you 25 mins of roast time, starting at your ideal charge temp, which is more than enough time for a roast. IF YOU LEAVE THE ROASTER UNATTENDED AFTER STARTING THE ROAST, IT WILL HEAT UNCHECKED UNTIL IT CATCHES ON FIRE (OR THE THERMAL FUSE TRIPS).

Once the countdown timer has been triggered to start, the temp sensor can just sit by while the roast goes on, since it doesn't seem to care if the temp drops to room temp during a roast. Also, its virtually impossible to hit the max temp. Eject the roast as you normally would. Since the temp sensor thinks its cold, you can start the next roast immediately if you want (i would recommend waiting at least a few minutes, as i'm sure the plastic components won't last long, under long term roast temps). Use common sense, and remember that the hottop isn't made to run at temp all day long, but this is convenient for doing a few roasts back to back when you need a pound.

Obviously you need external temp sensors to tell you what's going on, since the temp display will be useless during a roast. I have tested this mod, but have not implemented it full time, as i'm still waiting to get my TCs set up (the other benefit of this mod is the hole where the original temp sensor was, can be re-covered with a small piece of metal that you can drill through to put your own temp probes through, without damaging the hottop.

Good luck and be safe.

Love the idea! Simple, clean and, I assume, reversible.

Now, a few things:

- The HT controls will result in different behaviors at different HT heat states. That is, your heat transfer from P=10&F=4 on a starting from cold and pre-heated HT will differ from your heat transfer from P=10&F=4 on a HT that just got down to temp after a roast.

- Why not install a switch that switches between the original sensor and one that's dangling outside the roaster? That way you'd switch to the one outside only when you need to override the original behavior. I have no clue how to do this, BTW.

It's a great mod idea (especially with a switch) but I can't see how it would be useful if one is serious about profiling since it changes the heat dynamic. If you want to roast two/three batches back2back with this mod, while using the same exact profile, things would be tricky because you want your HT to be in the same heat state for the roasts to be consistent. A solution is to develop a multi-roast profile where you learn how your HT acts on the 1st roast, 2nd, 3rd . A second, possible, solution is pre-heat your HT for a very long time till you get to some state of heat equilibrium then start profiling from there...I just don't know if the HT can take this or if an equilibrium is even possible.

Regardless of usefulness, I just love a simple mod

i like the switch idea even better, though in that case you'd have to buy another sensor. maybe just switching the sensor on/off at key points would work? i'm not enough of an electrician to know HT would handle that with the existing circuitry (which is always why the mod is so low tech )

i have also noticed the different behavior in temp with back to back roasts, but so long as the starting point is the same temp, and the bean mass is the same, you can get pretty close to the same profile you started with in a cold HT.

if the roast was always started at an ET of 300F for example, it seems like the profile for a given set of HT parameters and given bean can be predictable. it would just take a bunch of trials to see how the behavior changes roast to roast.

The first roast (unless you did a pre-heat for a full or nearly a full cycle) will be different. For back-to-back roasts with a pre-heated roaster, with the same starting parameters, the hottop runs dead on (or as close as a manually controlled roaster will run). I've done 10-20 back-to-back roasts with the same origin (country, not estate), and had roast results (drying, 1st crack, end of roast, mass loss) practically the same. Did 20 roasts of 230g start mass, using the same profile, with end mass within 2-3g across all the roasts, using a scale that measured to the nearest gram.

The hottop is a very consistent roaster, in my experience.

cfsheridan wrote:The first roast (unless you did a pre-heat for a full or nearly a full cycle) will be different. For back-to-back roasts with a pre-heated roaster, with the same starting parameters, the hottop runs dead on (or as close as a manually controlled roaster will run). I've done 10-20 back-to-back roasts with the same origin (country, not estate), and had roast results (drying, 1st crack, end of roast, mass loss) practically the same. Did 20 roasts of 230g start mass, using the same profile, with end mass within 2-3g across all the roasts, using a scale that measured to the nearest gram.

The hottop is a very consistent roaster, in my experience.

I would not overestimate the significance of getting the same final roasted bean weight after repeated roasts. I always use 454g charge weights in my 1lb sample roaster (that a long time ago I used to roast 500g batches in, but that is ancient history at this point), and I weigh each batch after roasting on an accurate electronic gram scale. In spite of what can be fairly obvious differences in profile among batches, as long as I go to the same final temperature my batch weights are nearly always within a gram of each other, for a given coffee roasted to the same final temperature. I do try very hard to roast consistently, however my roaster is 100% manually controlled and as the roasting session drags on the drum stores more and more heat, plus, the ambient temperature in my garage can change, especially in the winter. I tend to roast at least 2lbs of a given coffee each roasting session, and often as many as 5, all of which get blended together (for a given varietal), which cuts down on the variability from roasting session to roasting session.

Each coffee is different and seemingly similar coffees often will have different end weights, when roasted to the same final temperature with an essentially identical profile. It is usual, however, for a given coffee to have all its final roast batches weigh within a gram of each other, and this is starting with about 2x as much coffee as you are starting with, e.g. 454g.

I'm not saying you shouldn't weigh your coffee; you should. It provides an important data point, and for free. I would not, however, over-interpret nearly identical batch to batch final weights as indicating total consistency on the part of the roaster. I do not think that this is the case.

ken

coffee.me wrote:I just don't know if the HT can take this or if an equilibrium is even possible.

cfsheridan wrote:I've done 10-20 back-to-back roasts
. . . .
Did 20 roasts of 230g

Thank you Chad for the hands-on report! I'm interested in hearing your thoughts on reliability. Have you been doing this for a long time? What's your mains voltage? Any issues with the heating element, motor or plastic parts? Is the HT taking it well?

Oh, and how do you clean between batches?

The final gram weight was an example of consistency, not the full story, certainly. Roast colors, profile times, and finish times and temperatures were all consistent. Looking at the logged profiles, the temperature curves were consistent as well. Were they exact. No, but I would argue that the hottop is capable of sustained consistent roasting.

I have two dedicated 20A circuits in my roasting space, so voltage generally is steady. I do see differences in daytime vs. nighttime during the summer.

As for cleaning, I blow out the drum with compressed air after every roast, and remove the drum and wipe down the inside of the roaster about every 25-30 roasts. I remove the rear of the roaster and clean out everything every 50 roasts or so.

cfsheridan wrote:I've done 10-20 back-to-back roasts...

did you do these roasts with the HT's required cooldown between roasts? if so then its not surprising that the HT can stand up to the abuse.

Yes--I've not rigged the machine to eliminate that "feature"

Figure 5 minute cool down time for the beans (they're usually cool at 3:45 after dumping), then another 4-5 minutes to cool down and heat back up to my start temperature. Better for the electronics, perhaps, but that imposes more duty cycles on the metal parts. I'd say it's a toss up between whether more time at temperature or more thermal cycles for the machine (at least the metal and mechanical parts.)