Well, I've done the 113g load. But let's look at this load question only mechanically. . . .and no, my roaster's element is fine, not deformed.

Please remember that there are online reports of people doing loads that go up to 400g, with many talking about the 250-300g range, and they're all happy. I've done 300g & 225g myself earlier, when I was looking at good taste but not much else. With 150g, but more importantly with more experience, I was able to get better roasts. But all that doesn't matter here, so, let's - for this part of the discovery exercise - discuss only the mechanics. Again:

- Element is on the left side of the roaster, taking the space between ~8 O'clock & ~10 O'clock.
- With 300g, I'd estimate that beans got as close as 3cm to the element, IIRC.
- With 225g, I'd estimate that beans got as close as 5cm to the element, again IIRC.
- Now, with 113g, beans never passed the 6:30 O'clock mark, so I'm estimating 9-10cm away from element.

Again, everytime you get closer to the element, the higher the MET; and because we can't measure MET, we give this statement a lot of importance.

The other part is extended pre-heat. The idea here is simple too, give the roaster time to stabilize as to not have too much of a heat differential between different parts of the roaster and, then, need to compensate by using high heat. I have not got to this yet, but it sure sounds good till I get a chance to verify it.

Now, back to the 113g batch:
- same bean & pre-heat strategy as other batches.
- beans never passed the 6:30 O'clock mark in the drum.
- beans didn't cover the HT builtin probe or enough of my BT probe(but I'm inclined to trust my BT reading).
- never gone beyond P=6.
- no burnt smell, could be my nose or amount of beans, have to verify thru taste.

I haven't given the 225g batch or this 113g batch the siphon treatment yet; will hopefully do and report back.

Next batch will be 113g with the same Brazil again, but with a lower charge temp; after an extended pre-heat, of course .

A suggestion--if you can spare the time, it would make sense to do some of these roasts back to back, so that you've got a set of samples for comparative cupping. Sure, the siphon treatment is a method for comparing the cups, but you're left with memories of the previous cup vs. immediate sensations.

You needed worry about cupping technique--just 2-4 roast profiles together and cup to find differences, improvements, defects, etc. Doing this back to back before your next tweak will allow you to enter into the next stage with knowledge of what worked in the cup.

As for the MET discussion--I hear you on the bean mass size and proximity to the heater. That said, I am not sure that 225g vs. 115g (or 150g) and location to the element has THAT great an effect. When I get caught up on this last batch of samples, I'll try to run a few profiles with a high grown bean varying charge mass and charge temperatures.

I'm fairly confident that 225-230g works for my machine and profiles having comparatively cupped a Brazil vs. a beans roasted on a profile we worked out on a profiling 2kg Ambex. That said, I like your work with smaller charges, as I think 230g without some boost on the voltage is at the limits of the machine's power to drive the roast. Been working on ideal voltage vs. charge size, and may end up ~200g at the end. Don't think the machine needs as radical a drop as you have been suggesting, but I do think your work has opened the door on the thought of what is the ideal range of charge mass profiles for the hottop.

cfs

A quick note: if my test bean was a Kenya, a Yemen or any other high grown, I'll simply be wasting my time as high growns won't be as sensitive to MET.

Please keep that in mind, because the plan is to replace this test bean with harder and softer beans; once all the knobs are dialed in -- if that ever happens.

And, Chad, you're right, all roasts on the same table would've been perfect; I can't do it, wish someone else could.

coffee.me wrote:Element is on the left side of the roaster, taking the space between ~8 O'clock & ~10 O'clock.

Forgive my ignorance, but is the element inside or outside the drum on the Hottop?

coffee.me wrote:- With 300g, I'd estimate that beans got as close as 3cm to the element, IIRC.
- With 225g, I'd estimate that beans got as close as 5cm to the element, again IIRC.
- Now, with 113g, beans never passed the 6:30 O'clock mark, so I'm estimating 9-10cm away from element.

OK, now I have better estimates for distance from bean mass to lower edge of element:
- 300g: ~3cm
- 225g: ~4.5cm
- 113g: ~6cm

I also removed the drum, and with an open front, set P=6 till element stabilized then I measured temp differences at 2 distances(i.e. difference from ~6cm = 113g = 0F):
- 300g = ~3cm: ~+50F
- 225g = ~4.5cm: ~+25


@ P>6, I'd guess temp difference would be much bigger and would conclude that beans that can't take the heat would easily char at loads > 150 or so when P > 6 & voltage ~130v.

Before lowering my stabilized, and extended, PH temp, I cupped the 3 roasts we have so far. All roasted to the same degree by color, by TC reading and distance from C2. The 113g had the strongest aromas, the 300g had the most ashyness while the 113g had none and the 225g had some. 225g had the most balance while the 300g had the most body and the 113g had the most brightness. If I didn't roast them myself, I'd guess that the 300g was done on a drum but the 113g was done on an air roaster.

I also Aeropressed them, as the AP tends to remove all but the most visible traits. All were good; but that says more about the AP. However, I can see how people would do any load size and still like it: the 300g was the most "coffee" like, the 225g was the most fruity & avg, and the 113g was the most sweet.

Again, this isn't about profiling or good tasting roasts, it's about understanding the Hottop. So, I did more roasting.
- 113g, same bean but lower charge temp; same extended PH strategy as other batches.
- never gone beyond P=6; just like with the last 113g.

I compared this 113g-lower-charge-temp (113gLCT) to the other 113g. When at the same table, this 113gLCT had no ashyness while the original 113g slightly did. 113gLCT was also sweeter; but it could be the lack of relative ashyness.

Now I wonder what would happen if I never exceed P=4? Knowing my HT, I'd probably have to go with a ~57g load; a ridiculous home roasting batch size but I'm very interested to see what would come out of that! Once done with the tiny load, I have other things on my mind: which batch size gets the most convection heated? I can't make the 300g taste like the 113g, but is the other way around possible? would hard beans gain the same benefits as this Brazil did?

The plan for next roast is to go with 57g, lower charge temp via extended-PH and never exceed P=4. My BT probe won't register correct temps at this load but we'll see.

gyro wrote:Forgive my ignorance, but is the element inside or outside the drum on the Hottop?

Between the drum & outer shells.

Really missing your complete and colorful graphs lately, Max. I know they are extra work! On the last series there, do you have the times to first crack and total roast times for each to compare? Always appreciate everything you share here. Thanks.

coffee.me wrote:gyro wrote:
Forgive my ignorance, but is the element inside or outside the drum on the Hottop?

Between the drum & outer shells.

Do you think it really matters then if the beans are 3cm vs 6cm away from the element if it is separated by a metal drum that is going to be coming towards them (with the heat imparted by the element) anyway at circa 60Hz?

I would understand the concern if the element was inside the drum, but its not. Many big boy roasters from my understanding have the gas heat source at the bottom of the drum, where you can be certain there will beans, and it doesn't seem to worry them.

Cheers, Chris

wouldn't acceleration (rather than linear speed) play more of a role? The goal is to get the beans agitated - i.e. drop them through the center of the drum. Too little centripetal acceleration, and they sit in a mass at the bottom of the drum (except for the vanes). Too much, and they stick to the sides, all the way around. Just the right amount, and you get some nice tumbling.