I roasted 227g. of El Salvador Las Mercedes Pacamara from Klatch this morning. I expected to roast to a bean mass temp of @ 400 to 425f. The following profile shows the actual roast, but I reached second crack well below that temp. It was my intent to eject right before 2nd crack. I have noticed most of my roasts are fine as far as taste and total roast time, but temps seem lower than the stages I read about. Using a HotTop roaster. Comments?

It is good to see that you have fixed the problem of spikes in readings.

Comparing temperature readings between different roasters with different thermocouples in different locations is not easy and I suggest you concentrate on your readings without worrying about temperatures reported by others. It seems from the chart that your BT thermocouple is reading rather low but this is not a problem as it will be consistent between roasts.

For your case I suggest you modify the default "Action at T1" action table settings to the following:


The remaining action table settings can be left as default. This will turn the heater down to 65% about one minute before first crack starts on your roaster. This will result in the ET curve levelling off much more and at a lower temperature. The time from first crack start to second crack start should then be closer to 3.5 to 4 minutes.

Following the above you should get something nearer to that shown in this chart.

This is in Celsius but the actual temperature readings are not important. You should be aiming for something closer to the shape of this curve at the end of the roast and the time between cracks.

Further information on how to use the action tables and how to fine tune the settings to obtain the roast you desire is given in the RoastLogger manual and this thread especially in my post dated Feb 03, 2013, 7:47 pm.

Once again, thanks, Tom. I will adjust the action table and have another go. I did replace the thermocouples with the type 3 and all works much better.

Dave

Looks better:

That was quick! You are almost there now but you can see that the ET is dropping towards the end of the roast which is not ideal. This is affected by the heater setting applied 60 seconds after first crack starts. I suggest you change the default heater setting in the "Actions at seconds after first crack" action table from 50% to 60% this will stop the ET dropping. This will also shorten the time from FC start to end of the roast slightly.

After that you can make adjustments as described in the link in my previous post to adjust the time between cracks to see what you like best. You may also want to try more or less beans to increase/reduce the overall roast duration.

The settings you last used are always saved and restored between roasting sessions but, once you find settings you are happy with, you may want to save them to a file so that you can always restore them after making other changes.

Could I also suggest that you increase the size of the main window containing the chart before saving it to a .png file for posting on the forum as a larger chart would make it easier to see what is happening.

Thanks so much, Tom. I tried your suggestions with a fan action (75% at 60 sec after 1C, 100% at 120 sec.) This was an Ethopian Sidamo I got from a local roaster. @ 235g. Don't feel you need to keep responding - I'll keep tweaking and tasting.

I'll also work on sizing the graph. Seems a little wonky.

Pacamara can easily carry too much momentum into first crack, more than most other beans. The timing and heat adjustments I'll tend to do a bit earlier.

GreenBean wrote:That was quick! You are almost there now but you can see that the ET is dropping towards the end of the roast which is not ideal. This is affected by the heater setting applied 60 seconds after first crack starts. I suggest you change the default heater setting in the "Actions at seconds after first crack" action table from 50% to 60% this will stop the ET dropping. This will also shorten the time from FC start to end of the roast slightly.

After that you can make adjustments as described in the link in my previous post to adjust the time between cracks to see what you like best. You may also want to try more or less beans to increase/reduce the overall roast duration.

The settings you last used are always saved and restored between roasting sessions but, once you find settings you are happy with, you may want to save them to a file so that you can always restore them after making other changes.

Could I also suggest that you increase the size of the main window containing the chart before saving it to a .png file for posting on the forum as a larger chart would make it easier to see what is happening.

I curious as to why you say its not ideal to have the ET drop at the end of the roast like that? Whats your reasoning?

That looks good to me, Dave. I suggest you use this as a starting point and experiment from there to see what you like best.

One thing that you may wish to experiment with is reducing the high fan settings you are using towards the end of the roast. Personally, I prefer roasts with lower fan settings. I never use more than 40% fan during my roasts. Stretching the end of the roast can be achieved easily with the other action table settings provided by the RoastLogger without the need to use high fan settings i.e. reducing the heater setting at 60 seconds after FC starts from your previous setting of 60% to say 55% will compensate for dropping the fan from 100% to 40%.

dustin360 wrote:...I curious as to why you say its not ideal to have the ET drop at the end of the roast like that? Whats your reasoning?

Dave (Ol'Timer) has recently fitted a HT Roaster Interface (TC4C + HTC) to his Hottop and is using RoastLogger for control and logging. I should have made it clearer that I was addressing my comments to this specific situation.

With this arrangement it is relatively easy to adjust the shape of the curve and the time between cracks by making simple adjustments to settings. I was showing Dave, in just two steps, how to adjust these settings to get the desired curve for his roaster. This is only intended as a starting point from which he can experiment to find what works best for him.

I do not believe that a small drop in ET towards the end of the roast is a big issue but I have found, using this system of control for over three years, that I prefer roasts where the ET is flat to slightly rising to roasts where it drops at the end of the roast.