We focus a lot on improving temperature control and monitoring abilities. What about the effects of bean agitation? Increasing bean agitation can improve evenness, batch size and lessen scorching/tipping issues. I especially like evenness over the surface of each bean. It seems most commercial roasters have more agitation than homeroasters. The reason I believe off the shelf homeroasters don't have more agitation is the trade off of noise. Noise in general and noise that interferes with hearing first and second crack. In a heavy commercial roaster the substantial bean mass with the heaviness of the drum and roaster body still allows you to detect the crack through the tryer hole. In homerosters, stronger bean agitation causes more, higher pitched roaster noise. My roaster uses high speed agitation and at full run rpm's (about 240rpm) I can't hear the cracks well enough. The stirrer is on a rheostat and I can turn way down to hear for a moment when needed. IMO,I don't think that hearing the full crack cycle is a good trade-off for the decreased agitation. As long as BT can be monitored what makes hearing the cracks that valuable? Especially if a momentary check can be done by quickly switching off and on the agitation. I found adding a faster motor on a Behmor improved the capabilities and qualities of the roast but did add a little more noise. I've wondered if the Hot Top with a faster motor would be better. And most homeroaster drum agitation might be improved with more sophisticated veins/fins as is common in commercial roasters. But again, noise level would increase. I've been playing with adding mechanical agitation to a popper that would increase control and batch size.

More agitation, up to a point, also increases convection heat gain and allows for faster roasts or higher loads at the same environmental temperatures.

has anyone modified a hottop for faster rotation? It's high on my list of wanted upgrades, but I don't really know where to find a new motor.

I haven't played with a Hottop. But was able to find a new one for 15.00 on ebay for a friends Behmor that was a pretty simple conversion. There are a number of online surplus vendors too. If someone has a dead Hottop motor to send me I'd research it. Another approach is to examine the action from the fins/veins to see if some improvements that would break up the bean mass could help.

Has anyone followed up on this idea for the Hottop? A replacement motor of a higher RPM controlled by a rheostat to fine-tune things would be great, but my guess is there's a fixed ideal RPM so the rheostat wouldn't be needed long term?

farmroast wrote:What about the effects of bean agitation? Increasing bean agitation can improve evenness, batch size and lessen scorching/tipping issues. I especially like evenness over the surface of each bean. It seems most commercial roasters have more agitation than homeroasters. The reason I believe off the shelf homeroasters don't have more agitation is the trade off of noise. Noise in general and noise that interferes with hearing first and second crack.

HI Ed
As you are aware I have a kit roaster in development that combines manufactured parts and off the shelf parts
Currently the roaster is in Beta testing phase

From my testing of single blade agitators to double blade agitators I found that a simple spring at the bottom was one of my best inventions
This clever spring mod addition on the blade has 3 major benefits
1] Adjustment for height is not as critical
2] Alleviates occasional green beans that jamb under the blade
3] Softens the noise generated while agitating

These are the blades I have been testing


And a picture of the spring placement on the bottom edge


You can judge the video testing of both versions

Double agitator with springs in action look for the indicator beans


Single agitator with spring in action look for the indicator beans


I am very satisfied with the double paddle design

KK

I like those! I've been watching the progression of the design, the marked beans are moving around well. Like your lid to pot adapter ring a lot.
My bean bats are only 2.25mm round rods. But mine have a different job as they work to elevate the beans at a high rpm. They simply bat the beans. The beans are spread out around the side-walls. The beans don't really touch the bottom much. The convection from the top works down the sides due to the fan design directly into the bean mass and then returns up the middle. I avoid a high MET of convection with the variac.

farmroast wrote:I like those! I've been watching the progression of the design, the marked beans are moving around well.

The motor is rated to operate at 68 RPM @ 2 kg per sq centimetre and manufactured to my specifications from an automatic door motor
The double paddle effectively doubles the RPM

farmroast wrote:Like your lid to pot adapter ring a lot.

Thanks Ed
I have had many emails from the US,Canada,NZ & EU regarding supply of all the manufactured component parts
They are all now available for the DIY person
Amazingly the base hub and the adaptor ring can produce about 20 different designs of home coffee roaster

All the best Ed
KK

The double paddle design looks like it provides great(even) agitation. Where can I read/see more about this roaster of yours?

JmanEspresso wrote:The double paddle design looks like it provides great(even) agitation. Where can I read/see more about this roaster of yours?

I like sharing my ideas
If you want to build one yourself of the original design go here
http://docs.google.com/present/embed?si..._0c97xkwgg

If you want to read about its progress go here
http://www.homeroasters.org/php/forum/v...rowstart=0

If you want to read about the kit in beta testing go here
http://coffeesnobs.com.au/YaBB.pl?num=1261484678/0

KK