Do you mean to take the exhaust part out? That is easy after the reducer and I'll try it. I think I saw at HomeDepot a metal duct with a butterfly door inside that controls the air flow. That would make for an interesting adjustable exhaust. Controlling the back pressure does not have the same effect as controlling the fan speed. Low fan speeds don't get rid of moisture condensation and the roaster does not heat up as well (it is fast but with worse results).

What speeds cooling the drum after roasting is opening the little top door (beans feed). It acts as a chimney and you can see the numbers go down right away. If you close it again, the numbers bounce and goes back to slower cooling.

Cheers

PS: it would be interesting to get a hold of one of this puppies: http://www.unbeatablesale.com/cppf2309....u=CPPF2309

I've also looked at omega.com but the digital pressure gauges are $300+. I am happy were I am in terms of performance but I wonder what the numbers are and how much they affect the performance. I think the meter should be placed just before the basket (if anybody with $$$ wants to try jeje).

I'm wondering how you get such fast roasts without your ET going through the roof and the roasts tasting ashy.

I've also looked at omega.com but the digital pressure gauges are $300+. I am happy were I am in terms of performance but I wonder what the numbers are and how much they affect the performance.

You can make a very cheap pressure measure device by using a section of clear tubing (Tygon, for example) bent into a "U" shape and filled with enough water so that the water level extends to the straight parts of the "U". The water level on both sides of the U will be the same if nothing is connected to either end. Now make a hole in the duct that you want to measure pressure in and press one end of the tubing against the duct so that it seals around the hole. You can use tape if necessary to seal any gap. If the pressure inside the duct is lower than atmospheric, atmospheric pressure on the other side of the U will push down and the water level will rise on the duct side. It is very sensitive. The calibration is such that if you a vacuum on one side and atmospheric pressure on the other, the difference in column height would be 30 feet. I expect you will see differences of a few tenths of an inch. Measure the difference in column height because that difference is directly proportional to the pressure in the duct.

Dennis

Arpi wrote:What speeds cooling the drum after roasting is opening the little top door (beans feed). It acts as a chimney and you can see the numbers go down right away. If you close it again, the numbers bounce and goes back to slower cooling.

I've experienced this as well (although opening the bean exit door rather than the entry door). It is my impression that the temperature displayed will more accurately reflect the drum temp if all of the various doors are closed (as if roasting).

(This is on a 2kg Has Garanti)

I haven't noticed whether opening the exit door actually speeds the cooling or just gives the impression of doing so, but it would be worth testing to find out - it usually takes me ~10 minutes to lower and stabilize the drum temp between roasts, and anything that would speed that up would be quite welcome!

Regards, Henry

Hi Jim.

The Kenya beans (from the graph I put earlier in this thread) are good even for espresso. I guess they can take a hit. No ashy taste. Today I did two types of decaf coffee (~10 mins roast time) and tomorrow I'll give them a try. One of them is Donkey blend (decaf) from SweetMarias and the other Colombia WP Decaf Hulia Pitalito. Those beans should be pretty sensitive to ashiness. Oh, I also did some robusta from Panama.

Hi Dennish.

TX for the nice idea. It is attractive to try as it needs little investment. I have placed two restrictions in the roaster. One is the dryer sheet and one the exhaust. One is before the fan and the other after. Don't know if the placement of the restriction before/after makes a difference but it would be nice to try and see. With coffee toys is is pretty easy to get carried away into crazy territory.

Thanks

Hi hbuchtel.

I haven't measured the cooling time but 10 mins sounds reasonable. I usually clean stuff (vacuum) and weight next batch, etc.

Cheers

hbuchtel wrote:it usually takes me ~10 minutes to lower and stabilize the drum temp between roasts, and anything that would speed that up would be quite welcome!

Dropping in the next batch of beans should do it nicely; at least it works at all the roasters I've vistited. Once the beans are in, the bean temperature sensor drops like a rock (obviously), and you have a minute or two to get the environmental temperature sensors on track as well.

another_jim wrote:Dropping in the next batch of beans should do it nicely; at least it works at all the roasters I've vistited. Once the beans are in, the bean temperature sensor drops like a rock (obviously), and you have a minute or two to get the environmental temperature sensors on track as well.

Well boy... if I could get that working it would be great! I find repeating a profile difficult with less than 2 minutes of stable bean probe temp before dropping the beans in, but I will definitely try it out.

Regards, Henry

Arpi wrote:OK. Got it. I read somewhere (sweetmarias?) that ET was the air temperature inside the drum but I guess it can mean other things too.

another_jim wrote:That would read lower than the beans by the end of the roast. To work right, you are looking to measure the temperature of the bean's proximate source of heat. That is the drum itself and the air flowing along its surfaces.

Jim, in this article by Terry Davis (of Ambex) he recommends placing the ET probe within the drum out of the airflow. Do you have any thoughts about the pros/cons of that placement vs your placement?

Regards, Henry