Lambretta58 wrote: Thanks! It does appear so.

Took some time digging and searching to find what I needed. The hardest part for me to source was the drum. I finally found some 6" schedule 10 ss pipe at an old employer of mine. The rest was just being creative.



The reason is the vanes need to go to the front and the back to mix the beans so they don't all pile up on one end. Therefore no reason to reverse to get them out.



I have a three vane drum so I need to keep the rpm higher to keep the beans moving to throw them. I have gone as low as 65rpm but seem to get my best at 80-85 rpm.

I was really lucky and was able to get my 8" (8.625od) schedule 10 stainless pipe for free from a customer that does piping for cruise ships. It was just piece of scrap as far as they were concerned.

I just took my entire machine apart today to rebuilt the drum with the addition of reverse turbine blades. In the past Anytime I did more than 24oz I noticed I had to slow down my roast time otherwise the beans in back got done quicker than the front beans. Mixing took longer the more beans were in the machine. I just did a test run on 19oz of washed Papua NG. We will see what the effect is on bigger batches but so far it has drastically effected my machine

Less RPM is needed for convective heat 40-50 rpm vs 60-70 rpm prior

Less heat is needed for drying phase. same heat dried the beans in 3min vs 5min

The beans still looked very evenly roasted

Sorry for the bad pic. Should have taken it with the drum out

Front view of my drum, turning clockwise. The BT probe is placed on lower left side, ET on upper right, a few mm away from the blade, getting 50mm into the drum, just before the "cross". The outer blades take a quarter space of the drum each, they are bent so they stand in right angle from the back to the front. The left side of them is clean so beans can move without obstacle to the front (like a ramp). Because of the turning, they are moved a little "up the wall" on the left side (passing the probe) and fall into the center around "1100". The short and steep inner blades then push them to the back. This really works well. When the door opens, the "walking up" eases, the beans don't get in touch with the inner blades anymore and rush out instead.

At first, I thought of contrary blades as well, but it takes too long for the beans to get out when the door opens, because they constantly tumble around, don't get into a "flow".

My BT probe is similar at 60mm I believe.

Lower forward blades are extremely similar to your setup.

Your contrary reverse blades are a very cool design. Enough to mix but not hinder.
I can't comment much on drop yet except that it took under 7 seconds for the beans to dump this time. That is an increase of a few seconds over forward only blades but totaly acceptable.