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pisanoal wrote:



I tried my new angled plate design and it helped a little but was still having issues with the temperature. I also had to turn the air back up at the end of the roast to keep beans moving which i thought was really odd. I hypothesized that maybe the dlow falloff at the pressure required to loft the beans was significant enough to not be able to deliver enough BTUs.

I tried two blowers tonight and finally had a successful roast! I was able to keep my ROR where i wanted and the ET stayed under 500 degrees. I was stuck on having enough pressure because that seems to be what people think is most important, but the pressure vs flow curve definitely comes into play when pushing the limits of the blower pressure.

The blower you recommended is almost twice the CFM at close to the same pressure so i think it would act as my two blowers. Do you see any issues with this? How quiet is the blower you recommended? Looks like a low power draw too? Do you have a source that isnt $200.

allenb wrote:

The angle on the 1+ bag Sivetz I used to roast on was somewhere near 45 degrees and the throw of the beans was up and not toward the vertical wall.

pixelsmithy wrote:



This makes sense because air will follow the path of least resistance. It isn't going to turn a corner just because you have tilted a round hole. Instead the air will continue to flow in the same direction, only the round hole has now become elliptical, thanks to the tilt you have put in the perf plate. This means you are effectively reducing the amount of hole-square-inches and so may need more holes than you would have in a flat perf plate, to achieve an equivalent air flow.

pisanoal wrote:

Then we decided we should add a baffle in the furnace section to keep the direct hot air from going straight through perforations. Instant success!

With the furnace baffle I immediately noticed two things: 1) I was having to push gas flow a lot higher at the same air flow to reach roasting temps on my ET and 2) The ET trend was much, much smoother. So I concluded that I was getting some localized areas of very hot air, but overall not getting enough heat.

PhilH wrote:

Sorry Im very late on this thread
Im with Tamarian on trying the steeper angle on the ramp

My Roaster is similar and maybe some comparisons could be helpful
I have a 5kg FB using 6? cylindrical RC and Burner with 45deg ramp and flat perf plate
https://forum.hom...ad_id=5296
I measure ET about 1cm below perf plate and ET is often measuring around 150C(270F) above BT
I measure BT about 50% of the bean mass height and about 5cm from the ramp and well out of the main spouting airflow.

Its notoriously difficult to understand with certainty the fluid/thermodynamics of a specific FB roaster geometry (esp wrg to Temp measurement). I measure peak ET about 350C(662F) which would seem to theoretically break ?the rules?. However I know there is a very significant temp drop as soon as the heated airflow crosses the perf plate which is difficult to measure accurately. I am comfortable this likely puts me back inside ?the rules?. Tasting (as Tamarian points out) is a great way to assess/confirm whether changes result in improvement or deterioration of roasted beans.

I use 2x cheap VC blowers ? one was not enough) and use a long burner chamber approx 750mm (30") from burner to perf plate (probably overkill) with a baffle plate to promote turbulence / mixing of heated air prior to reaching perf plate. Leaks prior to the perf plate (even small ones) are easy to miss and will mess up bean movement and lose a lot of heat.

Sounds like you have got it largely sorted now.

Husamka wrote:

If you noticed, your beans are falling in the middle of the column. it should be blown to the left end so it will smoothly slide on the 45 degree plate. If you can add curved plate in the top as a trial similar to the attached design.

Edit, Oops you already have the photo.