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snwcmpr
09/18/2019 4:09 AM
JavaBob ... You will get more response if you post a question on the forum rather than the shoutbox.

Mathew
09/17/2019 5:50 AM
check out the Hive Roaster!

JavaBob
09/16/2019 4:03 PM
Has anyone used a Leister hot air blower to roast coffee and if so, which model did you use? What was your experience like?

JavaBob
09/16/2019 3:53 PM
Source for customable borosilicate glass cylinders for use as a roasting chamber?

shoron
09/06/2019 7:25 AM
how to make medium raw colored beans to dark ?

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3d Printed Fluid Bed Roaster
greencardigan
Great circulation. How long did the 12oz roast take with your single element? Was it 1600W or did you change it?
 
Linnaeus
I believe it's a 1680W element. The roast took 14 minutes, but ran at only an average of 940 watts. I used a ramp programmed to slowly bring the beans up to temp over 14 minutes, so it seems that it could have been quicker with a more aggressive ramp.

This design may be slightly more efficient than others, as the element is encased in insulating refractory material rather than heat conducting metal. Similarly, the bowl of the roast chamber itself is insulating and has a high heat capacity, it is room temp where it meets the plastic base, and only reaches about 130 degrees near the joint with the Pyrex tube. Additionally, the topper increases internal pressure in the roast chamber and prevents hot air from venting out the top too quickly.

Cupped today and happy with the result. Fuller body than my previous attempts with these Brazilian beans.

When the heat element is switched off the beans are cooled to 100c within 15 seconds and 40c within a minute or so. I do need a good way to eject and am wondering if the vacuum pressure would be enough to do so if I capped the top with a tube inserted into the bean mass.
Edited by Linnaeus on 02/20/2018 2:50 AM
 
http://www.linnaeus.photography
Linnaeus
A quick modification - I added an aluminum plate to the rear of the chamber. Beans were circulating well in the front but we're stalling quite a bit in the rear. The new / steeper wall is giving a much better motion to the bed.

In the future I would not experiment with an off axis inlet unless all of the walls were significantly steeper than they are in my roast chamber.

 
http://www.linnaeus.photography
Husamka
Great efforts. I would be interested to buy from you the ready roasting chamber as you already have the molds. it is not wrong to sell them to cover your costs. but the size is too small. thanks
 
Linnaeus
Thanks Husamka - I'm not sure that it's really ready for mass production, but maybe I'll make a few batches once it's optimized.

In other news, I added a small disc in the center of the roast chamber inlet to agitate the air and fluidize the whole bed a bit more (rather than spouting just in the center). This has made the roasts more even and predictable, but has reduced the maximum roast volume down to 180g or so.

The issue is airflow and the 120W vacuum just isn't enough. I've printed some parts to add a 6W 80mm fan to the vacuum intake. Curious to see if an Axial/Radial combo will be more efficient. At the very least, the benefit is that I can turn off the vaccuum motor (which is obnoxious) and just leave the 80mm fan running while the roaster cools off (after ejecting the beans).

So this would be an axial compressor into a radial compressor. The thinking is that the radial compressor is optimized for high pressure, but maybe not high airflow. Adding an axial fan to the inlet will drive SLIGHTLY more air into the radial compressor, hopefully raising the static pressure (bean mass) at which it stalls. They may have an interesting interaction... the axial fan stalls readily with any back pressure, but in this configuration it will actually have a pressure deficit... I have no idea what impact this will have on the performance characteristics, because all the charts I can find show a positive static pressure at the fan outlet.

At the worst, it's just additive - which would have a minimal impact as the pressure capabilities of the axial fan are so poor.

I'm no physicist...so this is really some bunk science going on here. I'll let the results speak for themselves once this is testable.

Best,
Rob
Edited by Linnaeus on 03/27/2018 5:46 AM
 
http://www.linnaeus.photography
Linnaeus
So, no surprise...there is no magical pressure gain in stacking an axial and radial fan in series. The axial fan had almost literally no effect.

Then I remembered that I had a few 24V - 0.83A squirrel cage fans lying around. I printed up a quick adapter for one and added it to the intake before the vacuum motor. This did have a noticeable effect, allowing me to loft approximately 20% more beans by weight.

Lesson learned - compressor pressure is roughly summed in series. The exception is when a compressor is outside of its "stable" pressure rating (static pressure too high) - in which case the compressor will be stalling. Adding another compressor in series will bring it out of stall and then the gains will be much greater.

i.imgur.com/xPa1vJR.jpg

Another fun discovery: A bowl of water makes a surprisingly good chaff collector:

i.imgur.com/vaV7lNG.jpg
 
http://www.linnaeus.photography
Linnaeus
Added a conical separator for chaff management.

 
http://www.linnaeus.photography
greencardigan
Nice! Is that one of the small cyclones from ebay?
 
renatoa
Yep, looks as mine, different cased but same.
eBay search terms: "Aluminium Cyclone Separator"
 
Linnaeus
It is - works really well too. I used a paint can from home depot as an outer housing. Allows it to be mounted to the top of a mason jar. I just cut a hole in the bottom and bolted on a mason jar top minus the inner sealing plate.
 
http://www.linnaeus.photography
ThinkJunket
This project was so amazing! So glad to see that you have gotten it to work in the end.
 
Linnaeus
Hi all,

Since building this I have moved to Sweden. I had to adapt the roaster to 230V anyway, so I thought it would be a good opportunity to rebuild it.

I've gone with a more modular design this time. One of the biggest issues with the last iteration was that the roast chamber and heating element were one unit. This made it difficult to experiment with different roast chambers. Additionally, it was difficult to experiment w ith perforated plates as there was no good method for affixing the perf plate to the chamber. Finally, I used four bolts embedded in the concrete for the lower blower mount. This made it difficult to get a good seal and was a bit fiddly.

This time I've gone with a 3 piece modular assembly.
1) The upper chamber is the bowl which will hold the beans and the pyrex tube. I've gone with a steeper bowl design as I have an over-powered vacuum motor and heating element. Last time around I did have an issue where beans would not always slide smoothly down to the spout.
2) The middle chamber houses the heating element.
3) And the lower chamber attaches to the vacuum. You can see where the wires will be routed inside of the ABS cuff.

The lower 2 modules will be inside an enclosure, while the top module will sit flush with the enclosure surface.

All 3 modules will be coupled together using 3d printed ABS cuffs and steel bands. In the last design I had issues with pressurized air pushing through the silicone seal. I think this will work well to keep the parts together and also provide an air tight seal. I am a little bit concerned that the upper cuff may exceed the working temperature of 105C. If this happens I will add a fan in the enclosure to cool this area - or route the vacuum intake so that it draws air over this part of the assmbly.

i.imgur.com/vA2d9jn.png

i.imgur.com/qCUe9Ym.png

i.imgur.com/kI2EC5W.jpg

I've added an extra inset to the heating element chamber which will provide a corrugated air gap between the element and the side walls. I am hoping that this helps limit heat transfer to the concrete. The corrugation is to allow for more expansion of the material without cracking and a larger surface for deflection of heat.
Edited by Linnaeus on 01/22/2019 1:56 AM
Robert Linnaeus
www.linnaeus.photography
 
http://www.linnaeus.photography
Linnaeus
The pours have set. You can probably see that I added two bent nails to the lower pipe connector in order to anchor it into the refractory concrete. In hind-sight this lowest piece could have been made from ABS as it will not be exposed to high temperatures and will be actively cooled by the stream of air from the blower.

The pours came out clean - especially the upper roast chamber. I used less liquid than I have in the past to ensure that the part would be as strong as possible.

I've also gone ahead and drilled the hole for the temperature probe before the concrete fully cures.

i.imgur.com/ZRcMFR6.jpg

i.imgur.com/9s4qBRj.jpg

High temperature gasket silicone will be used between each module to ensure an air-tight fit.
Edited by Linnaeus on 01/22/2019 1:59 AM
Robert Linnaeus
www.linnaeus.photography
 
http://www.linnaeus.photography
Linnaeus
i.imgur.com/xToCIkt.jpg

Here you can see one half of the lower ABS cuff. The two halves will be sandwiched around the concrete parts and bound together with an adjustable steel band wrapped around the entire assembly.
Robert Linnaeus
www.linnaeus.photography
 
http://www.linnaeus.photography
CK
Good to see you're building again. I enjoyed your past posts and creativity... your new iteration with improvements looks good. Will this be PID or Artisan controlled?

For your high temperature 3D printed parts you might consider regular PLA. If you anneal regular cheap PLA it has a higher heat tolerance than ABS... something like 165C according to what I've read. There are shinkage factors to consider in designing your parts, but it is a good option. I used 3DK TOP filament. It is pricey, but this PLA can resist temps 230C after annealing.
 
Linnaeus
Hey CK - thanks. Coming from you, that's a real compliment.

I have the PID working, so I might fire it up with that to test everything out; but i'd like to give artisan a shot.

I have a raspberry pi and also some Arduino like boards
I'd love to run artisan on the pi headless and control it from my phone - but I'm having a hard time understanding how to use it to control the gpio pins on the pi.
Robert Linnaeus
www.linnaeus.photography
 
http://www.linnaeus.photography
salperta
Howdy Linnaeus,
I know it's been a few months since you last posted, but I was wondering how you connected your chaff collected to the top of the bake-a-round. It looks like a nice connection. And with the bake-a-round not sealed to the concrete, how do you avoid air leaking out from around where the Pyrex meets the concrete?
Thanks so much -- this project is a great inspiration.
 
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