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Drum roaster in glass tube
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| witoldb |
Posted on 06/26/2012 11:53
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Hello from Dubai
I'm building drum coffee roaster from my junk parts.
I had to buy following components:
140 mm OD x 240 mm long glass tube from candle light stand ($16)
SS dish with cover ($4)
1200W popcorn maker ($16) to use fan and heating coil
Bread toaster ($24) - using only mica sheets for heating coil support
Small piece of brass sheet ($14)
12V gear motor ($7)
Chinese PID controller ($25) for BT readings
I had PID controller with 4-20 mA output but could not source SSR with linear input so made one myself(for ET control).
This is still work in progress, all controls are in separate box which I used earlier to roast in popcorn maker.
I could roast only 60 g of greens and this was with additional fan in the base of the popper. Without additional fan I had to stir the beans with a wooden stick to maintain their circulation.
I did few roast with the drum roaster with up to 300 g greens.
First roast took too long - 46 min to beginning of 2nd crack even after pushing the ET to 410 deg C.
Later I've insulated the glass tube with Gore teflon gasket sheet, reduced fan voltage and managed to reach 2nd crack at 17 minutes (ET was 380 deg C).
I think that ET probe is not measuring actual air temperature due to radiant heat - the heating coil gets quite bright (orange color).
I'm afraid that the coil will burn through quite quickly so started to install additional blower/heating coil assembly from my old popper (on the inlet duct) to preheat the air and reduce the load on main coil (the one inside glass tube).
Will appreciate any comments and advice.
witoldb attached the following images:
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| ginny |
Posted on 06/26/2012 12:04
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Super Admin
OWNER
Posts: 2762
Joined: 10/24/2005 11:33
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Well, that is one sweet looking roaster you made.
Got a prototype to send over the water to me.
I will be sure to write a great review.
good work.
ginny
Ala di Vittoria La Valentina,
Solis 5K, Aero Press, Mazzer Mini, Hot Top 8828 B 2K,
Quest 3, TC4C set up to use...
Sun-swept beaches with a light wind blowing...
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| yamhill |
Posted on 06/26/2012 12:33
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1/4 Pounder
Posts: 93
Joined: 12/18/2009 22:16
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Wow. That is an impressive first post.
So does the unit have two coils now, one in the popper unit at the top and one inside the glass?
I'm looking for an SSR alternative. What type of circuit are running?
John |
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| freshbeans |
Posted on 06/26/2012 12:36
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Super Admin
Reasonable
Posts: 1400
Joined: 03/06/2010 11:10
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Very clever use of materials! Thanks for posting. The second image appears to be an old vacuum fan...repurposed?
Nice machine! -Scott |
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| witoldb |
Posted on 06/26/2012 13:34
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Second photo shows mica sheets with spacers supporting heating coil.
I'm still busy with installation of the 2nd coil, have to drill accurately 6 holes in the popper heater element/blower housing to match the flange on top of the ducting (2nd popper housing I've got is different OD).
I made use of this dimmer schematic:
http://pcbheaven.com/circuitpages/Voltage_Controlled_AC_Light_Dimmer/
Resistor R13 should be 250 ohms to convert 4-20 mA PID output to 1-5 volts.
You have to set PID to cooling control as this circuit is fully on at 1V and off at 5V.
I can post PCB board in Eagle or pdf format if you need one.
Better alternative I will use next time will be schematic from ESP site:
http://sound.west...ect62c.htm
as 1-10V corresponds to "off - fully on" and PID can be set to heating mode.
You will need oscilloscope to adjust both circuits, even simple PC-based will be fine.
These schematics are only ones with linear voltage inputs I could find on the web.
Edited by allenb on 06/27/2012 17:19
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| allenb |
Posted on 06/27/2012 17:31
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Super Admin
Fix It Man
Posts: 1477
Joined: 02/23/2010 19:51
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Very very nice! High tech lab precision in a small coffee roaster. Please explain convection air path. I'm assuming it exits the convection heater, travels around the rear and into the drum then exits via fill chute? Wondering about plans for chaff handling.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| witoldb |
Posted on 06/28/2012 02:34
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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This is general layout I have in mind.
I need to have good smoke/chaff exhaust as here it is difficult to roast outside in summer (up to 50 deg C midday, above 30 at night).
In a next few days I will try preheating coil and/or stretch main one to be between 2 baffles to reduce radiant heat.
Also will try to relocate main ET probe.
Edit: Drawing in following post. JD
Edited by John Despres on 06/28/2012 04:47
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| witoldb |
Posted on 06/28/2012 04:08
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Here's the drawing.
witoldb attached the following image:
Edited by John Despres on 06/28/2012 04:48
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| John Despres |
Posted on 06/28/2012 04:49
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Super Admin
Posts: 2083
Joined: 01/09/2008 07:55
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Best I could do for you without downloading the image and risk messing it all up.
Hope that helps.
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
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| seedlings |
Posted on 06/28/2012 09:49
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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Oh heck YES! This is one impressive roaster!
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| tamarian |
Posted on 06/29/2012 07:41
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1/4 Pounder
Posts: 96
Joined: 01/21/2012 00:44
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Looks awsome, especially with limited sourcing/supplies for hobbyists in the region! Any chance of a video? :) |
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| witoldb |
Posted on 06/30/2012 14:04
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Glass tube has failed.
Heater wire coils were too close, sagged due to heat and touched the glass cousing it to crack.
witoldb attached the following image:
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| witoldb |
Posted on 06/30/2012 14:07
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Replaced the tube with a cylinder made from SS dust bin.
Rivetted it with 1 mm copper wire.
witoldb attached the following images:
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| witoldb |
Posted on 06/30/2012 14:09
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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I've added RTD sensor on inlet duct
witoldb attached the following image:
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| witoldb |
Posted on 06/30/2012 14:12
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Modified main ET sensor by adding an mica shield on top of it.
Also increased heater coils spacing by stretching it and laying it in 2 rows.
witoldb attached the following images:
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| witoldb |
Posted on 06/30/2012 14:21
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Current state of the roaster.
Covered with 2 layers of fire blanket and 1 layer of teflon.
I will cover it later with SS brushed sheet from another dust bin.
I made short movie showing 300 g beans rotating in the drum (without outer drum and no heating) but I'm not sure how to upload it.
Still have to complete wiring, hope to roast in next few days.
witoldb attached the following images:
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| tamarian |
Posted on 06/30/2012 14:53
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1/4 Pounder
Posts: 96
Joined: 01/21/2012 00:44
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The loss of the glass chamber, while unfortunate, allows for chaff collection by cutting a small opening at the bottom of the dust bin(s) for the chaff to fall through into a small collection tray...
re: video, upload to youtube or dropbox. |
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| witoldb |
Posted on 06/30/2012 21:17
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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Thank you for the suggestion, didn't think about it earlier.
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| witoldb |
Posted on 07/01/2012 13:39
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Newbie
Posts: 35
Joined: 05/07/2012 05:15
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I've uploaded short video on Youtube:
http://youtu.be/OA615ptJx3I
Home: Gaggia Classic, Mahlkonig Vario
Work: Gaggia Color, Hario Slim
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| jkoll42 |
Posted on 07/01/2012 15:20
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Pounder Plus
Posts: 530
Joined: 02/14/2011 08:25
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Very cool roaster. Look forward to seeing it as it progresses.
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
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thanks for joining.
Marco.....