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Thread: Dryer... roaster

  1. #1
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    Dryer... roaster

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Friday afternoon and my mind is wandering, which is inturn leading to a lot of head smacking "magic moments". Anyone whos interested in chocolate grinding feel free to have a look at my thoughts and hopefully add your own in the mmmmm..... chocolate! thread in the wishing well.

    Anyways, long story short I was thinking a washing machine could make a good chocolate grinder. Then I was googling washing machine motors online when I noticed a combined washer dryer and thinking... maybe I could roast the beans and grind them in the same machine if I tore out the 150 degree thermostat they put in driers and replaced it with either a higher one or even better a programmable one.

    Then I sat in a classic fridayitis stupor for 10 minutes until the penny dropped.

    Chinese clothes driers can be bought new for around $200 these days, and take 5 kilo loads with ease. Plus if you get a side load one with a clear front door you can watch the clothes spinning. They have inbuilt agitators and timers.

    Whats to stop people from buying a cheap drier, ripping out the wussy clothes grade thermostat, and fitting a heavier duty thermostat?

    Thought perhaps the chaff would be a problem, but driers all have lint extractors now... is it me, or is the idea just crazy enough to work? Im starting to feel rather daft about putting so much time into modifying a bbq for the purposes... kinda hoping someone is gonna point out some obvious flaw in my plan of changing a thermostat and having a super cheap, premade high capacity roaster.

  2. #2
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    Re: Dryer... roaster

    mmmmm..... I guess a few concerns.
    1 - is it food safe? what chemicals would leach into the dryer at 200+ Celsius
    2 - Can the unit handle 200 +Celsius without degrading
    3- Can the heating element produce enough heat?

    To be honest i wouldnt really look into it any further unless you just wanted to salvage one for its drum.

  3. #3
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    Re: Dryer... roaster

    How easy would it be to get the beans out?
    That seems to be the biggest problem, but then again i am not known for fiddling with 240v appliances.
    Just wondering if it would get hot enough if the the thermostat was changed and would it be reliable at higher temps.
    Just my second crack after reading your post .

  4. #4
    Sleep is overrated Thundergod's Avatar
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    Re: Dryer... roaster

    Ive pulled apart a few driers over the years.

    Chaff - not a problem; youd install the vent kit and remove the filter so that the chaff vents to outside the drier.

    Change the thermostat - easy enough; the problem I see though, is that the element probably cant produce enough heat for roasting and would burn itself out.

    The plastic viewing window also would probably not be able to stand the extra heat, let alone all the other plastic bits on driers these days.

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    Re: Dryer... roaster

    Okay, as fortune should have it a coffee ninja attacked the drier and pulled it to peices. I thoroughly discourage pulling apart whitegoods yourself as it may anger family members who claim ownership of said whitegoods... but if one of those darn coffee ninjas attack then you might as well profit.

    Am very pleased at what was uncovered. The drier is almost entirely made of metal, plus the wiring is heat shielded.

    Four apparant issues:

    Plastic door. Unbolt door, bolt on heat tolerant replacement.

    Thermostat. Bypass thermostat and heater. Point heat gun into intake to test, look at getting some kind of temperature controlled setup if going permanent.

    Plastic agitators. Unbolt agitators, bolt on some angle iron replacements.

    Plastic lint catcher filter. Pull the lot out and let the chaff just blast out the exhaust port rather than catch it. If I really want to catch it use some mesh.

    Couple of pictures attached of what was uncovered. Still thinking this one through, but Ive got a solid metal drum, all plastic components are just bolted onto it... thinking upgrading the heating element and pulling the plastic off and itll be a runner.










  6. #6
    A_M
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    Re: Dryer... roaster

    Sorry.. Your going to loose so much heat for many number of reasons...

    1: No thermal mass

    2: Lots of Air

    3: Thin walls

    4: bean mass ??

    5: Drive belt would fail

    A hotTop is small and is flat out doing what it needs to do with 240V and a single element.


    You would need 3 phase and teh thing would fall apart/ cook before the beans...

    Great thought... BUT!!!!

  7. #7
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    Re: Dryer... roaster

    I agree with AM, your idea is brilliant!, this CS way of turning everyday appliances into coffee peripherals is amazing to watch, the popper, the corretto, the KK, and now the Dryer!......nothing in the house is safe, i say give it ago, more heat may be necessary and you may fail......but hey, the fun is in the trying i think!
    good idea! and good luck!

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    Re: Dryer... roaster

    if you do it make us some video and post it up.

    but in all reality i think you should just buy a 2 or 5kg roaster

    imo by the time you mod the crap out of a dryer it will be $$$$ down the drain

    fun ideas but, cruise those Perth streets for some curbside dryers and have a go..... I had a laugh

  9. #9
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    Re: Dryer... roaster

    would you have to slow the drum too?, dont know too much about drum roasters, just a thought.....

    AM is there any way you could add thermal mass to the drum?? in a way to retain heat in the drum without losing the holes??? hmmm i suppose it would also add significant weight to the drum and more pressure on the support shaft and bearing thou...

  10. #10
    A_M
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    Re: Dryer... roaster

    Quote Originally Posted by 7E7A5C4545405F4847290 link=1247817355/9#9 date=1247876990
    would you have to slow the drum too?, dont know too much about drum roasters, just a thought.....

    AM is there any way you could add thermal mass to the drum?? in a way to retain heat in the drum without losing the holes??? hmmm i suppose it would also add significant weight to the drum and more pressure on the support shaft and bearing thou...
    Yea... Place it inside a massive cast iron body.. and then when teh drum burns out after haff way through the first roast, replace it with SS. Then after teh bearings all seize due to hear put in bronze or another bearing set that can stand teh heat..

    Thus...

    This is the reason that roasters over about 800g to 1Kg start to cost $$$..

    Heat is a great tool... But it needs true management if it is to perform the work / job as expected.

  11. #11
    Senior Member Koffee_Kosmo's Avatar
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    Re: Dryer... roaster

    I thought about a clothes dryer about 2 years ago

    Apart from what AM has said already
    Volume to heat ratio is also a major concern

    KK

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    Re: Dryer... roaster

    Ahh well, what I was hoping to be an elegant solution has become involved to the point where its gonna have to wait. But no harm in discussing what I found.

    Firstly a little research: http://www.cpsc.gov/library/foia/foia03/os/dryer.pdf a cpsc report on dryers. Gotta love the american government. Short rundown of it is that a heater unit in an average dryer can pump out about 1000 SFPM of air at 300 degrees and maintain for 20+ minutes. Now when the amount of air being output is dropped to 800 SFPM to see a jump in the temp to about 370 degrees. Unfortunately the research paper then jumped to completely stopping the output which saw the temp immediately jump to 550 degrees and start cycling on a thermo cutout.

    So then were left looking at efficiency. Dryers work on a convection heating principle so dont need to worry about thermal mass, same as a coretto. But we do need to worry about efficiency. After the initial stabilisation curve, cold air out hot air in plus warming up drum etc it appears the average dryer will be injecting air at 350 and the air is leaving the drum at 50, injecting air at 400 it leaves at 100. Basically were dealing with a massive heatsink. Given the surface area of the drum plus the fact its spinning means its gonna drop heat at a horrific rate. If a decent roast curve is to be managed itll mean having to insulate the drum. Id be tempted to try a layer of foil/bubble insulation... Mainly coz I have a big roll of it left over.

    Concerns for failure of the thin wall steel are fair enough, but the temperatures being dealt with are to low. In the 200 to 250 range Im looking at a 1% reduction in integrity. 250 to 300, 5%. The dropoff point for thinwall is generally around 450 degrees where itll lose 40%. Of course that depends on the design of the drum and the alloy of the metal.

    Bearings are an interesting one, and Ive got no idea what the average bearing fitted to a drier would be... big question mark there.

    So what I think its boiling down to is:
    Replacing door,
    Insulating drum,
    Relocating thermostat to stop it tripping,
    Controlling internal temps by restricting air intake,
    Possible swap out of bearings
    Possible swap out of drivebelt.

  13. #13
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    Re: Dryer... roaster

    I recently rebuilt our electric clothes dryer. I replaced the drive belts and idler/tension assembly, seals, painted the drum, replaced the heating element. etc. As others have stated, it would be a pretty big waste of time to try to adapt one (electric or gas) for coffee. Mush easier to start from scratch, imo..... fwiw....

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    Re: Dryer... roaster

    Oops sorry kosmo, posted at same time. By volume to heat ratio do you mean the volume of air in the drum?

    Yeah its not ideal, the sheer volume of coffee thatd need to be roasted to justify the space would be way more than a hobbyist needs. However with insulation I think a regular dryers heater unit would be up to the task. 1000 SFPM of air at 300 degrees is a lot of hot air, nothing on parliament mind, but still. If the drum could be insulated enough to stop the giant heatsink effect, the heater unit can pump a lot of hot air in.

    Essentially wed be dealing with running a correto in a room the size of a dryer drum. The heatgun is further away from the breadmaker, and the bowl of the breadmaker is a lot bigger. But that room is gonna get hot quick. Trick will be making sure theres insulation to keep the heat it, and controlling ventilation into the room will regulate the heat.

  15. #15
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    Re: Dryer... roaster

    Quote Originally Posted by 0702110E1017110C0D04630 link=1247817355/14#14 date=1247890677
    Oops sorry kosmo, posted at same time. By volume to heat ratio do you mean the volume of air in the drum?
    Yes
    However if a roaster has an outer heat chamber then that should be included in the overall volume
    Go to this site to calculate the volume of a cylinder

    http://www.online-calculators.co.uk/volumetric/cylindervolume.php

    I had to get my roaster down to a total heat chamber volume of 11 litres or less for it to be viable & controllable

    KK

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    Re: Dryer... roaster

    Behmor Coffee Roaster
    An imaginative concept.

    My 2dth:
    When no ones looking take the gas burner out of your storage gas hot water service and rig it under the drum should give the heat boost required to approach roast temp but may need a second one to actually roast.
    Large scale, high energy requirement and temperatures are very demanding.
    You may need a new apartment for prototype 2

    Lindsay



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