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Thread: A few questions for building a new roasting machine

  1. #1
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    Question A few questions for building a new roasting machine

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I have never roasted coffee before and will be within the coming weeks using the popcorn machine. I currently go through 1KG of roasted beans in 2 weeks so roasting 500g on a weekend with a popcorn machine is going to get tedious which is why I haven't started for years.

    But I have an idea for a machine, I've had the idea for quite a while but have a few unknowns. The machine will be gas fired but can be electric, I just figured I might get better control with gas. My main two questions are:

    1. What is the ideal temperature to roast, my oven will hold approximately 20-25 litres
    2. At what speed should the drum rotate? Would 30-60 RPM be efficient?

    I've still got to figure out the most effective way to cool my beans once roasted, but I've got a long ways to go to sort out my design first.

    Any opinions are greatly appreciated.

  2. #2
    Senior Member coffeechris's Avatar
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    I dont mean to shine the light away from your original question, however have you thought of roasting with a bread maker and a heat gun? The set up is called a Corretto. There is plenty of info on the site to build your own. On top of that there are many people on here to give you advice about it. I manage to roast 450g of beans in one turn. batch takes between 11-16 mins. It cost me under $60 to set it up.

    All that aside i like your idea of building a roaster, i hear there is alot involved. Dont let that stop you though. i think its a great idea and good luck with it.

    Regards,

    Chris

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    Thanks Chris, maybe I'm out of my league, but I'd be un-Australian for not trying to build something. If it flops I'll have the satisfaction of knowing I tried

    My idea is based on taking a beer keg, cutting it right down the middle and hinging the top and bottom. A shaft is inserted through the middle to serve as the axel. A couple of gas burners in the bottom with defusers serve as the heat source. I just have to figure out what sort of cage I'm going to use to contain the beans and how I can eject the beans quickly.

    I haven't heard of anyone making a beer keg roaster, though thought it might be a nice place to start.

    If it flops, which is fairly probable I'll crack on (no pun intended) with the bread-machine/heat-gun approach

  4. #4
    Senior Member coffeechris's Avatar
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    I like your attitude towards it, why not give it ago!! I believe there are a few people on here trying things like this. So if you can spend the time trawlling through the forum you might find some valuable information that will help you.

    Good luck with it all hope it goes well, at the end of the days its fun trying new things

    Cheers,

    Chris

  5. #5
    Coffee Nut fg1972's Avatar
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    I am very new to roasting & in the process of building my own mini roaster too.
    From what I understand & have experienced with a popcorn roaster fitted with a thermocouple probe, temperature ideally needs to be controllable from ambient to ~220 degrees.
    For example, gradually increase the temp over x number of minutes to ~180 - 190 degrees to achieve 1st crack, hold that temp for x number of minutes then gradually increase to to ~210 - 220 for 2nd crack.
    I don't yet know the effects of the drum rotation speed, hopefully one of the pro roasters will provide some advise.

  6. #6
    Life-long Learner DesigningByCoffee's Avatar
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    Hi Brett
    Certainly do-able - considering many of the variations we've seen come through here! (search for BBQ roaster :-)

    My only real thought is that if you are looking to do 500g a week (which isn't that much - a breakfast bowl of greens), a keg roaster may be overkill. A roaster the size of the keg, which would require a heat source to match, would be more suitable for roasting 10kg+ IMHO. That's a big week of shots!
    I'd concur with Chris. I personally use a Corretto, which is ideal for 300g-600g batches (I do 350g on a weekend for the week) or you could go to a KKTO (Turbo Oven) - handles up to 1kg per batch. These would seem to be the most suitable for your usage.

    And to keep the aussie spirit alive - both of these can be as simple or as pimped as your tinkering/engineering/size of your shed skills allow :-)

    Have fun!
    Matt
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  7. #7
    Senior Member sidewayss's Avatar
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    Give it a go. It would be a uniquely australian idea, just like the coretto and the KKTO.

    Plonk the keg on a stable platform. Knock a hole out of the top somehow to let smoke n heat escape. A hole underneath for fresh air.
    Install either electric elements or gas trains inside.
    On the open side, install a door with a window( this window can be also used as a source of fresh air to enter the keg) to view the beans (you're going to have to shine a torch into it to see them beans goin round n round).
    Middle of the door is the shaft linked to the cage and a handle on the outside for the purpose of turning the thing.
    The other side of the keg, knock a hole out and install a device to hold the other side of the cage a la Behmor.
    You will work out a way of pulling the cage to the door, open the door and then remove the cage to dump the beans for cooling.

    Don't forget the right bean cooler for whatever size batch you will be roasting

    Thought i'd give my 1 cents worth. You can then adjust to suit.

    Certainly the coretto and the KKTO is a good option as DIY projects, and these can roast large enough batches for your requirements, but like you said, you would like to create something that,s unique, and i wish you the best.

  8. #8
    Member themurphs's Avatar
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    Sounds like a plan!

    I have just started roasting on my Weber BBQ in a perforated drum (see picture) and i have discovered:

    1. Drum speed needs to be approx 30-40rpm.
    i have roasted at 5-10rpm and find the beans uneven in color. I have roasted at >60rpm and found i couldn't inspect the beans or hear the cracks.

    2. My drum is 300 mm L X 120mm in diameter.
    I can comfortably do 500g in this size, however as sidewayss as mentioned you need to have the right cooler to cool the beans down quickly.
    ( i am currently undergoing modifications)

    3. With the lid down and background noise, it can be difficult to hear first crack.

    I usually roast @250-270 degrees with the rangehood down, i get first crack @ approx 11-14min, and second crack @ 18-21min.

    I still have improvement ideas going through my head on roasting drum designs, but i am happy with the results so far.
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  9. #9
    Coffee Nut fg1972's Avatar
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    Can you adjust the speed using that motor?

  10. #10
    Member themurphs's Avatar
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    not that i am aware of,

    Mind you i haven't opened the guts of the unit to peek at what is inside

    This is my rotisserie motor ( 5-10 rpm).

    I am trialing a automatic curtain motor 24VDC ( 60 rpm), With a speed controller to get it down to 30-40 rpm.
    I finally got my shaft coupling from ebay china ($7) and will attempt to mount it all together soon.

    There is another guy (fatboy1999) who has used an old windscreen wiper motor, for a setup on a larger drum.
    Check the post titled "To any BBQ Roasters out there" for photos of his setup.

  11. #11
    Coffee Nut fg1972's Avatar
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    A few questions for building a new roasting machine

    Thanks,
    Do you preheat the BBQ?

  12. #12
    Member themurphs's Avatar
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    Yes,

    I preheat for 8-10min.

    Then place the whole drum unit in the BBQ.

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    Hi guys, thanks for the suggestions and I do apologise for being slow, I've been away and only just returned last night.

    My idea is to have the keg on its side with a hole for the gas burner at the base and a drum rotating along a horizontal axis. Basically I'd like to create a cute mini version of something like this machine: Toper TKMSX Shop roasters - YouTube (Toper TKMSX).

    At first I thought the drum should have holes, but the more I see the more I think it needs to be a solid cylinder and rely on direct gas burning on the side of the rotating barrel with a fan pushing heated air into the chamber, is this correct? Though what about the fins in this chamber, any idea on the orientation for them?

    My biggest unknown now is how to replicate that door to get the beans out of the thing. I may need to invert one end of the keg to make it concave to help keep the beans inside maybe?

    I've done a bit of searching on the interweb to try find what I need to know, I now roll around in bed thinking of how to do this. I'll try and draw something and post what I am thinking on here.

  14. #14
    Member themurphs's Avatar
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    Is this similar to what you are building?

    Mini Coffee Roaster W600 - YouTube

    Glen

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    Senior Member fatboy_1999's Avatar
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    themurphs (Glen); Thats a nice little kit that one, yeah, I'd like to build something similar to that. Though I was thinking of using a solid drum with the burners directly on the solid drum, what do you think?

    I still don't know how the beans escape so easily when the door is opened, any ideas?

  17. #17
    Member themurphs's Avatar
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    I dunno, Now you have got me thinking!

    Don't know if this would work, but off the top of my head.

    If you are using a Rotisserie rod you could mount it on a slightly upward angle with one end of the inside drum open.
    SO it is tilted upwards for loading the beans and roasting, Tilting Upwards Stops the beans falling out while Rotating.

    See Drawing "Loading And Roasting". (Not To Scale, Ha!)

    If the front of the keg is like this (See "Front Of Keg Idea"), you can hold the rod on a slightly upward angle while roasting, then when done, turn it all off, grab the rotisserie rod and move it down to the exit chute for the beans to drop out onto the cooling dish.

    Mount the motor directly to the rod and fix the motor holding the outside to stop it from spinning around with the rod. That way you can move the rod up and down on an angle. ("Motor Mount Idea").

    Then once finished, lift the rod and lower it down to the exit chute.("Unloading the Keg").

    You can cover the Exit chute while running, Have one of those lever things in the video. Mount an air vent somewhere for the smoke.

    Idea might be A bit extreme, apologies for that, i can go off on a different wavelength sometimes. if you can simplify the idea, great.

    Cheers
    Glen
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    No not at all themurphs, sounds like a good idea and I may incorporate something of the sort, though maybe with a universal joint as my current design/thinking has the motor fixed to the machine and not to the rod, this is so I can control the speed of rotation through either belt or gearing. I'll probably go for belt though as it's got the greatest flexibility as to where I mount the motor and away from heat source.

    I'm still sourcing my beer keg so don't know my exact dimensions as yet, just the ideas on a white board

  19. #19
    Coffee Nut fg1972's Avatar
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    Awesome idea themurphs.

    Fiorello

  20. #20
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    A few questions for building a new roasting machine

    I got my keg today, well, I had a head start from my dad who sourced it for me.

    My dad used to make these mini rotisserie ovens out of kegs and this is what gave me the idea as they are nicely self contained, he's given me one of these ovens he made, all I need to do now is source a basket and add a fan to blow out chaff.

    If anyone might know where to find a basket I'm actually looking for one with wire stile walls and possibly open ended, I want it open ended to allow the chaff to blow out through the end. I could source something and modify it.

  21. #21
    Life-long Learner DesigningByCoffee's Avatar
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    Ahhhh I see now! Good idea Brett :-)
    I was thinking you were going to split the keg, and go the "FZRR Baby Roaster" style over a gas burner - on a monster scale! I had a laugh!

    But that looks good.
    With your basket, there was a recent thread on SS pencil caddys used for a similar purposes - that seemed cheap and available :-)

    Matt

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    Pictures of keg roaster

    Here are some pictures of the keg BBQ which may help in my explanation of what I'll be doing.

    The motor will be replaced with a faster unit, I'll be looking for the upper end of 30-60 RPM I think. I have a friend who deals in electric motors and will probably try a few, he's in Sydney though and I'm Melbourne so it might take a little while.

    I plan to cut a hole on the left and right of the unit, a fan will be mounted on one side and the other will be the exhaust vent. I need to find some metal ducting to determine what sizes to cut first though.

    I'm not going to worry about fancy exit strategies at this stage and will just pull the basket out and manually dump, this is first of all "the first version"
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  23. #23
    Member themurphs's Avatar
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    Hi Brett,

    Man i was way off!
    Try a test run before cutting holes for the fan and extraction, see if your happy with the chaff in the bottom of the keg.
    Start off with small batches and see what you think.
    Even cutting a slot at the lowest point of the keg and collecting the chaff in a container might be enough.
    in my BBQ i have no extraction for the chaff but end up with a heap in the bottom of the BBQ. then after cooling i sift out the remainder, (i find this quiet peaceful!)

    For a basket idea check out this post.
    http://coffeesnobs.com.au/roasters/3...q-roaster.html

    Scroll half way down and have a look at the cutlery holder, quite a good idea from fg1972
    there is also a picture of my roasters opening on this page too. (hinged at the side).

    I would also look at mounting some sort of temperature gauge on the lid of the keg. it is what i have on the BBQ and does a good enough job.

    Hope this helps

    Glen

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    A few questions for building a new roasting machine

    Quote Originally Posted by themurphs View Post
    Man i was way off!
    Not at all mate, it helps us think differently and each idea can evolve. Having a look at your drum it may just be the right size I'm looking for too, though I'd be after one without ends but that would be a perfect start for me. You have a post what materials you used to make it?

    Quote Originally Posted by themurphs View Post
    Try a test run before cutting holes for the fan and extraction, see if your happy with the chaff in the bottom of the keg.
    Even cutting a slot at the lowest point of the keg and collecting the chaff in a container might be enough.
    You could be right, and I think that's a wise idea When I do cut holes I may try putting closable valves similar to a webber I think, might help me control airflow.

    Quote Originally Posted by themurphs View Post
    I would also look at mounting some sort of temperature gauge on the lid of the keg. it is what i have on the BBQ and does a good enough job.
    Definitely, I may mount something on the door as you suggest and on one of the sides if I manage to get the basket I'm after.

    I'll draw up the plan for what I'm after in a basket and post soon.

  25. #25
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    Quote Originally Posted by themurphs View Post
    My drum is 300 mm L X 120mm in diameter.
    I'm after a drum with pretty much the same width as that. I measured the full clearance space with plenty of breathing room and I'd need a 320 L x 120 radius (240 diameter).

    I'll be hunting for something suitable to start with It's surprising where people find the basis for their components, maybe I should start at a fish and tackle shop, I had a laugh.

  26. #26
    Super Moderator Javaphile's Avatar
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    As I recall some years back a user who was making their own (BBQ?) roaster ran across a perfectly sized waste bin made from SS mesh. Y'all might find just what you're looking for over there ----------------------> in Housewares.


    Java "Going up. 3rd floor....Hardware, Housewares, and other assorted roaster parts!" phile
    Toys! I must have new toys!!!

  27. #27
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    Behmor Coffee Roaster
    A waste bin, now that would be interesting.

    I live a block away from IKEA here in Springvale. I think I'll be hunting the bargain shops and IKEA this weekend for something "special"



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