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Building help on a 300 gram Drum roaster
Coffeeluke
Hello, I would like to build a Drum roaster that can roast a minimum of 300 grams. I am fairly new to this, I have been roasting on an air popper for quite some time and would like to make the switch to a drum roaster, but none of the ones on the market really meet my preferences. I am also fairly handy and enjoy building things myself. I have a friend who does steel work, so he will be doing that for me. I am planning on using a 5"Dx7"L perforated drum. I would like to keep the roaster as small as possible without affecting it's performance.

I currently have 2x 1K watt heating elements from an oven. I would like to keep the basic style of a commercial roaster, with the door release in front and a Trier. Any and all advice is greatly appreciated. Where do I start my plans? I have looked at many different threads around here but just can't figure out where to start.
 
John Despres
Welcome and this is a great first post and a great way to jump right in.

I'd suggest sketches of your ideal roaster with notes. Post them here and someone is bound to have an idea or suggestion. This could help carry your design forward and on to implementation.

Good luck.

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
 
JackH
Welcome Coffeeluke!

You might want to take a look at Allen's Easydrum roaster build for some ideas:

http://forum.home...ad_id=2488

I think he started with electric and ended up converting it to gas.
Edited by JackH on 08/29/2013 3:16 PM
---Jack

KKTO Roaster.
 
ginny
Hi:

thanks for joining us.

I would agree with Jack and take a look at Allen's drum or other roasters that members have built.

It would be helpful if you had some idea of design you could post for us to see where we may be able to help.

Sounds like you have some idea of what you want and there is no question that buying a store bought is not for you at this time.

Let's see some frame work and we will get you built...

beach
 
allenb
Hi Coffeeluke,

If you end up going in the direction of the Easydrum especially the single-ended shaft support concept be warned that the double bearing arrangement takes a little doing to be able to adjust the two bearings for drum alignment with the front plate. Otherwise it's pretty straight forward. Also, it's a lot less work to forgo the linear sliding front plate and just go with a traditional dump door. One thing nice about using the rear hung drum is having more real estate on the face for placing your trier and thermometers especially if you're using reverse pitch vanes in addition to the forward pitch ones. Your trier could go in the center where you'd traditionally mount your front bearing.

Be warned that with a perfed drum with large holes and the heat source underneath you have a tendency for burning chaff as it falls down onto the elements.

For a look at the first thread showing where the drum came from see:

http://forum.home...ad_id=2487

Saved me a lot of time fabbing a drum!

Advice on where to start? My own routine is to draw everything out on graph paper to make as many mistakes there first. Draw it from the top, side, bottom, front to know for sure what's going to bump into what before you start trying to fit all those pieces next to each other.

Leave at least 3/4" between drum and internal sheetmetal layer and at least 3/4" between internal and external layer. Don't use smaller than 1/4-20 size all thread or rod between rear plates and front plate especially if rear hung.

Leave at least 2" between rear of drum and internal rear plate for easy air movement from heater element area back around into rear of drum (if using a solid drum).

Please take a look at all examples of drum roasters in the drum forum before making up your mind on how you're going to build it. You'll find lots of clever design ideas from members builds!

Happy building!

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Coffeeluke
I was looking in to possibly bending my heating elements around the top of my drum, and having an inch and a half between the drum and the inner surface, leaving plenty of room for the elements. This would leave the option of having the chaff fall underneath.

If I were to bend the heating element around the bottom half of the drum, would it be possible to suck the chaff out where the beans come in and build a chaff collector near there on the outside of the roaster?

I am not quite sure how beans don't fall out of the front of the drum. Doesn't there have to be a gap between the front of the drum and the inside wall to prevent metal scraping? This may be a silly question, I just am not sure.

Thanks for all the help so far. I am going out of town this weekend but will be back at the drawing board on monday.

Also could you please explain the benefits of the radiant heat source inside of your easy drum?
 
allenb
Regardless of how your airflow ends up you will not prevent chaff particles from dropping out through the holes. How large are the holes in the drum you're considering? If they're small enough it shouldn't be an issue either way. If they're getting near 3/16" diameter then sizable pieces of chaff will drop out.

You want your electric elements as low as possible for keeping things efficient but don't need to be center bottom.

The gap between front of drum and front plate just has to be large enough so that when the drum is at max temp it doesn't rub. I keep around 1/32".

The radiant elements inside the easydrum were just to experiment with direct to bean radiant roasting which in the end was really no different than radiant to bean in a Behmor. Radiant to bean produces a very nice roast but can be a little tough to control due to the non-linear absorption of heat as the bean goes from light to darker.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Coffeeluke
Awesome thanks so much. I was originally planning on 5mm holes but I'm now thinking 3mm may be better? Should i just go solid drum? I was under the impression that perforated was better for smaller loads.
 
Dan
If have found that 5/32" is great, that's equivalent to 4mm.

hope this helps, Dan
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Coffeeluke
How do these look so far? very early drawings.
http://imgur.com/...
http://imgur.com/...
 
Dan
Looks good, to me. You can't go wrong using a traditional compenent layout.

Dan
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Coffeeluke
If the drum is mounted to the front and the back do I still need double bearings? How far do my heating elements need to be from my drum? If i go with 5/32'' holes will chaff fall through?
 
allenb
If you mount the drum front and rear you only need standard single row flange mount bearings.

There's not a critical minimum distance between tubular elements and the drum but for efficiency I would keep them closer to the drum than to the inner skin of the roaster.

Even with very small holes you'll have some smaller chaff bits and pieces fall through the holes and you'll need to periodically clean the area below the drum. A few small particles hitting the elements won't cause any problems from my experience. I'm not certain how large of a chaff flake will make it through 5/32" holes.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan

Quote

I'm not certain how large of a chaff flake will make it through 5/32" holes.


I'm pretty sure the largest ones will be... wait for it... 5/32" woohoo
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
allenb
My 1/2 lb drum roaster has 1/8" holes and due to the rubbing/tumbling action of the beans it allows larger than 1/8" chaff flakes to drop out of the drum.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan
I stand corrected. :)
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Coffeeluke
Hello, Things have been slightly delayed, but I think I am coming close to making my metal orders from my steel guy! I have my dimensions pretty much figured out, but the one thing i don't have is metal thicknesses. Any ideas on drum thicknesses, as well as thicknesses for the inner and outer walls? I will be using 1 inch insulation of kaowool on the sides. My plan for airflow is to put a large fan underneath my cooling tray, pulling air through the tray, up through heating elements, and then to the back of the drum. The air will exit where the beans go in. Any Ideas on what PID I will need? I am going to need some help with the electronics. All help is appreciated. Also, do i need an AC motor? Do I also need an AC fan?
 
allenb
Hi Luke, sounds like you're getting ready for the fabrication phase. It's always fun to see the individual parts start coming in and doing dry run assembly.

On drum wall thickness? For the size your building which I'm assuming will be roasting no more than a couple of lbs max, anywhere from 16 gauge up to 1/8" works great and allows steering tight turns in the profile. I really like the 16 gauge I'm using in the easydrum as it has just enough thermal mass to give the coffee an initial kick at the start of the roast but not so thick to make it hard to make the quick drop in rate of rise at first crack.

For inner wall, it doesn't need to be very thick as long as it isn't structural. If you go too thick you'll have to have a shop roll form it.

For outer, I'd go as thick as possible but where you can still bend by hand flexing.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Coffeeluke
I should also add that I would like to run the PID to a laptop, probably using tc4. The space for my fan is limited to 5inches tall by 9 inches wide by 7 inches length. I would like to keep my motor as small as possible, but it must be no taller than 4 inches, wider than 8 inches, and longer than 6 inches. Any Ideas?
 
Coffeeluke
anyone?
 
ginny
Hi:

you need to give folks time to get to you. many members are not on all of the time and do not know there is a new post if they do not watch it via email so hang on and be patient with us.

many others have no interest in building and only watch roast posts...


ginny


beach
 
Dan
What about a little shaded pole motor with 3-4" blade like this?

img0038.popscreencdn.com/146720079_shaded-pole-motor-oven-fanexternal-rotor-motormicro-.jpg
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Coffeeluke
Sorry about that ginny!

Dan; What would be the purpose of the blades on that motor?
 
Dan
LOL! You said you wanted a cooling fan!? I've seen larger fans on the same size and type of motor. Some are metal and as large as 5" in diameter.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Erichimedes
I found a motor exactly like the one Dan posted, with a larger fan on it, in the bottom of an old food dehydrator. Not sure if you're into thrift store scrounging at all, but it might be a start.

I also saw someone mount a little 4" squirrel cage on one of those motors in a different post. I liked that idea.
 
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