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allenb
OfflineAdmin
· 04/02/2020 4:50 AM
Morning Ed, I haven't done any green coffee hoarding yet but am hoping the supplies don't end up like the toilet paper isles!

snwcmpr
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· 03/31/2020 2:53 PM
Hey Ed. Thanks. roar

homeroaster
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· 03/31/2020 11:21 AM
Hey quarantined home roasters! I hope you have great coffee! If they have a run on coffee, I hope you're set with your great home roast! Find me on Facebook! Ed Needham

snwcmpr
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· 03/25/2020 11:49 AM
New Rochelle in the news. I think of you every time I hear it. ... Please stay safe.

allenb
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· 03/21/2020 7:36 AM
Good morning homeroasters morning Everyone is hopefully staying healthy through this. Hang in there and stay safe!

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Dereks 1-2Kg drum roaster build
dmccallum
Can I have some advise please on my vane config.

I've trimmed the drum just a little to 240mm dia x 250mm long, and have drafted 8 vanes (4 screw one way, 4 the other). Each set of 4 are 20mm high.

I can see that each vane end will have to be trimmed back by 5mm from each end of the drum to prevent beans getting caught in crevices.

One gap for me is the mention of a 25deg angle. Can someone elaborate on this - Is it the angle of the screw from the drum ends, or the angle between the vane surface and the drum wall?

Oooh and also, what direction do drum roasters typically rotate - anti-clockwise when viewing from front? Outer set of vanes in that case would then be oriented to drive the beans towards the front I imagine (reverse of how I have shown)?

Cheers
dmccallum attached the following images:
vanes4.jpg vanes3.jpg vanes2.jpg vanes1.jpg

Edited by dmccallum on 01/06/2016 7:59 AM
 
dmccallum
Where I've got to for the moment. Please do chip in with any feedback or advice.
dmccallum attached the following images:
2kg-concept-pr20160105.jpg 2kg-concept-pr20160105-2.jpg

Edited by dmccallum on 01/06/2016 10:16 AM
 
allenb

Quote

dmccallum wrote:

Can I have some advise please on my vane config.

I've trimmed the drum just a little to 240mm dia x 250mm long, and have drafted 8 vanes (4 screw one way, 4 the other). Each set of 4 are 20mm high.

I can see that each vane end will have to be trimmed back by 5mm from each end of the drum to prevent beans getting caught in crevices.

One gap for me is the mention of a 25deg angle. Can someone elaborate on this - Is it the angle of the screw from the drum ends, or the angle between the vane surface and the drum wall?

Oooh and also, what direction do drum roasters typically rotate - anti-clockwise when viewing from front? Outer set of vanes in that case would then be oriented to drive the beans towards the front I imagine (reverse of how I have shown)?

Cheers


I've found that going any less than 16 mm between front of roaster and front end of vanes will cause beans to cause a fairly severe thump when they line up and jam between metal parts. This can be more severe when opening the dump door and beans are jamming between vane front and edge of dump opening. No gap is necessary between vanes and rear of drum.

Clockwise/counter clockwise doesn't matter and I've seen commercial roasters use either one. Obviously, where you locate the trier and thermometer will be determined by which one you choose. The outer vanes are always used for pulling the beans out during dumping.

For vane angle calculation, drawing a straight line from front to rear on the drum wall would be the base of the angle.

For some recent discussion on this topic read a ways into this thread and you'll see some useful information.

http://homeroasters.org/php/forum/vie...post_56317

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
dmccallum
Thanks for that Allen.

Another query around cooling tray and its size.

If my drum size and volumes for intended 2Kg loads are,
Radius 120mm, Length 250mm and volume = 0.0113m3 or 11.3L

Then I've approximated the cooling tray at,
Radius 165mm, Height 100mm giving a volume of 0.00855m3 or 8.5L

I can't imagine this would be too far off the mark. Is there a general rule of thumb for sizing cooling tray relative to drum size and load? Appreciate the wider the tray the more the rate of cooling, I'm just trying to keep dimensions under control. I intend to have a dedicated blower on the tray.

Thanks for everyones input. I am leaping into this having only ever viewed an old Vittoria roaster some time ago. Apart from that I'm relying on google search and your input.

Cheers!
dmccallum attached the following image:
coolingtrayq.jpg
 
allenb
I don't know of a general rule of thumb but in most of my experience, I've never seen a commercial roaster cooling tray that a roasters full capacity produced a bean depth that came much over 1/2 the cooling tray's height. The swell of beans just in front of the sweep arm can be much higher than the non-moving beans.

You'll have to convert to metric units but 1 lb of roasted is around 70 cubic inches x 4.5 (2 kg) = 311 cu. in.

A 2" bed depth in a 13" diameter cooling tray (330 mm) is around 265 cu. in. so you may run into trouble if your sweep arm is tall enough to cause a big swell.

As far as rate of cooling? I can't see a tray of this size having any problem cooling 2 kg of beans in a pretty short time frame with even moderate air flow.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
dmccallum
So, I've increased the depth of the cooling tray to around 10L volume and started to add pipes back to the cyclone. A chap called Moshe over at Home-barista.com was kind enough to field a call and provide a number of photos of his San Fransican SF-1 cyclone in a disassembled state. Very helpful and filled some gaps for me.
The design of the SF-1 cyclone is very simple and will allow me to draw from both drum and cooling tray with one fan.

I have replicated the SF-1s dimensions and need to consider if a cylcone designed for a 0.5kg machine will work for 2kg. Any thoughts anyone? Just how much chaf do you expect to get from a 2kg roast?

I've put two 1 3/4" pipes to the cooling tray. Needed to do this to get either side of the burner which will sit in between. One of the pipes can be bent thus forming a 3-point anchor for the cooling tray.
Yet to sort out a manifold to get the two tray pipes into the 3" pipe inlet under the cyclone.

The SF-1 uses a 130CFM fan so figure this one http://www.electricmotorwarehouse.com...vOtKb.dpbs should suffice.
dmccallum attached the following images:
coolingtray20160114-2.jpg coolingtray20160114-1.jpg
 
dmccallum
Think I'm just about done with the 3D model now. It's easy to get a bit carried away and produce lovely pictures but it does help to flesh out as much as possible what will work, how and also to reduce the amount of fabrication you have to do yourself or re-engineering you might find yourself doing in the course of..

I've reconfigured the chain drive to include a shaft to the cooling tray although I haven't yet figured out the mechanics of a tray arm and connecting it up.
Venting will be controlled by the damper and flap shown.

So here's a bunch of pics. I've had a few comments from various people about what to consider and would welcome as much feedback as possible. Otherwise I'll start on 2D autocad and get some steel cut.
.
dmccallum attached the following images:
coolingventopen.jpg coolingventshut.jpg 2kg-concept-pr20160311-8.jpg 2kg-concept-pr20160311-7.jpg 2kg-concept-pr20160311-6.jpg 2kg-concept-pr20160311-5.jpg 2kg-concept-pr20160311-4.jpg 2kg-concept-pr20160311-3.jpg 2kg-concept-pr20160311-2.jpg 2kg-concept-pr20160311-1.jpg

Edited by dmccallum on 03/11/2016 7:50 AM
 
dmccallum
I meant to ask if someone could comment on my trier and TC config?

The drum rotates anti-clockwise and I've put a TC in the drum vent/hopper assy and one in the drum door.

Anything I'm missing?
 
hbboyd
Trier and TC placement look good mine are in similar places ( I have clockwise rotation though). I have to say that the trier size looks overkill to me and the small tub you have it resting in looks a little short, you might get beans flying out of it.
 
dmccallum

Quote

hbboyd wrote:

I have to say that the trier size looks overkill to me and the small tub you have it resting in looks a little short, you might get beans flying out of it.


Just the steer I was hoping for!
Thanks very much.
 
dmccallum
Have rejigged the trier for 50mm capture and the holder tube/tub 50mm also.

Does the action of the beans tend to move the trier around ? How's it normally secured ?
dmccallum attached the following image:
trier1.jpg
 
allenb

Quote

Does the action of the beans tend to move the trier around ? How's it normally secured ?


Yes, the beans do move/vibrate the trier and will tend to back it out if you don't mount it on a slight angle. The angle also prevents beans from finding their way through the trier hole and out into your cooling tray. I would do as Probat does and include a protruding "thumb" extension of metal extending out from the base of the trier to act as a pendulum to allow the trier to always end up rotating itself cup side down when you place it back in the hole.

My advice to anyone building a drum roaster is to take the time to put together a mock up see through front out of acrylic or lexan to get a real picture of bean movement/trajectory. Otherwise you're only able to make a good guess as to where the best spot is to capture beans in the trier and especially for best probe placement. Depending on rpm and vane size/placement, some roasters favor mounting the trier on the up-travel side and others the opposite side. Same goes for the probe. Mine sees the highest density of beans where you're showing it in your graphics. Locating the probe in a low density area can cause it to be affected by convection currents. Another tip is to make sure you don't locate the trier too close to the vanes. Leave at least 3/4" if not more between any part of the trier and vanes.

If you don't want to spend lots on a large piece of acrylic, use 1/4" mdf and cut out a large rectangle to mount a piece of acrylic in. Make the acrylic area large enough to see most of the bean action.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
dmccallum
Have completed more of the cooling-tray mechanism, although haven't detailed how I'll connect the drive shaft to the arms. Adjusted trier angles on basis of previous comment.

At this point I've created a nice pretty 3D and I've about done with it at this point. From here I can start drafting 2D patterns in order to get steel cut.

I have shared the file in the 3D Warehouse for anyone who wants to take a look or hack it around.
https://3dwarehouse.sketchup.com/mode...a838240576

Please do feedback if you see anything I appear not to have considered.
dmccallum attached the following image:
2kg-concept-pr20160323.jpg
 
hbboyd
Hey, something to note. I was looking though your design and noticed that where the bean chute enters the drum you have a decent sized flat spot where beans will end up sitting and getting all nasty. I have attached an image to help show the area.
hbboyd attached the following image:
flat_spot.jpg
 
dmccallum

Quote


Hey, something to note. I was looking though your design and noticed that where the bean chute enters the drum you have a decent sized flat spot where beans will end up sitting and getting all nasty. I have attached an image to help show the area.


Thanks - hadn't considered that. And yes, the hopper + front plates would be something like 8+mm.
 
hbboyd
Yea I had to weld in in a small plate on mine to prevent this from happening which was less than ideal. How goes the transition to 2d? Do you have a manufacturer you're working with?
 
dmccallum
I'll start with 2D shortly, just waiting for any further feedback.
It won't take as long as the 3D and will use Seimens SolidEdge 2D Drafting package (it's free & very capable).

I have a stainless manufacturer I've used before which I'll likely get to cut the steels, and I use a model engineer who likes to recoup the investment in his garage of fancy CNC kit by offering out machining services. He's an especially useful guy to have met - real craftsman who can do things that regular commercials just don't do or would charge the earth for. I also use a british company called Lamb Engineering who build custom motorcylces (bit like Orange County Motorcycles off the telly). Again, someone with specialized skills who are willing to do things at reasonable cost, not that anything in this build will be particularly challenging. I have pondered getting my own lathe but just haven't quite been able to justify it yet.

When someone suggested they were looking for plans it occurred to me it would be a good idea to stick as much as possible to stock materials. I can't imagine at this stage if you got steels cut from equivalent metric or imperial stock that it would cause any problems. The venting tube is standard 1 3/4" mild steel tube and from what I can tell it's cheap as chips to order this bent to your specification. There are a few bits you'll have to get fabricated if you can't do it yourself, but otherwise putting this together should be straightforward.

One thing I'll have to do is get to grips with MIG welding. I mainly do silver-braizing with propane but can see that MIG would be better for the sheet work.
Edited by dmccallum on 03/29/2016 4:55 AM
 
hbboyd
Nice, sounds like you have it pretty sorted which is awesome.

Two additional things to note from your design:

1) I would incorporate some kind of chute/guard to keep the beans coming out of the roaster headed into the cooling tray, you'd be surprised the angle some will come shooting out at.

2) The hopper for your beans should be a more normal cone or pyramid for ease of fabrication. The shape you have right now is pretty odd shaped.
 
dmccallum

Quote

hbboyd wrote:

1) I would incorporate some kind of chute/guard to keep the beans coming out of the roaster headed into the cooling tray, you'd be surprised the angle some will come shooting out at.

2) The hopper for your beans should be a more normal cone or pyramid for ease of fabrication. The shape you have right now is pretty odd shaped.


Oh dang! I forgot to put the chute back in. Get onto that shortly

As for the hopper, yes it might seem a bit fanciful and will depend on how good I get at MIG welding. It has however been sized to accommodate a full 2kg load of beans and it keeps things within the outer dimensions I had in mind.
 
dmccallum
An idea I had from something I picked up in Scott Raos book where he talks about his preference for double-drums and talk here about installing a baffle.

Tell me if I'm getting carried away but this would be easy to implement with a few lengths of 3x10mm flat and 1mm sheet steel.
dmccallum attached the following images:
doubledrum_poss3.jpg doubledrum_poss2.jpg doubledrum_poss1.jpg

Edited by dmccallum on 03/31/2016 8:17 AM
 
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