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Homeroasters.org » BUILDING A ROASTER » Drum Roasters
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Dereks 1-2Kg drum roaster build
BobbyS
When you open the slide on the hopper, what keeps some of the beans from going out the exhaust on top?
 
dmccallum
The tube the beans drop through is about 15-20mm away from the horizontal draw tube so I'm not anticipating losing any as you'd have the damper closed when dropping.
That's the theory..
 
dmccallum
Have made some progress on the cyclone while I wait for other parts to be machined.
I created some templates for notching the incoming draw pipe and matching hole in the cylinder wall.
dmccallum attached the following images:
20171229_173926.jpg 20171229_172850.jpg 20171229_172759.jpg 20171229_162423.jpg 20180101_151402.jpg
 
dmccallum
I'm a beginner TIG welder and while I've had some one-on-one tuition there's still a fair bit to learn. Stainless steel warps terribly when heated and while I did a weld on the inside to attach the draw pipe and things were ok, I followed it up with a TIG braze on the outside with siliconbronze and applied too much heat. Shouldn't have done that - it was only for cosmetic reasons.
It can be corrected though by fitting the top ring to hold it true and I have had to get this part cut again in 3mm to cope with it. I have added a couple of additional bottom plates to the cutting files for the purpose of holding the cylinder to a true round during the welding process.

The cylinder wasn't entirely a true round when it came from the shop, but a beefed up 3mm top and bottom plate fixes any minor defects. Note to self in future would be to ask your fabricator what their capability is here. I'll be down to whether their slip-roller handles the ends of the material. I can't complain though about what they've produced as it can be handled.
dmccallum attached the following images:
20180104_230709.jpg 20180103_152631.jpg 20180103_152623.jpg 20180103_111040.jpg
 
dmccallum
Machined parts arrived and I've played a bit with fitting up.
dmccallum attached the following images:
20180104_230854.jpg 20180104_231042.jpg 20180104_231028.jpg 20180104_230956.jpg 20180104_230811.jpg 20180104_230655.jpg
 
dmccallum
Machined parts back from my usual bloke. The drive shaft is 15mm in the middle with the ends turned down to 12mm to fit the bearing ends and a keyway milled for the chain-ring.
dmccallum attached the following image:
20180104_120039.jpg
 
allenb
Hey Derek,
After seeing your design and fabrication prowess, I'm ashamed to look at my drum roaster!

Can't wait to see this all come together into a complete roaster!

BTW, whats the procedure for getting the spokes into the holes of the drum? Back out each spoke from the hub once in place and backup nut on the threaded end at the hub? This would make it adjustable for centering the works.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
dmccallum
allenb wrote:
BTW, whats the procedure for getting the spokes into the holes of the drum? Back out each spoke from the hub once in place and backup nut on the threaded end at the hub? This would make it adjustable for centering the works.


Hi Allen
That's the idea. The rear collar on the shaft will also allow you to fasten the drums perforated back plate once it's running true.

Have to approach getting the vanes mounted inside the drum next which will be fiddly.
dmccallum attached the following image:
20180106_100247.jpg
 
allenb
If welding, be sure to utilize magnets where possible for holding in place.

Be sure to leave an adequate gap between front end of vanes and front plate. I'd go no less than 3/4" and for the size roaster you're building, I'd go for 1".

Are you going to attach the return vanes to the forward vanes or attach to the shaft?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
dmccallum
allenb wrote:
Be sure to leave an adequate gap between front end of vanes and front plate. I'd go no less than 3/4" and for the size roaster you're building, I'd go for 1".

Are you going to attach the return vanes to the forward vanes or attach to the shaft?


Thx for that. I think i'd gone for about 15mm back from front plate going on previous threads - I'll bump it up to 20mm.

The return vanes will sit on top of the forward vanes. I have some pegs to put in place on the drum which both sets will be welded to.
 
dmccallum
I started putting my vanes together but decided it was going to look like a pigs ear,

i.imgur.com/M5yKaBG.jpg

i.imgur.com/3ZqbuTE.jpg

These did fit well inside the drum but not happy, so went back to the drawing board with sketchup and redesigned them with a view to making it a bit tidier not to mention easier to fit up and weld. Here's what came back from the cutting shop in 2mm stainless.

i.imgur.com/UA4JXdf.jpg

Once inside the drum,

i.imgur.com/PSQigTG.jpg

i.imgur.com/7Y8WjZ9.jpg

i.imgur.com/IGJvILk.jpg

A bit of progress also on the cyclone. I upgraded the cyclones top and bottom plates to 3mm. This helps to bring and keep the tube to a true round and also provides something to cut a thread into to secure it to the top and bottom assemblies.

i.imgur.com/lSJpdfH.jpg

Cooling tray draw tube with Thien baffle attached. Just about ready to mount inside the cyclone.

i.imgur.com/M7cbBRn.jpg

i.imgur.com/YRdOKBN.jpg

i.imgur.com/EHLbfQU.jpg
Edited by dmccallum on 01-29-2018 05:08
 
dmccallum
Got the revised vanes welded up. Much better experience and it fits the drum very well.

I had a thought to weld some tabs onto the outside vanes to enable the vane assembly to be removable. For what purpose I'm not sure, but it's direction I've headed.

i.imgur.com/4PZQqOa.jpg

i.imgur.com/pztfx51.jpg

i.imgur.com/PcxP8Yt.jpg

i.imgur.com/65n2oIX.jpg
Edited by dmccallum on 01-30-2018 02:17
 
dmccallum
Got the drum more or less finished. Just need to fit the second skin and that bit'll be done. Runs really well in the chassis.
i.imgur.com/CebzAvg.jpg

i.imgur.com/FP5Kiux.jpg

i.imgur.com/GATRAnN.jpg

i.imgur.com/kvlH9Eb.jpg
Edited by dmccallum on 02-11-2018 23:51
 
BobbyS
That is looking great! It is coming along nicely!
 
renatoa
What is/was the final choice for the motor?
Asking because for me a 28W AC, 60 RPM, 1N.m, can't turn a 3kg drum with 1kg greens inside...
 
dmccallum
renatoa wrote:

What is/was the final choice for the motor?
Asking because for me a 28W AC, 60 RPM, 1N.m, can't turn a 3kg drum with 1kg greens inside...


Well that's interesting. For my drum at approx 7kg, 250mm OD and 250mm in length on a 12mm shaft that is mounted either side on housed bearings, the 15W geared motor in the following link is what was reccomended.
http://www.gapp.c...otors.html

I passed the dimensions of my drum to get a spec and this is what was fed back to me.

"Even with the increased load then you will only need 0.88Nm.

Although probably in reality you need far less as I sized this as the load being on the periphery of the drum and a co-efficient of the bearing as 0.1.

In reality the load is within the drum and the bearing friction co-efficient will be far less.

If motor/gearbox size is an issue then the 6W should be OK but if not then I would use the 15W solution personally. The extra torque available will mean a better service life from the gearbox anyway.
"


I haven't purchased the motor yet but was probably going to get to that shortly.
Could you share some more detail of what you have and are experiencing ?
Edited by dmccallum on 04-10-2018 11:03
 
renatoa
This could explain... my motor has only 0.2Nm at start and max 0.5Nm torque.
Power seems to be just a label... chinese label ;) instead the labelled 28 W I measured 64 mA = 15W...
Also, my drum is not on a shaft, is empty inside, for designing purposes - think to Gene ;) So torque to move it is probably different...
It is supported by two lateral rows of bearing/teflon rolls and side driven by a belt.
Will try a first palliative, by changing the drive ratio, thus increasing torque, actual 65 rpm seems way too much when I am looking how beans are thrown by all the walls inside... 20 RPM of Dieckmann RoestMeister looks about right for me.
 
alexcampbell
Beautiful work.
 
Moonshine
Great job on the vanes! Looks like something that could be in the sculpture section of an art gallery, and scaled up, it could be a rotor assembly for a vertical wind turbine.
 
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