Homeroasters - Home Roasting Coffee Community » BUILDING A ROASTER » Drum Roasters
Who is here? 1 guest(s)
 Print Thread
First drum roaster project - ideas for drums?
hallgeirl
Top  #1 Print Post
Posted on 07/16/2020 3:38 PM
Hi all,
First time poster here, and love reading all the experiences in this forum. There's really a lot of great projects here to look up to. Kudos to all.

So I've been roasting on my heat gun + bread machine roaster for a while now, and although it works great and I get some really good roasts from it, I am longing for an actual drum roaster. This is both because I want to build something new, being able to handle a bit larger batches, and to experiment with other roast parameters like air flow and charge temperature. I'm aiming to do 1.2kg batches of greens, that's about twice the batch size I have currently.

In my head I figured it was a good idea to start with finding a drum, since that kind of will define the scale of the rest of the roaster. One goal of the project is also to keep the cost down, thus do most of the work myself, and use existing parts when possible so I don't need to have them made by someone else.

I'm reading a lot of recommendations for no less than 3mm wall thickness. Also from what I've read, the conversion rate for bean capacity in kg to drum volume in liters is about 1/6 (so a 1kg roaster would need a drum volume of 7.2 liters). Given this, I have some alternatives that may or may not work:
* I can get a hold of a 2mm x 200mm x 250mm steel pipe meant for connecting wood stoves to a chimney (200mm is the outer diameter) giving a volume of 7.7 liters. However, it's only 2mm thick.
* I got a fire extinguisher ready for retirement (I read someone used this in one of their builds on this forum). However, uncertain about the wall thickness - probably below 2mm. Also, the OD is around 150mm - that's a bit on the low side.
* I might be able to find someone to make a appropriately sized pipe needed (e.g. 3mm x 220mm x 220mm) but I suspect it wouldn't be cheap...

I'm really looking for outside insight here from those more experienced in this game than me. Some questions (feel free to answer also those I'm not asking, if I've missed some important questions):
1. Am I worrying about the right things (e.g. drum wall thickness - how important is it?)? Would the first alternative be just fine even with "just" 2mm walls?
2. Is there other good alternatives for drums for a DYI roaster?
3. One thing is the drum upper capacity, but what about the minimum load - what factors determine what the minimum load for a drum is? If I e.g. find an alternative that is 250x250mm (which should take 2kg), can that be used to roast e.g. 500g? Or should the load be closer to the max capacity?
Edited by hallgeirl on 07/16/2020 3:46 PM
 
oldgrumpus
Top  #2 Print Post
Posted on 07/16/2020 5:41 PM
My roaster is 1.5 kg capacity and I used a piece of water-well pipe. It's about 300mm in diameter but a bit thicker. I used a lathe to thin it down. I might suggest using an old propane bottle such as this:
oldgrumpus attached the following image:
propane_bottle_1.jpg
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
pjvdl
Top  #3 Print Post
Posted on 07/17/2020 1:07 AM

Quote

hallgeirl wrote:
* I got a fire extinguisher ready for retirement (I read someone used this in one of their builds on this forum). However, uncertain about the wall thickness - probably below 2mm. Also, the OD is around 150mm - that's a bit on the low side.


I'm using a re-purposed 9kg fire extinguisher. OD is 180mm and wall thickness is around 1.7mm. You will see from my other thread that I am still working through heating issues, so can't comment yet on whether this thickness will work.
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
hallgeirl
Top  #4 Print Post
Posted on 07/17/2020 2:27 AM

Quote

oldgrumpus wrote:

My roaster is 1.5 kg capacity and I used a piece of water-well pipe. It's about 300mm in diameter but a bit thicker. I used a lathe to thin it down. I might suggest using an old propane bottle such as this:


That's interesting. I don't have access to a lathe unfortunately so if water well pipes usually are very thick walled, I guess that's probably not an option for me.
Do you know what wall thickness those propane bottles usually have? I think I can get one of those used.

Quote

pjvdl wrote:

Quote

hallgeirl wrote:
* I got a fire extinguisher ready for retirement (I read someone used this in one of their builds on this forum). However, uncertain about the wall thickness - probably below 2mm. Also, the OD is around 150mm - that's a bit on the low side.


I'm using a re-purposed 9kg fire extinguisher. OD is 180mm and wall thickness is around 1.7mm. You will see from my other thread that I am still working through heating issues, so can't comment yet on whether this thickness will work.


Nice - I'll definitely check out your thread. This is quite similar to my option #1 (using a chimney pipe segment). So if yours work, then I think that chimney pipe would work as well.
 
oldgrumpus
Top  #5 Print Post
Posted on 08/14/2020 9:56 PM
Propane bottles are not very thick. I'm guessing they are about 2mm.
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
JackH
Top  #6 Print Post
Posted on 08/15/2020 3:49 AM
People have used the larger silver fire extinguishers for roasters.

I would avoid using galvanized metals.
---Jack

KKTO Roaster.
 
DrHenley
Top  #7 Print Post
Posted on 08/15/2020 10:45 AM

Quote


I would avoid using galvanized metals.

Like the plague! LOL
--------------------------------------------------------------------------------
AeroPress, Capresso On The Go single cup drip, Moka Pot
DIY Gas Fired perforated drum using TermoPro meat probe as bean probe (very accurate), Aillio Bullet R1 V2
A morning without coffee is like a marriage without a honeymoon.
 
Jump to Forum: