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Post by lilypa on Aug 7, 2014 13:50:12 GMT -5
So Tim,
Have you wired your oven so that all four heating elements (the 2 upper and 2 lower) are on while you're roasting? Or is just one pair (either upper or lower) on during the roast? As John mentioned, that would cut your max roasting power in half to 750W, which might necessitate the need for longer roasts (>30 minutes).
Do you think with your current system, you could do a semi-decent roast in <=30 minutes?
Also...thank's for the homeroasters link. Based on their equation, and how much cocoa beans John mentioned you could load into the Behmor, that equation for cocoa beans in a Behmor (168 cubic inches) would be something like:
Roast weight (ounces) = Drum Volume (cubic inches)/3.5 - 4.2 (as in the divisor's range would be somewhere between 3.5 - 4.2).
Note that the Behmor's max power using just two quartz heating elements is specified as 1630W. Typical Behmor roast times are about 16 minutes plus or minus 2-3 minutes. So, maybe if your oven only uses 2 heating elements which can provide 750W, perhaps typical roast times could be about double the Behmor's (32 minutes plus or minus 4-6 minutes). Although, I really don't know much about power/electrical stuff and how that relates to roasting. Is my thinking off-base?
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Post by timwilde on Aug 7, 2014 16:17:15 GMT -5
No, I havent rewired anything more than just the fan/rotisserie function.
I have not looked into the heating elements at all. I may consider doing that at a later time, but in all honesty, I'm not in a huge hurry so the 1hour+ roasting times arent an issue for me. as I'm working with the Santha and only one Santha, so getting it into the santha faster isnt really going to help speed up the process any. As it is, with the drum I have, I believe I'm roasting more than the santha can handle of any of my recipies.
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Post by timwilde on Aug 7, 2014 18:40:28 GMT -5
I have taken a look at the oven's specs. It's a 1500W oven with 1500W Peak Power. That means each of the elements (of which there are 4) would be 750W. So, I can only ever utilize 1500W at any given time without rewiring.
That being said; That's not something to be taken lightly. I will need to check to see and validate that if I were to rewire this and take advantage of 3000W of power that I wont be melting the oven or it's contol electronics. There is virtually nothing but stamped sheet aluminum for insulation. That stamped aluminum separates the baking/cooking cavity and the electronic controls on the dials, as well as all of the electrical wiring. 1500W is a lot of heat, and I'm sure this was designed around that, but 3000W may be beyond the specs of everything involved here.
John/Ben, anything to add there? I know I'm new and still learning electronics, not sure if my concern is fully warranted or not.
Forgot to also add: the draw on a standard 110v socket. You'd need, absolutely, a separate 20A or greater circuit (with nothing else powered at the same time) to ensure the thing will stay on, and with the heat generated, there's a very real possibility that 3kw of heat would melt the aluminum. Might be above and beyond what is capable here, while maintaining a budget build.
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Post by lilypa on Aug 11, 2014 11:57:17 GMT -5
Hey Tim,
I think 1500W is plenty enough for the amount of cocoa beans you want to roast. I was concerned that you might only obtain 750W at one time. The Behmor coffee roaster has only 2 quartz heating elements that provide up to 1630W. Sounds like you could still do quicker roasts in your oven if needed, or wanted with 1500W.
I agree that you'd probably fry your unit trying to rewire it to use all four elements at once.
Thanks for letting us know your oven specs.
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Post by lyndon on Sept 1, 2014 14:04:29 GMT -5
Well, I have almost finished building my own one of these now, but I am wondering if the drum should be coated in some sort of food safe resin/paint for safety?
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Post by Ben on Sept 2, 2014 6:49:02 GMT -5
I wouldn't use a paint or a resin.
Apparently, most coffee drums are made with just regular mild/carbon steel--not even stainless. They season them by doing several extra dark roasts with an oily bean. You could probably do the same by just roasting some nibs.
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Post by lilypa on Sept 2, 2014 12:47:47 GMT -5
Hey All,
What is a good rotation speed for cocoa beans in a drum roaster (i.e. in rpm)?
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Post by lyndon on Sept 20, 2014 5:56:01 GMT -5
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Post by lyndon on Dec 27, 2014 12:43:58 GMT -5
Just on a side note, the most I can get into my drum is around 1.5kg, as I get closer to 2kg the motor is not strong enough to rotate it. I imagine at some point in the future I could simply swap out the motor with a better one though.
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Post by timwilde on Jan 27, 2015 15:14:21 GMT -5
I wanted to throw an update out there and mention some notes about roasting and roasting times. I've seen a few hemming and hawing about the times I initially quoted.
As far as I can tell, roasting time is dependent on roast size and roast profile. For my normal slow and low criollo roast, I can get 1lb in and out of the roaster in about 15-20 minutes. 2lbs ups that as there's more mass to warm up. For that initial slow and low roast it will take about 1 hour @ 4lb batch size.
That being said, different beans have different roasts and each of you will develop your own profile.
An aggressive profile (very hot, then scale back) I can get a 4lb batch out of the machine in 30 minutes with a 308F bean temp.
Medium profile (higher heat and scale back) I can still get about a 4lb batch out in about 40 minutes with about a 280F bean temp
A slow and low profile 4lb batch comes out at about 260F after about 50-65 minutes.
If you preheat the roaster/oven first, that can shave upwards of 10-15 minutes off total roast time as well.
It all boils down to what you're looking to do and how you wish to accomplish it. Thus far, I think it's a decent all-around small batch roaster. I think if you're super agressive with your roast profile and are willing to risk some over roasted beans in the batch, you can easily even get a 4lb roast out in about 20-25 minutes with an avg bean temp in the 280-300F range. I've tasted a few batches trying for a super aggressive roast that way and have yet to actually burn or otherwise waste a batch.
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gap
Apprentice
Posts: 390
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Post by gap on Jul 17, 2015 6:09:17 GMT -5
Hi - any update on this DIY model? Anyone else tried it?
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Post by timwilde on Sept 18, 2015 2:34:42 GMT -5
Hi gap, nothing to really update. I've been using it for about a year now and it's going beautifully. I have not seen a drop in performance or any finicky behavior as time wore on. I used it last year during my chocolate season doing about 3 batches per week from Dec-Mar. I need to rebuild the drum at some point, the screen material is starting to fray. But otherwise, the oven is just working. The last post I did in Jan was as complete an update as I can provide. I'm heading into the chocolate season once again, and I'm comfortable with relying on this roaster while stepping up production considerably.
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gap
Apprentice
Posts: 390
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Post by gap on Jul 14, 2016 19:13:23 GMT -5
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Post by isobel on Jul 15, 2016 4:11:24 GMT -5
Thanks Gap, that's exactly what I've been looking for but didn't know where to start searching!
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