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Cyclops - my 1kg drum build
pjvdl
Top  #51 Print Post
Posted on 10/26/2020 1:59 AM

Quote

allenb wrote:
So, does the air path go from an opening at the rear and blow across the coils towards the front of the roaster and then work it's obvious path around and back to the drum openings? This would be optimum.


Exactly. In the photo, you can just see the opening at the back of the element (partially obscured from view by one of the mica supports)

Out of interest, I am using a fan for push air through, rather than sucking from the cyclone. Seems to be quite effective and I don't need to worry about the fan having to deal with hot air.
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
allenb
Top  #52 Print Post
Posted on 10/26/2020 9:10 AM
The reason most drum roasters are designed with pull through the drum versus push is due to the difficulty of sealing all possible alternate path openings that the pushing source could send the air through which, depending on how many gaps were left during construction could allow a good % of the total fan output to end up bypassing the intended path rather than be strictly routed past heat source and straight to the rear end of the drum and through the drum and out. By pulling at the funnel, there is much less chance of large variations in total cfm across the coffee in the drum. As long as the air from the fan isn't able to make a quick turn up and into the drum's rear perf plate, which would be allowing cool ambient air to be flowing across the beans and subsequently cooling the beans while the drum surface is heating them, then pushing is fine and can be just as effective. OTOH, even a pull design can end up with this problem if the air entry point doesn't allow directing the air across the heat source prior to entering the drum.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
pjvdl
Top  #53 Print Post
Posted on 10/26/2020 5:54 PM

Quote

allenb wrote:

The reason most drum roasters are designed with pull through the drum versus push is due to the difficulty of sealing all possible alternate path openings that the pushing source could send the air through which, depending on how many gaps were left during construction could allow a good % of the total fan output to end up bypassing the intended path rather than be strictly routed past heat source and straight to the rear end of the drum and through the drum and out. By pulling at the funnel, there is much less chance of large variations in total cfm across the coffee in the drum. As long as the air from the fan isn't able to make a quick turn up and into the drum's rear perf plate, which would be allowing cool ambient air to be flowing across the beans and subsequently cooling the beans while the drum surface is heating them, then pushing is fine and can be just as effective. OTOH, even a pull design can end up with this problem if the air entry point doesn't allow directing the air across the heat source prior to entering the drum.


This is an interesting point, although I think another advantage of using a push method with a DIY build is that it is more obvious where air is leaking, because you can actually feel it being pushed through the gaps. My experience is that sucked air is more difficult to perceive by hand. During my build, I could easily feel where air was following an undesirable path, because I could feel it by hand - particularly if I turned the heater on to heat the air prior. I found a number of gaps using this method, which allowed me to modify my design along the way.

I have been left with a couple of tiny gaps between SS sheets that are bolted together, but expand (and therefore move slightly) when heated. I haven't worried about these yet, but if they become a problem, I plan to create some gaskets with high temperature gasket silicone.

The other reason I decided on a push method was more of an asthetic one. If I went with a pull method, I would have needed to mount the fan on the top of the cyclone, which I personally felt wouldn't look as good. Certainly secondary, but was minor consideration smile
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
renatoa
Top  #54 Print Post
Posted on 10/27/2020 3:20 AM
Don't forget the air temperature in both cases... pull = hot air, more expensive and quicker wear fan.
 
allenb
Top  #55 Print Post
Posted on 10/27/2020 7:13 AM

Quote

The reason most drum roasters are designed with pull through the drum versus push is due to the difficulty of sealing all possible alternate path openings that the pushing source could send the air through...


I failed to qualify this statement. This obviously only relates to electrically heated roasters or indirectly heated gas fired roasters utilizing a heat exchanger.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
pjvdl
Top  #56 Print Post
Posted on 10/27/2020 11:29 PM
Ok. So i have spent the last couple of days running the machine with its new heater through its paces. I have now completed a number of roasts:

500g x 2
700g x 1
1000g x 2

and am starting to get a feel for the machine with my new improved heater. Observations:

- Seems to have plenty of power for 1kg
- copes well with 500g as well, although need to turn the power down, otherwise I am getting to FC in under 5 minutes
- I am only using 10 - 20% fan through most of the roast, so should be a lower percentage of the heat through convection, with most through conduction/indirect IR

I can't say I've noticed much difference in terms of flavour yet, but I am certainly no cupping expert, and my tests to date are by no means controlled! Time will tell as I better understand the nuances of the machine I think.

I have also started playing with PID control (Artisan + Arduino + TC4+), with only limited success tuning the control loop so far. I need to get my head around this through more trial and error, but the slow response time of the machine makes it difficult to create a control loop that is responsive, but doesn't oscillate. I started with the default values in Artisan, but these were terrible for my machine, which has a response time of around 30 seconds (measured from time when the ET peaks to the time when BT peaks). Anyway, more time is needed on this ...
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
pjvdl
Top  #57 Print Post
Posted on 04/27/2021 6:13 AM
Well. It's been a few months since I last posted. Life has been busy, however I have been busy using my roaster with good success. That is not to say there haven't been some learnings along the way. And I am struggling with a niggling electronic issue that has me baffled (but more on that later).

Firstly though, I am having good success roasting batches up to 1kg. In fact I have overheated a few and had them hitting 1st crack in under 6 minutes Onot ideal I think), so plenty of power in reserve. Airflow is also good (subject to my comments below), with minimal air (10% power) throughout most of the roast, only increasing to remove chaff towards the end.

Learnings:

- Allen's observation that most electric roasters use a pull fan instead of a push fan because they are difficult to seal has been borne out. This is something that I failed to consider early on. I am in the process of converting to an AC sirrocco fan that I picked up on Aliexpress - needs a few hours though because I will need to change my arduino configuration. Watch this space.
- PID control on a drum roaster with a large heat mass has largely been a bust for me. The lag between the time the PID makes a control adjustment and the time I see a appreciable movement in output temperature is upward of a minute. This lack of responsiveness makes PID control difficult me thinks. Anyway, something that I will perservere with this a little more when I have some more time
- PID control aside, I am finding that I can make a few simple, well timed changes to the heat at key points in the roast to achieve roasting profiles that are repeatable and seem good to me

This brings me to the nagging electronics issue. I keep blowing the MCP3424 ADC chips that take the inputs from K-type thermocouples. Rathing than posting details here, I will post another dedicated post on this when I get a moment, as I am keen to tap the collective wisdom of this group - I am out of ideas!

Anyway, thought you might all appreciate an update and some insights that I have gained over the last few months.

On balance, this build has been far more challenging than I originially anticipated, but also incredibly rewarding. And family and friends are all loving the end product!

This is certainly not the end of the journey, but thank you all to your valued input so far. I doubt I would have got this far without it.
Edited by pjvdl on 04/27/2021 7:10 PM
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
renatoa
Top  #58 Print Post
Posted on 04/28/2021 3:07 AM
Regarding PID, some experiments to find step response (open loop) behaviour should give you valuable hints how to control your machine without PID.
 
pjvdl
Top  #59 Print Post
Posted on 06/23/2021 3:10 AM

Quote

renatoa wrote:

Regarding PID, some experiments to find step response (open loop) behaviour should give you valuable hints how to control your machine without PID.


Thanks. I ran some simple step temperature change tests a while back, but this is still on my to do list! Will post back here once I have tested further.
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
pjvdl
Top  #60 Print Post
Posted on 06/23/2021 3:20 AM
Well. I haven't had much time to spend on this rc recently, but I have received some replacement parts and a new furnace sirocco style fan. This required that I rewire much of the system and reprogram the TC4+, so I also took the opportunity to review the wiring based on feedback from Allen, renatoa and others on this forum.

The upshot of this exercise is that rewiring also fixed the problem with the MCP3424. I never found a definitive problem with the wiring, but I suspect that there was an undiagnosed short somewhere.

Anyway, the fan is also much quiter and sucking the air from the drum is a definite improvement in containing chaff. The only slight issue I have now is that it does not seem quite as efficient in separating the chaff from the beans - I think because the CFM and pressure is not as high as the previous. Some minor tweeking will be needed here.

All in all though, I'm pretty happy with the end product.

Thanks again for all the help I have received on this forum!
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
pjvdl
Top  #61 Print Post
Posted on 04/09/2022 7:25 PM
Hi all. I have been happily roasting since my last post; getting used to how the drum roaster performs. In general, I've been very happy with its performance. It will happily roast 1kg batches.

I am having a bit of an issue with the drum bearings though. I have a 12mm drum shaft and an using FL001 (flange) pillow bearings, which do the job, but I am using standard temperature bearings, which do not cope with the heat.

I am struggling to find anything suitable for higher temperatures. The best I can find is something like https://www.bocabearings.com/products/skfl001-12mm-21409, which is rated to 160C. The internal roasting chamber is getting to around 350C and the drum is getting to around 250C, so although the bearings are mounted externally, I'm still concerned 160C is not high enough.

Can anyone suggest a supplier of high temp pillow flange bearings for a 12mm shaft who would ship to Austraila?
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
UmMerkur
Top  #62 Print Post
Posted on 04/11/2022 2:01 PM

Quote

pjvdl wrote:

Hi all. I have been happily roasting since my last post; getting used to how the drum roaster performs. In general, I've been very happy with its performance. It will happily roast 1kg batches.

I am having a bit of an issue with the drum bearings though. I have a 12mm drum shaft and an using FL001 (flange) pillow bearings, which do the job, but I am using standard temperature bearings, which do not cope with the heat.

I am struggling to find anything suitable for higher temperatures. The best I can find is something like https://www.bocabearings.com/products/skfl001-12mm-21409, which is rated to 160C. The internal roasting chamber is getting to around 350C and the drum is getting to around 250C, so although the bearings are mounted externally, I'm still concerned 160C is not high enough.

Can anyone suggest a supplier of high temp pillow flange bearings for a 12mm shaft who would ship to Austraila?


I had the same struggle of finding a high-temp flange mounted bearing, so I decided to just mount the bearing on 1" standoffs to keep it away from the heat. If you have the extra length in your shaft you may think about that. I've attached an image of my CAD model, should be able to see what I'm talking about.
I'm a little worried about the door hinge bearings, but those are much lower duty so maybe it will be okay?
UmMerkur attached the following image:
03-07-2022_fullview_resized_1.jpg
Behmor 1600+, Fresh Roast Plus 8, Poppery II; Lelit Bianca V2, Eureka Mignon Specialita', V60, Breville SGP
 
allenb
Top  #63 Print Post
Posted on 04/11/2022 2:29 PM
The most I've heard of anyone doing, and that was due to grease separating and drooling, is go to high temp grease instead of standard. I know of no reason to look for any exotic bearings for high temp especially with the remedies just mentioned (space them away from the front plate a tad).

Paul, what are your bearings doing causing you to replace them?
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
pjvdl
Top  #64 Print Post
Posted on 04/11/2022 10:00 PM

Quote

allenb wrote:

The most I've heard of anyone doing, and that was due to grease separating and drooling, is go to high temp grease instead of standard. I know of no reason to look for any exotic bearings for high temp especially with the remedies just mentioned (space them away from the front plate a tad).

Paul, what are your bearings doing causing you to replace them?


My front bearing completely disintegrated; caused by the bearing covers becoming heat affected and the lubricant (greese) breaking down. To be fair, these were relatively inexpensive bearings, so I think the covers were a cheap plastic.

I was already thinking about separating the bearing from the heat as per UmMerkur's suggestion, so I think I will probably go with a higher quality SS bearing as I listed in my previous and separate it slightly from the drum face. The existing shaft has enough slack that I should be able to get a gap of 5 - 6mm. An air gap even this small should be enough that 160C rating will be sufficient.
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
pjvdl
Top  #65 Print Post
Posted on 04/11/2022 10:01 PM

Quote

UmMerkur wrote:

Quote

pjvdl wrote:

Hi all. I have been happily roasting since my last post; getting used to how the drum roaster performs. In general, I've been very happy with its performance. It will happily roast 1kg batches.

I am having a bit of an issue with the drum bearings though. I have a 12mm drum shaft and an using FL001 (flange) pillow bearings, which do the job, but I am using standard temperature bearings, which do not cope with the heat.

I am struggling to find anything suitable for higher temperatures. The best I can find is something like https://www.bocabearings.com/products/skfl001-12mm-21409, which is rated to 160C. The internal roasting chamber is getting to around 350C and the drum is getting to around 250C, so although the bearings are mounted externally, I'm still concerned 160C is not high enough.

Can anyone suggest a supplier of high temp pillow flange bearings for a 12mm shaft who would ship to Austraila?


I had the same struggle of finding a high-temp flange mounted bearing, so I decided to just mount the bearing on 1" standoffs to keep it away from the heat. If you have the extra length in your shaft you may think about that. I've attached an image of my CAD model, should be able to see what I'm talking about.
I'm a little worried about the door hinge bearings, but those are much lower duty so maybe it will be okay?


Thanks for the suggestion regarding the separation. I have been running my roaster for over a year with a similar door hinge setup and I haven't had any issues on that front, so you should be okay with yours. The photo below shows after a year's work (with a replacement main bearing which I had spare).
pjvdl attached the following image:
20220412_123233.jpg
Edited by pjvdl on 04/11/2022 10:07 PM
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
renatoa
Top  #66 Print Post
Posted on 04/12/2022 1:15 AM
What about using a custom made "bong", as those used by Pavoni users, to insulate the group from the boiler... ThumbsUp
 
pjvdl
Top  #67 Print Post
Posted on 04/16/2022 6:31 AM

Quote

renatoa wrote:

What about using a custom made "bong", as those used by Pavoni users, to insulate the group from the boiler... ThumbsUp


Was thinking about this as well. Thinking a simple silicone barrier, insulating the bearings from the heat of the chamber.
-- Paul

ECM Rocket espresso
Eureka Mignon grinder
500g BBQ rotisserie roaster
1kg drum roaster
 
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