2kg Electric roaster

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
MM1
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Postby MM1 » Dec 18, 2016, 2:41 pm

I've been roasting on my 2kg electric roaster for about 3 months and have nothing but issues with it. When I purchased the roaster gas wasn't an option but now it is and I'm thinking about modifying the roaster. The main issue that I have is the lag time of the heating elements. They have a response time of about 1.5 minutes so I'm sticking using the airflow to control my RoR. The machine also recently had a solid state relay get stuck and before that it was burning up bearings before I made some modifications. The machine has a perforated drum so I was thinking about using IR burners or using a heat shield with black pipe burners to help heat dissipate and not scorch the beans. I guess what I'm looking for is some input on a burner setup for a perforated drum or ideas to improve the heating elements. It is currently using 5 800 watt tubular elements.

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drgary
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Postby drgary » Dec 19, 2016, 12:25 am

If this helps I have a North 1 Kg roaster and the only one of its kind with a perforated drum. The gas jets are located as usual for the solid drum version. No problem. It helps that the drum rotation speed can be adjusted so beans don't spend too much time over a hot drum or flame. Bella Taiwan gas roasters can also be equipped with a perforated drum. So if you look at the specs for a gas drum roaster handling 2 Kg, the number of the gas jets and their distance from the drum should be a good guideline.
Gary
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keno
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Postby keno » Dec 19, 2016, 1:04 am

+1 to what DrGary said.

I think the IR burners might be a good idea as they are a little more gentle than a direct flame burner which may make the IR burners preferable with a perforated drum. Many Huky roasters use a perforated drum and that roaster is supplied with an IR propane stove.

Who is the manufacturer and have you tried contacting them about a conversion kit?

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drgary
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Postby drgary » Dec 19, 2016, 1:26 am

keno wrote:Who is the manufacturer and have you tried contacting them about a conversion kit?


I agree that it's probably worth asking the vendor for a solution. I appreciate that the OP has used discretion in not naming the manufacturer. We ask people not to air vendor complaints but to try instead to work things out directly with the vendor. This is covered here:

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Gary
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MM1
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Postby MM1 » Dec 19, 2016, 10:17 am

The machine is a white label roaster I imported from China. It had favorable reviews that stated it was very well built for the price. Also, the bearings and motor are Japanese and the thermocouples are German. None of that really matters since the engineering and understanding of how a coffee roaster should function were severely neglected. I am going to send them an email and ask about a gas conversion kit. They have yet to reply to my email about the bad bearings and failed SSR so I'm not sure if they will answer but it's worth a shot.

MM1
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Postby MM1 » Jan 04, 2017, 1:43 pm

I have been doing some experimenting with my roaster before I decide to modify it.

First, it's obvious that the manufacturer just took a gas roaster and put heating elements in it. The doors on the side of the roaster that open to access the elements have the same size openings as their gas model. My first idea was to use space heaters to blow towards the roaster to reduce the deltaT across the elements...this didn't do anything.

Next, I covered one side with foil and added foil wrapped bricks to the inside to create a better thermal envelope. On the other side I only used a half brick and put a space heater to blow hot air in. This has allowed me to control the roaster better than before but still needs to be improved upon. I'm looking at adding VFD's for the exhaust fan and the drum speed. I would also like to see the inside of a coffee tech solar roaster to use as a comparison.

Séb
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Postby Séb » Jan 04, 2017, 2:16 pm

MM1 wrote: I would also like to see the inside of a coffee tech solar roaster to use as a comparison.

I have one, so just send me an email to tell me what exactly you would like to see in thoses pictures and i will send whatever you want. I love my Solar roaster btw, never had a single problem with it. Contact me by email please: info@lecafecrema.com

Wish you good luck with theses mods, hope you can improve the design of your roaster!

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summer
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Postby summer » Jan 04, 2017, 2:39 pm

I might also be able to help with pics/info of Solar. :D

MM1
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Postby MM1 » Jan 11, 2017, 1:34 pm

The pics of the coffee tech solar roaster were a big help. I am planning on buying the same Delta vfd that is on the FZ-94 but I haven't narrowed down a blower yet. I have been looking at a few daytons that are 3 phase and high temperature. My current exhaust blower is 95cfm but the next one will be 200 cfm. While I'm making changes I'm considering upgrading the temperature controllers and the modbus rtu. I'm running artisan and would like to stay with it. Does anyone have any recommendations? I currently have omron controllers.

MM1
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Postby MM1 » Jan 13, 2017, 9:46 am

Like others I have been eager to experiment with improvements to my roaster and as I mentioned in previous posts I am planning on making some major modifications to the controls, exhaust blower, and the heater box. Here are some pictures of a cheap, yet effective mod that I did that will most likely be resulting in a more permanent modification. I've never felt like I could control my ROR smoothly or get it up high enough at the beginning of the roast. A 3 lb roast on my 4.4lb roaster would take anywhere from 13-16 minutes with the same beans and trying to replicate the same settings. I noticed I was losing a lot of heat through the slotted doors so I added the bricks wrapped in foil and then covered the doors with foil as well. Its not completely tight because I was worried the exhaust blower wouldn't be as effective without out adequate airflow into the roaster. I have also attached a log sheet of the roasts I have done since doing this. The top 7 batches are 3 lbs. I then went to 3.5 lbs and finally the last two I went to 4lbs with really good results. The number on the far left is the TP. I am planning on doing the potentiometer mod that was discussed for the TJ-067 roaster since it is very similar to mine. I also bought a cheap, larger single phase blower that I will be installing soon. If the larger blower works then I will use that size for my three phase VFD controlled blower.

 
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