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CafeMasy SCR-300 Roast
Stop Laughing!

I wanted something to test bean movement using a paddle type bean agitation (That I could mess with) and I thought I should do a roast.

Guatemalan Beans 227g Thermo Knob set to 220C
Pre-heat 5min plate is at 300c most of the outside.
So the plate was cooler in the middle at 250c and at 3 o'clock the outside was about 90c less (210c) 6, 9 and 12 at 300c.

Bean rotation/agitation was ok clockwise but it just pushes the beans when moving counter clockwise.
This unit collects moisture on the glass (Smells like boiling the beans) and of course burns the chaff at the end of the roast.
I lifted the lid to get rid of the moisture but should have used a fan to try and push out as much chaff as possible when I do this.

FC was at 10min 10sec, stopped roast at 13min30sec, Beans at 220c and 15% loss. So close to Full City+.
Chew test was a little bitter but not bad, will need to see how it taste in a few days.
I kept the Bean movement going clockwise and I think the roast evenness is better than I expected.
Could be better used as a base for a turbo open setup, than roaster by itself.
As is now Is the electric equivalent of pan "roasting", the only design performing majoritary contact heat transfer, the worst possible.
Very low convection or radiation in the factory configuration.
A TO on top would fix all issues: add convection and radiation, airflow to remove smoke and chaff, and shorter times.
Yep, it has issues and is cheaply made.
Original idea was to use it as a test bed for a few ideas around bean movement. Once I do this I will probably put a ring on it and plop a TO on top to test that out as well, I have one sitting in the closet. Spring is coming and I could roast outside on warm days now so the mess won't be an issue.

If I make a TO for inside roasting I need to contain and vent it. Space is limited.

I was surprised on how short the roast was using 227g, some users on YouTube were roasting 170g at 15-21 min? Medium roast would be less then 13min? Let's see how bad the coffee is!

Oh well for fun I might put a ring on the top and add a CPU fan with a pot to adjust the air and push out the chaff and moisture...
Or the aluminium cyclone that became so popular here...

Paired mine with a 4" duct inline fan, that is full metal, so no plastic parts to have issues with hot air exhausted during a roast
This fan also fit very nice in the same shape as the cyclone, having the same diameter as the triangle defined by the holes of the cyclone mounting ears.

If you have the tools to bend one inch soft copper pipe, under a very small radius of one inch, then such cyclone can be tinkered at home using a stainless steel drink shaker.
Most videos I see use an exhaust hood type ventilation but can positive air flow be added to the roast chamber in the TO to push out exhaust and chaff or will that just wreck the internal vortex?
push out where? through which exhaust?

The chaff follows the vortex path, i.e. a descending spiral along the outer wall, so installing a slot for chaff trapping (pull) tangential to the oven wall seems the most intuitive action, imo.
The first projects used such a simple design, just a slot in the wall, and a filter to catch the chaff, without any external pull.
The fan linked above draws a quota of air enough to not cool the oven too much, about 4-6 degrees, that can be easily compensated by 2% of power up.
Without the fan, the internal oven pressure of the vortex is not enough to push the chaff through the cyclone.

Also, for a complete picture, you should be aware that inside the TO there is a second turbine, not visible, which role is to cool the outer plastic dome from the heat radiated by the metal plate who serve as lamp support.
That turbine exhausts a significant amount of smoke too, through the ring of slots that can be seen right above the glass.
Have you posted any video or pics of your ventilation system for the TO?

I was not aware the upper turbine can pull the air from the cook chamber?
Will have to watch that tear down video and pay more attention.

I see a few holes in the tin and a bushing or spacer on the shaft?
I think it's just a plastic spacer so if you seal that hole it might melt.
Edited by HarryDog on 03/19/2023 9:02 AM
Not a strong pull, only what can pass through holes of the thermostat and lamp wiring, some 3-4 mm holes. And the shaft hole, is not sealed.
But enough for the smoke, or smells in the regular usage.

No plastic in my TO, other than the outer dome.
Inside is metal only... the lamp plate is 400 C on the bottom/inner side ! Shock
Interesting, the video shows a white spacer on the shaft, not sure what it's for?
In the video you posted you see the white plastic spacer at 30 seconds.

Maybe seal to it on the top cooler side?
Edited by HarryDog on 03/19/2023 4:11 PM
In all the lids I dismounted it was metal, not plastic.
Could be an alu alloy, thus the whitish appearance.
There is no sense to seal the shaft only, when the plate is stuffed with holes, check attached.
It's simply a spacer that define the distances between the lamp mounting plate and the two turbine disks.
renatoa attached the following image:
Some air flow might be important as the thermal switch is in the rectangular hole. Going to do some testing and see how it goes. Maybe it will be an outside roaster for now.
What I didn't heard so far is about the size... is that cafemasy pan diameter same of a standard TO, i.e. 32 cm ?
If not, the airflow path inside become a bit difficult to evaluate...

Does your turbo oven came by default with an extender ring ?
It is the perfect accessory to build such an oven, the 8 cm height ensure the minimal distance from beans to lamp.
I mean the SS piece in the attached image
renatoa attached the following image:
The Cafemasy base is 9 inch that bevels up to 10.5 inch where the lid sits. This base is about 1.5 inch deep. My TO lid is 31.5 cm.

No extension ring, was thinking a 4 inch ring would work. I don't think I'm going to find any Stainless steel around locally to make one. Maybe I can find a pan at the dollar store that might work, just cut the bottom out. Maybe a spring form pan, should work?
People use something like this and form it in a cylinder
[url]https://www.lowes.com/pd/Steelworks-4-ft-x-1-5-in-Aluminum-Solid/3053635 [/url]

Aluminum is soft so would be easier to work with.

Or go look for a cake pan like you said.
Edited by renatoa on 03/20/2023 2:06 PM
How food safe is non stick coating? The 10 inch spring form pan is almost perfect when expanded, only 1 inch left in the pan so I could separate it and use a couple of bolts to make a gap for the chaff. It's only 3 inch high so going to be a bit under in volume 5.82 liters (Base + Ring). What is the calculations for the TO lid .5 liter?


When PTFE is heated to over 280℃ (536℉), it releases toxic particles and acidic gases which are toxic when inhaled.

If roasting into SC, you are dangerous close to this limit, imo...

6 litres volume is ok, the distance is the critical part for this design, you should keep the lamp screen plate, else the direct IR would add too much heat in the browning phase.
So ignore the posts where some of us are discussing about various patterns to cut the lamp screen plate, in order to add a variable amount of IR, those are for taller designs.

Also, prepare to start with lower power levels than you are expecting, for example in my 9 litres oven, roasting of 333 grams requires a start/preheat power level of 32%, raising to 64% in the start of browning phase, then decreasing to 58%
For 1300W lamp and 8-9 minutes roasts.
If you have no power regulation electronics for the start, you can try the diode trick, will cut the power to exactly 50%, and I think it's a good level to use from start to the end, for 6 litres.
Probably pushed past that limit when I had the base plate pre heated to 300c.
I have an adjustable voltage regulator some where? Could plug it into that. How does it effect the fans? Would that work for now as I don't want to take it apart yet. If not will try a roast just adjusting the heat.

The screen is still on and is a thin grid of rectangles cut into it, might only block about 30%? Bulb is a 1300 watt 120v.

The screen will be 11.5cm from base plate, when 227g beans are roasted about 9cm from screen?
The fan is of induction type, which can't be regulated by voltage, but a combination of voltage/frequency.
Changing voltage of the whole oven will keep the same fan speed down to a point where it will stop sudden.
No idea what power % or voltage will happen for your lid.

So... you have to separate the heater circuit, if you want to regulate its power, by any method.
Not rocket science, the simplest is to tap on the thermostat plugs.

Please, can you post a screen picture? sounds different than what I know so far...

Distance is good, 3 inches is the lowest safest distance for IR to not burn excessive any organic food.
Edited by renatoa on 03/21/2023 8:35 AM
Not sure what picture you are looking for?
The TO unit is a Flavorwave.

Should I use the term Variac? Might be a better description.
Don't think that will work, it will draw too much current?
Some Pictures.
HarryDog attached the following images:
variac_3.jpg bottom_1.jpg base.jpg whole_unit2.jpg

Edited by HarryDog on 03/21/2023 8:32 AM
Nice, your voltage regulator is actually a true voltage variator, more exactly a self transformer, that delivers a clean and complete sine wave.
Not a chopped wave, as a SCR.

The grid looks strange, a lot of IR will pass, making your final approach of the roast tricky.
Check here: https://homeroast...post_76484 ... how are looking KK and my screens, and the discussion about the kind of cuts we did to improve airflow, but keep IR under control.

Regarding chaff exit opening... are you sure is the right sense of rotation ?
For most lid models I know the vortex rotation is CCW, the opening that I see in the picture suggest a CW vortex rotation.
Definitely confused on the vortex direction. Can switch if I need.

Was wondering about the IR as well, this units screen is very open.
How does the coffee taste?

Aroma: Sweet Brown sugar with a pleasant Floral note.
Taste: Light acidity, sweet floral note with a rich full body, cannot pick out the fruit but as it cools I get a slight fermented stone fruit, the aftertaste has a little off tasting bitterness and this I believe is from the burnt chaff.

This is a better cup then I expected, can see why the youtubers say it's better then store bought and I like how contained the acidity is, it allows the coffee to shine through.

Can it be better, yes.

1. Remove moisture and chaff.
Filter and re-cycle the air using a fan and extension ring like on a TO?
2. Add a better paddle system to move the beans.
3. Vary the temp a bit like a normal roast, this is a maybe.

I have already put a ring on it to add a TO and tested my first paddle that works good both ways but slightly better going in CW direction, better movement then the original. Going to try a flatter paddle for next version.
Well first TO-CafeMasy roast.
Guatemalan 15% roast level just under Full-City+
Fairly quick at 6:45 total roast time.

I have been sick so taste and smell is a bit off but today is my roast window to beat about 7 days of poor weather.

I think the aroma is great already, the halogen must add a bit to the Caramelization stage?

The chew test was good almost no bitterness detected.

Vortex direction? Now I moved the ring to ccw position and it looks like the chaff is still going in CW direction, most came out as the fan does act like a blower and drives most of the chaff out anyway. Will change the ring for the next roast.

Taste test on Wednesday.


HarryDog wrote:

...the halogen must add a bit to the Caramelization stage?

Discussed here two roast scenarios, with and without lamp screen plate:

... so, yes, IR addition add... more than a bit, imo...
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