My mod

[Damian]

I replaced the aluminum chimney with a glass tube (Borosilicate pyrex)
I can now view what the beans are doing easier.
I think I might make a hat type chaff catcher, to give even better viewing.

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[BenN]

That is great, and looking good.

Is tune easy to obtain?

I have told Kaffelogic is making those with glass hat as an accesarry among many things that we can buy later but you are one step ahead!

[Damian]

I got it locally.

Started on the chaff collector, works great, a lot easier to see the beans

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[BenN]

even better! great mod!

rescuing surface area of mesh affects to the air flow? i read something need to keep certain amount of area by dumping chief on back to back roast.

what if tube is taller and keep original length of mesh? either way i really like what you did here.

[Damian]

rescuing surface area of mesh affects to the air flow?

The tube's inside diameter = 70mm, therefore the cross-section area = 2848mm2 (pi r^2)
The circumference of the tube at the ID = 220mm (pi d)

To calculate the vertical height required for the same surface area as the tube opening, we divide the tubes open area by the circumference 2848/220 = 13mm, this is the minimum hight the lid can sit above the tube without restricting flow.

Similarly, the screened area can fill with chaff up to an average of 13mm from the top without restricting airflow.

i read something need to keep certain amount of area by dumping chief on back to back roast.

I dump chaff every use, not because of space, because chaff is very flammable.

[BenN]

I dump chaff every use, not because of space, because chaff is very flammable.

Yes, good point.

[BenN]

Chris, what do you think of this?
Replacement chimney just like his could be stabler, but maybe small glass section like 10cm tall in between existing chimney assembly and unit as a extra necessary?

I relay like this mod.

[Damian]

I made a new basket today, using a wire frame at the top, bent to the shape of the lid

I used teflon tape around the tube where the basket clamps, this gives the basket a lot more grip without needing to tighten as much. I was also hoping it would give some thermal insulation to the clamp, but it didn't make any noticeable difference. The steel clamp retains heat a lot longer than the glass or mesh.

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[kaffelogic]

This is a really great piece of work Damian. A really nice development. As Ben says we are investigating design options for chaff collector improvements, and this is a very inspiring design. Thank you for posting about it and we will use it as a source of inspiration.

For other users who are thinking of trying this mod here are a couple of pointers.

• The glass used must be borosilicate glass to withstand the heat. Ordinary glass will shatter. That is not very much fun and there is always a health risk when you have glass fragments that you need to separate out from a food product.

• The glass tube cut ends should be fire polished. This makes the ends stronger and also less sharp. The person cutting the glass tube should be able to do the fire polishing.

Here are the details of the glass tube we have found to work
OD: 75mm
ID: 70mm
L: 130mm
Longer pieces will work fine, shorter pieces will tend to leave some beans in the chaff.

We use black painted aluminium insect mesh Mesh size: 18 x 14 x 0.009". You can substitute virtually any aluminium or stainless steel mesh of the same or smaller mesh size as available from hardware stores, but be cautious of powder coated black mesh because the powder coating might not survive the temperatures as well as the black painted mesh.

[Damian]

I had mine cut to 150mm long.
I have been roasting 112g batches (works with my shot dose), I was still having a bean or two go over during cooling, so I reduced the "cooldown hi speed" speed from 17000 to 16900 and haven't had a bean go over since.

I have since replaced the stainless steel hose clamp with a cable tie (zip tie) which is Nylon PA 66. It doesn't retain heat as much as the SS, making it easier to handle.