Hi

A quick question about the TJ-067, I was was planning on purchasing one these roasters and someone i know wants to purchase one as well, there are quite a few people interested in this roaster.

But the biggest question i have is, does the flame touch the drum? If it does, would it affect the quality of the beans?

With probat and other roasters does the flame touch the drum?

Thank you!

Correction, so now i have been told that the flame does indeed touch the drum, would that make much of a difference in quality, considering its more conduction and less convection?

A modern Probat is an indirect heating, "infra red" roaster which does a roast at a ratio of about 85/15 convection/counduction -- according to information on the Probat website. A North TJ-067 is a modern, "open flame" roaster which does a roast at a ratio of about 70/30 convection/conduction -- according to a generic remark about open-flame, classic drum roasters in The Roaster's Companion. I believe, (a) in either type of drum roaster, the roastmaster can increase the proportion of convection by increasing airflow; and also (b) that a double-walled drum makes for less conduction than a single.

But, indirect heating roasters allow the roastmaster to use higher Charge temps with less worry about scorching and tipping than an open flame roaster, providing the bean isn't very sensitive in the first place; for instance, you're not going to get away with Charging a honey process bean at a very high temp in either type of drum. Indirect heating roaster's drums preheat more quickly to even heat distribution across their surfaces. However, commercial type roasters have parts with greater thermal mass which take longer to fully preheat than the drum but which also affect the agility of the roaster, their face plates for instance.

Based on not much experience, my impression is that indirect heating roasters make it easier to reproduce roasts more accurately. But, that isn't usually much of a concern for people who don't roast and sell large volumes of specific blends which customers prize for their consistency.

If the roastmaster Charges at appropriate temperatures into a properly preheated roaster there's no discernible difference in indirect and open flame roasts. At least I can't detect differences in roasts of the same beans at similar profiles made in my open flame USRC from roasts in Bodhi Leaf's Diedrich or Klatch's Probat (small sample, panel of one, not blindfolded, biased in his own favor).

Rich

One other advantage of an open-flame design is that you can make faster course corrections mid-roast. The more insulated your drum is from your heat source, the farther ahead you have to plan when you are trying to make adjustments to your ROR. Obviously this comes at a tradeoff, because as you realize, one has to be careful not too apply so much heat (either at charge or later in the roast) that you risk scorching your beans.

FWIW this roaster does not easily scorch beans. It comes with optional perforated or solid drum, which exposes beans to flame differently. There is lots of fan control. It seems overbuilt like a piece of commercial cooking equipment.

Thank you for all your replies.

The manufacturer has suggested that he can adjust the burner in a way that it would not touch the Solid Drum.

What would you'll recommend?

abhishah wrote:
The manufacturer has suggested that he can adjust the burner in a way that it would not touch the Solid Drum.

What would you'll recommend?

I'm sure this is one of those things that got lost in the translation. It is highly likely that he means you can adjust the gas low enough that the flame doesn't touch the drum. Not a good solution as you will not have enough heat to profile a full charge. If you are really worried about the flame touching the drum, buy an electric model.

Personally, I have never had or heard of anyone having problem with this.

My suggestion is that you immediately cease to worry about it.

millcityroasters wrote:My suggestion is that you immediately cease to worry about it.

I agree. Steve imports and sells many of these, so that advice is solid.

The TJ-067 is a well-tuned roaster as it comes from the factory. I'm only getting started on mine. It has a perforated drum. Flame definitely touches the drum. On my seasoning runs I have started with a (too) high charge temp (400F), run extremely stale greens through it, and never got any tipping or scorching.

My gas roaster has an adjustable burner bar, so the flame height can be moved up or down. Another alternative would be to request a second set of jets with a lower overall height. I believe the TJ-067 has adjustable drum speed and air. That's makes three different variables to experiment with.

Abhi,
I am in Melbourne ( Aus ) and have been roasting on one of these for the last 10 months
There is nothing to worry about, on this or any roaster, the flame touching the drum.