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Thanks! Excuse the ignorance but when you say any "earth potential" are you referring to loose voltage trying to ground itself? If all the electrical equipment used in my roaster are grounded then why would there be any loose voltage? Or is there always fly aways!

JackH wrote:
Ben, I had similar issues with grounded type metal sheath probes. JimG said it might be a ground loop problem like you were describing. It is especially a problem with the two prong power packs we use to power the TC4 and the metal roasting pot.

My solution was to change the BT probe to a bead type. The response is much faster with the open bead too. My only concern is contamination of the probe from the oils and other stuff. I guess they are cheap enough to get spares.

He also suggested that you could also run a ground wire from a good ground to the TC4's ground pin.

jedovaty wrote:
Ben - I got the same ROR graph like you, with the up/down/up/down, try to adjust the filter setting in the code -- I forget exactly where it is, either in the pBourbon or aBourbon, but if you increase the number from the default of 85, it'll smoothen out (but add a bit of lag). I'm at 92 or 93, but think I need to go higher.{/quote}

Thanks I will look into it.

[quote}
What TO do you have, what kind of wattage is it?

I'm getting the same bean temp stalling you are at what seems like FC. I'm running more tests, but I theorize if we want to stick below 500 ET, either we need more heat intensity (e.g. another heating element), or move the bean mass closer to the heat source, or combine one of these with a different amount of beans. Think of it like heating up a cup of water with ice cubes. The temp of the water will not change until all the ice cubes melt.

I want to go as far as saying that the variac is causing this (like my router control), you'd be better off with something like the SSR with potentiometer, as it will provide the full heat source to help raise the BT while keeping ET right. However, I see others using variacs with similar setups succesfully, so I don't know what's we're doing different.

jedovaty wrote:
Hi Ben, take with a metric cube of salt with my no-experience.

I do 400g batches, which are ~50g off yours, not that much difference. I use 24ga for ET and BT: http://www.omega....t/5TC.html They're not very expensive.

Also, how are you making the connection between TC and the Arduino? Are you using all the TC wiring, or do you have any "normal" wires in the mix?

Inspecting the roasts I am still getting some tipping (no more scorching) but I'm currently playing with the volume of beans to see if I can find the sweet spot.

Koffee Kosmo wrote:

Regarding tipping
Its the amount of agitation your roaster set up is doing

I found that the mid level of the bean mass needs good agitation
So you may need to alter or add to your agitator arms so by its action, will agitate to both the lower and higher parts of the bean mass
You have seen my agitation test videos

KK

jedovaty wrote:
When I keep my ET (measured slightly above the bean mass halfway between the center and side of the colander) below 500 (I shoot for max 475), I have no tipping or scorching - give that a shot if you can!

jedovaty wrote:
Changing batch size and increasing my agitation speed only led to a more even roast (my sweet spot is 350g and agitation speed increased by adding two more arms since I'm not sure how to overclock a window wiper motor).

jedovaty wrote:
I like the idea of the center cap, I'm going to work on adding one as well since I get a few straggler beans just getting pushed around the center. Thank you for sharing that!

Koffee Kosmo wrote:


Regarding tipping
Its the amount of agitation your roaster set up is doing

I found that the mid level of the bean mass needs good agitation
So you may need to alter or add to your agitator arms so by its action, will agitate to both the lower and higher parts of the bean mass
You have seen my agitation test videos

KK

Q. Explain how the roaster agitates the beans?
A. I have spent countless hours fine tuning the agitator to have a complete mixing action rather than to push a mass of coffee beans around the roasting bowl
The main purpose of the agitator shape is to mix the beans in a specific way that is to move the beans from the centre out and back to the centre again
The action also cycles the beans from top to bottom in a helix pattern while also allowing the beans some intermittent rest time.