roaster control widget

[Tex]

Did you use a pot of boiling distilled water to calibrate your equipment or some other method? Someone told me that different controllers had different scaling as temps increased. The CAL Controls has a near-linear scale whereas the Watlow controllers had a curved scale.

I wonder how your controller handles a climb from 32° to 212°?

Where's you get the t/c's? I buy all of mine from Omega.

Nope the thermocouple amps compensate for the type of thermocouple used.... I was using K type thermocouple with J type amps....

I bought the thermocouples off ebay... 10 for $25.... for the development I didn't want to spend big bucks on them.

The J type I have are really nice ones, but I may move away from a bead to a thread-in grounded type.... can't decide yet.  I may play with both to see which is better.

I really like the ungrounded s/s sheathed probes (especially the 12" Teflon-coated ones I have - but they're type T); figuring the ungrounded t/c probe gives me a bit of buffer against the sudden rise in temps whenever the burner kicks in.

[Tex]

It's a poor trade off between ease of use and ease of tailoring the roast. The UFO/CO is looking pretty good right now!

You still have my shipping address for the sono?

Sorry dude, my shipping company doesn't deliver to South Vancouver, BC. Now if you were in the U.S. it might be doable. 

[milowebailey]

Sorry dude, my shipping company doesn't deliver to South Vancouver, BC. Now if you were in the U.S. it might be doable. 

I'll drive across the boarder

[Tex]

Sorry dude, my shipping company doesn't deliver to South Vancouver, BC. Now if you were in the U.S. it might be doable. 

I'll drive across the boarder

Not 'til you get over the flu my wife gave us. You'd be quarantined at GITMO.

[irunbird]

Nope the thermocouple amps compensate for the type of thermocouple used.... I was using K type thermocouple with J type amps....

I bought the thermocouples off ebay... 10 for $25.... for the development I didn't want to spend big bucks on them.

The J type I have are really nice ones, but I may move away from a bead to a thread-in grounded type.... can't decide yet.  I may play with both to see which is better.

I'm guessing the reading of either TC is nearly instantaneous, but from last graph it looks like there's a 20 deg F swing in temps-- is that right?  It looks like the PID is working since each peak looks only seconds from the previous one, but is that a healthy roast curve?

Ray

[milowebailey]

Nope the thermocouple amps compensate for the type of thermocouple used.... I was using K type thermocouple with J type amps....

I bought the thermocouples off ebay... 10 for $25.... for the development I didn't want to spend big bucks on them.

The J type I have are really nice ones, but I may move away from a bead to a thread-in grounded type.... can't decide yet.  I may play with both to see which is better.

I'm guessing the reading of either TC is nearly instantaneous, but from last graph it looks like there's a 20 deg F swing in temps-- is that right?  It looks like the PID is working since each peak looks only seconds from the previous one, but is that a healthy roast curve?

Ray

It's about a 10 degree swing and it does that somewhat at room temperature too.  We'll see what the correct thermocouple amps do.  I still suspect one of the thermocouples too.  I suppose I got what I paid for...

[MMW]

It's a poor trade off between ease of use and ease of tailoring the roast. The UFO/CO is looking pretty good right now!

You still have my shipping address for the sono?

Sorry dude, my shipping company doesn't deliver to South Vancouver, BC. Now if you were in the U.S. it might be doable. 

You could always let it stay in TX...I could be at an airport local to you in ~2 hours 

[milowebailey]

Update on the milowidget

Here are a couple of plots from weekend testing of the milowidget on the hottop.  All I am doing right now is turning heat on and off once per second depending on the bean temp vs the profile.... simplest method so far.

The 1st plot is of the first roast with 250 grams of green.  Note how good the ramp is and how closely the bean temp followed the profile, once it caught up with the curve.

The 2nd plot is of a roast of about ~75 grams of green.  I want to be able to control the curve no matter the green I put in (within reason of course).  With the smaller bean mass there is temperature overshoot both directions.  Also not how extreme the environment temp goes up and down too.  This is where the PID control will come in... now just to implement that in code..... that and a few small glitches in code here and there.... safety code (so the thing doesn't burn up)... 

Also found out that once the hottop warms up, it's more difficult to keep it on temp... odd, but I think that's because it's hard to cool it off quickly.  I'll need to tinker also with the fan and see how that affects the curves too. 

If only I didn't have a day job to distract me from my work

On a side note, my temp swing (see plots from a few posts earlier), I found out, is coming from serial port noise on my interface board..when my laptop is plugged in... unplugged the reading is stable (note difference from plots a week ago). I may need more shielding on the interface board or may have to move the thermocouple connector away from the serial port terminals.  Also the temp spikes are real readings also probably some sort of interference.  The thermocouple voltages are very very small so any higher voltage near them can cause spikes.  Looks like I'll need to enlarge my ground plane near the thermocouple inputs to the amplifiers.

[mp]

Thank you for the update Milo.  Good work ... I bet you are learning a lot.

If the Hottop is having problems cooling down I guess that would mean the heat retention properties are working too well.  You think a fan would cool it down to the degree that you would like?

 

[mp]

Hey Milo ... haven't heard anything on the Milowewidget for a while.  Are you nearing the point to start putting out kits for interfacing the Milowewidget to roasters espresso machines?

There is so much potential in your device.

 

[milowebailey]

Not to worry my friend.  I've been schooling myself in PID control.  The engineer must understand the math before he can add it.

An espresso machine would be cake.... one temperature to keep constant...

Now with the roaster, ya got fans, dampers, drive motor (those are pretty easy) but the tricky part is the variable mass... I could easily tweek the code for an exact amount of green.... but the tricky part is when the mass changes (gets really small)....

[mp]

I could easily tweek the code for an exact amount of green.... but the tricky part is when the mass changes (gets really small)....

Hmm ... so you would need something like a camera that can withstand temperature highs to the 600 degrees Fahrenheit?  Does the weight of the bean become affected with the mass change?

Hmm ... many interesting questions to be asked.

 

[milowebailey]

I'm sure it does, how much, that's the question.

With and espresso machine, you have a fixed amount of water you are trying to keep hot.... some leaves the boiler and is replace with cold water.... ya predict the change and monitor as you get close to temp and slowly turn off the heat.... easy.

with a roaster you have a moving temperuature, and a bean mass that is getting smaller, and is variable in wieght anyway (say you want to roast a 1/4 lb of Kopi Luwak... then jump to a full 1.4 lb of colombian....  from a control standpoint you cannot treat them the same.  I could probably have enter the wight but different density, water content of the bean would ruin that concept.

So in comes feed back from both environmental and bean temp.  I'm learning with the hottop that turning on the fan increases bean temp if environmental temp is high compared to the setpoint... kind of like a heatgun or convection oven...

it's very fun learning all these things

[mp]

Milo ... that is very interesting.

So you got the basic concept of the machine working right ... but now you just need to learn more about the characteristics of the beans so that someone could use the prototype Colombian and you would make adjustments to the program factoring weight and mass variables as well as the most desirable roast profile befitting that bean?

 

[yankeeNH]

* BUMP *

No news is good news about the Milowidget?

*nudge, nudge*