Rotisserie roasting (electric oven)

[Wushoes]

Re: Rotisserie roasting (electric oven)

I will give it a go. Or maybe I should just hook it up to the oven and stop dicking around.

Cheers.

[Sparky]

Re: Rotisserie roasting (electric oven)

You may have a reverse action SSR output. If so you may be be switching the SSR off rather than on. Although the LED on the SSR would suggest otherwise. I have a Fuji PVR3 which is supposed to have a reverse action SSR output. I havent had time to tst it yet.

BTW, you have a very cool project going there.

Cheers,

Mark.

[Wushoes]

Re: Rotisserie roasting (electric oven)

Good news. Preliminary results say the PID works!

Ive replaced the oven thermostat with the PID and SSR...and it seems to work. Unfortunately my DMM thermocouple carked it, so I cant say for sure how accurate the PID is. I only have a free standing needle type oven thermometer in there to make comparisons.

I had the SV at 230 deg C. The PID overshot by about 1.2/1.3 deg C...turned the oven off after that so I didnt really give the PID a chance to settle the temp down.

So far so good.

[Wushoes]

Re: PIDd rotisserie oven roaster setup

Here is the complete set up. I am almost ready for my first roast.

[rowdee]

Re: Rotisserie roasting (electric oven)

Looks fantastic, we are all waiting...

[MattG]

Re: Rotisserie roasting (electric oven)

Your setup is looking good. Where is the thermocouple positioned in the oven? Im concerned that if it is not close enough to the bean mass your set temperatures may be too low. I was unable to reach 1st crack in under 15 minutes and 2nd in less than 20 minutes in the oven you grabbed from me. Try to aim for 11-13 minutes for 1st and 15-17 minutes for 2nd crack.

Interested to see how your first roasts go.

[TC]

Re: Rotisserie roasting (electric oven)

Your setup is looking good.  Where is the thermocouple positioned in the oven?  Im concerned that if it is not close enough to the bean mass your set temperatures may be too low.  I was unable to reach 1st crack in under 15 minutes and 2nd in less than 20 minutes in the oven you grabbed from me.  Try to aim for 11-13 minutes for 1st and 15-17 minutes for 2nd crack.

Interested to see how your first roasts go.

Hmm- I wonder if we should worry that much about thew 15 min? I remember Peter saying that they roast for 30 min at the last bean day. Do we roast just the outside of the bean if we rush it too much?

My hottop is more like 22 min to 2nd and the Gene is also giving much better results slowed down rather than rushed through in 15 min.....

[JavaB]

Re: Rotisserie roasting (electric oven)

Hmm- I wonder if we should worry that much about thew 15 min? I remember Peter saying that they roast for 30 min at the last bean day. Do we roast just the outside of the bean if we rush it too much?

Yep,

My best roasts with the Corretto were those where I took it slowly slowly.... ended up just shy of 30 minutes....

I also found a slow steady increase in temp to first crack (rather than hit the beans with 250C straight up)..... and then a very slow increase after that so it takes quite a while to get to second produced the best flavour in the cup.

[MattG]

Re: Rotisserie roasting (electric oven)

Hmm- I wonder if we should worry that much about thew 15 min? I remember Peter saying that they roast for 30 min at the last bean day. Do we roast just the outside of the bean if we rush it too much?

My hottop is more like 22 min to 2nd and the Gene is also giving much better results slowed down rather than rushed through in 15 min.....

With the electric oven I found that roasts hitting second crack in more than 20 minutes displayed greater signs of tipping and ended up tasting baked.  Roasts that were under 18 minutes generally tasted better.  Perhaps a slower ramp up and lower temperature up to 1st crack is the key. However, with a rpm of about 3-5 in the electric oven (compared with 40+ rpm in commercial roasters), youd think that there would be more conduction heating than convection heating since the beans spend more time in contact with the drum than in the air.  Perhaps this causes more scorching and baking of the beans or maybe the temperature is too high for such a low rpm.  I havent run enough roasts or profiles to provide any conclusive results either way.  Im currently running a bunch of profiles to test this out so should have some results in the next few weeks.

However, sorry wushoes for hijacking your thread.  Let us know which profile you find best.  

[TC]

Re: Rotisserie roasting (electric oven)

Will be interetsing to find out, Matt....

I wonder if you could set up a gearing system to get that drum moving a tad quicker? A gear runs off the original motor and you offet the drum on another gear....Gotta have potential?

2mcm

[Wushoes]

Re: Rotisserie roasting (electric oven)

The thermocouple is located on the right side wall (closest to the control panel side) mounted underneath the line of the rotisserie rod at the same level as the bottom of the drum. If you look at the photo on this page above you will see the thermocouple going in through the front door and mounted off the wall slightly by first putting on a bolt from then placing a nut on the inside, then mounting the TC on and then using another nut to hold it in place.

Of course this is not bean mass temp, but I can always bump up the PID temp to say 260 deg C and see what happens.

I have since modified the design since as the thermocouple going through the front door was only temporary....it is now a lot neater and goes through the back.

Perhaps a photo is in order...Ill post one up later...you are probably all confused from what I wrote above

[Wushoes]

Re: Rotisserie roasting (electric oven)

Okay heres a photo of the location of the thermocouple.

It is about the bottom level of the drum bolted on the side of the oven wall....right underneath the line of the rotisserie rod.

Any ideas of how to get it a lot closer to the bean mass?

My first roast indicates it is well off from bean temp as the beans roasted with temps showing at around 180-190 deg C on the PID unit. First roast details here: http://coffeesnobs.com.au/YaBB.pl?num=1170750492/0#0

[Wushoes]

Re: Rotisserie roasting (electric oven)

I have answered my own question above....

Very simple solution and should have thought of it a lot earlier. The TC is now smack bang in the middle of the oven held on a bolt and some nuts, the same method used to hold the TC on the side wall of the oven. Perhaps some photos are in order.

The difference between the DMM and PID readings are almost the same....finally...some success! It seems however that the PID readings are very slow to update in comparison with the DMM. Is there like a refresh rate I can change on the PID?

[Dimal]

Re: Rotisserie roasting (electric oven)

Is there like a refresh rate I can change on the PID?

There could be a functionary setting that is averaging the input from the t/c prior to feeding it to the PID algorithms and as a result, there will be an apparent delay in updating the PV Display. If you do a search for the make, type and model of your controller, you may be able to locate a setup manual or some such thing and then go from there.....

Cheers mate,
Mal.

[Wushoes]

Re: Rotisserie roasting (electric oven)

Ill have a look through the PXR4 manual later tonight. I hate reading that damn thing.