Rotisserie roasting (electric oven)

[robusto]

Re: Rotisserie roasting (electric oven)

My guess is the oven would pull 10 amps max at a steady state --- all elements on. Not many domestic appliances exceed that figure.

The rating should be on the outside somewhere, possibly underneath: 2400 watts would be approx 10 amps, 1200 watts would be approx 5 amps.

-Robusto

[Wushoes]

Re: Rotisserie roasting (electric oven)

Nope already checked that

[JavaB]

Re: Rotisserie roasting (electric oven)

Well in that case I would assume the current draw is 10 Amps.....

Better to err on the side of safety!

[Wushoes]

Re: Rotisserie roasting (electric oven)

In other news...today I walked in to a 2 dollar shop and found a sieve that happened to be 15 cm in diameter.....*lightbulb* "2 of these can make great end caps of a drum!" says the coffee snob inside. Purchased two of these for $3.50 each.

Went to Bunnings and got some L shaped brackets and some wire mesh and off I went to my garage to get my drill and rivet tool.

End result....well see for yourself....all aluminium drum

Things I am unhappy about:

>> The brackets used as bean agitators did not reach all the way to the ends of the drum....and are fixed permanently to the drum now. The bracket is 200mm long. My drum is about 250 mm long...so the it is missing a good 20mm off each end...hopefully this wont affect the roasting ability

>> Bracket has many sharp edges.....but I can live with it....would have filed it down...but couldnt be bothered.

>> The bracket/agitator height is only 20mm...would have been happy with 25mm to 30mm

The drum is still incomplete. I still need to put a mounting mechanism so the rod can be inserted through the drum...easily done.

[Dimal]

Re: Rotisserie roasting (electric oven)

Cool and Inventive Wushoes 8-)

What if you drilled out the rivets holding the "tumbling" brackets in place and moved them all the way to the opposite end of the "open" end of the drum and then refixed them in that position? You could then just tilt the "open" end up slightly so that the bean mass is encouraged to move away and towards the "closed" end. Wouldnt have to worry about the gap at one end then :-?

Mal.

[robusto]

Re: Rotisserie roasting (electric oven)

Good work, Wushoes.

I wouldnt lose any sleep over the brackets -- with all that agitation going on the beans will get sifted through.

Try it first, in a dry run. Put in some beans and spin it around in your hands to see how they behave.

If it still annoys you, remove ONE bracket, and move it to the end. Then move a SECOND bracket to the other end.

-Robusto

[bluedevilfish]

Re: Rotisserie roasting (electric oven)

Great job Wushoes,

Dont worry about the gap at the end of the fins. If they are positioned too close to the ends youll a few beans stuck down there. Not a problem but youll have to dislodge them with a screwdriver before the next roast.

[Wushoes]

Re: Rotisserie roasting (electric oven)

Thanks guys. Just tweaking everything at the moment. The rotisserie rod doesnt seem to sit in the oven motor deep enough and sometimes pops out stopping the drum from rotating which would be disastrous mid-roast.

Trying many methods to get the rod to push in to the motor more.

[Wushoes]

Re: PID programming

Thanks to MatthewG, I now have a Fuji PXR4 PID controller to replace my oven thermostat with.

Ive been playing around with the settings and trying to program a roast profile in to the PID unit.

Heres a mock profile (lookng for suggestions to change)


Preheat oven to 250 deg C. Ramp for 10 minutes. Soak for 2 minutes.

SV-1 - set value target temp 1 - 250 deg
TM1r - ramp time - 10 mins
TM1s - soak time - 2 mins

Open oven door and load drum which will cause temp to drop approx 30 to 50 deg C. Ramp to 230 deg from whatever temp the oven drops to....(approx anywhere between 200 and 220 deg C from past tests with a thermocouple, add to the fact that the temp will further drop as the beans and cold drum will absorb more energy.)

SV-2 - 230 deg
TM2r - 5 mins
TM2s - 5 mins [hopefully will take me to first crack]

Decrease temp and coast to 2nd crack

SV-3 - 220 deg
TM3r - 5 mins
TM3s - 15 minutes [doesnt matter how long as I can pull the roast at any time]


Those are my mock settings. Looking for lots of input.

Of course I can always manually control the PID in immediate response to what is happening to the beans. :P But I think programming a roast profile would be cool.

Cheers.

[muppet_man67]

Re: Rotisserie roasting (electric oven)

setting the standard. Now we just need someone to pid their heat gun/bread maker set up. 8-)

[Wushoes]

Re: Rotisserie roasting (electric oven)

Or popper....that would be insane to see $300+ worth of electronics on what is essentially a cheap heating element

[JavaB]

Re: Rotisserie roasting (electric oven)

setting the standard. Now we just need someone to pid their heat gun/bread maker set up. 8-)

Ive thought about it (my heatgun is already under triac control to better than 1%) but somehow I think it would take the fun out of the process...

I like to tweak the heat knob and watch the resultant temperature change - with anticipation that Ive done it right :

Also because of the relatively small thermal mass of the roaster compared to the bean load..... it could be a difficult exercise...... there is probably a 20+ second delay in seeing the result of the change. Humans are (generally) better a fuzzy logic than computers!!!! ;D ;D

[Wushoes]

Re: Rotisserie roasting (electric oven)

How can it take the fun out? You can tweak to your hearts content with a PID unit...even go as far as programming a roast profile using the ramp and soak functions.

[Wushoes]

Re: PID and SSR question.

So I was mucking around with the PID and SSR today and I realised that there was no voltage on the output terminals of the SSR even though the SSRs LED and the C1 light on the PID unit are solidly lit.

To get the PID and SSR like that I set the Set Value to a much higher reading than the thermocouple eg 200 C, whilst the thermocouple was only reading room temp. If this is the case then the PID would tell the SSR to give the heating elements some power to raise the temp of the system the PID unit is supposed to be controlling.

Why then, is there no output voltage on the output terminals of the SSR? (measured the output terminals with an auto ranging dmm)

[JavaB]

Re: Rotisserie roasting (electric oven)

Do you have a load attached.... some solid state relays have a minimum load requirement.... stick a light globe in as a load.

and a DMM of 10+ Megohms just wont cut it as a load!!