Rotisserie roasting (electric oven)

[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.

[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

[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.

[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.

[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)

Nope already checked that

[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

[JavaB]

Re: Rotisserie roasting (electric oven)

Disconnect the thermostat and connect the elements directly to the SSR. The SSR is connected to the PID controller which then controls the elements. So in essence the ovens thermostat gets bypassed and is replaced by the SSR and PID controller. Am I correct or do I not understand something?

Correct

Looking at the thermostat...it seems it only has one wire in and one wire oto the thermostat are the two wires I put in to the SSR.

Most SSR have two pins/terminals for controlling input and two for the mains being controlled.... some have an additional terminal on the mains side for a neutral connection - but thats not common....

What current does a mini electric oven pull? Just wanting to know so I know what SSR to get.

Divide the power rating by 240 to get the current...... make sure your SSR can handle a peak current of twice that value (inrush of current when the elements are cold and the resistance is lower)

[Dimal]

Re: Rotisserie roasting (electric oven)

Hi Wushoes,

Heres a link to a site with info on a range of suitable controllers for applications such as your Rotisserie Oven Roaster, or ROR for short . Quite a few CS members have used this company to source hardware in the past, including myself, and they are very helpful where CS members are concerned so dont forget to mention that if you make any serious enquiries. All the best,

Mal.

[Wushoes]

Re: Rotisserie roasting (electric oven)

hmmm so I guess I spent money on an datalogging dmm for nothing hey? :P I know there are some PIDs that datalog too...straight to PC...hmmm

This is what I understand so far about what I need to do.

Disconnect the thermostat and connect the elements directly to the SSR. The SSR is connected to the PID controller which then controls the elements. So in essence the ovens thermostat gets bypassed and is replaced by the SSR and PID controller. Am I correct or do I not understand something?

Looking at the thermostat...it seems it only has one wire in and one wire out....but I havent popped the hood off to confirm...too much trouble. Dont SSRs require two inputs? Or is it that Im looking at it totally wrong....that the two wires that lead in to the thermostat are the two wires I put in to the SSR.

Seriously considering PIDing out my oven...even though I got it for $50 new. What current does a mini electric oven pull? Just wanting to know so I know what SSR to get.

Note to self....get SS drum made.

[robusto]

Re: Rotisserie roasting (electric oven)

Im very happy with the Auber brand PID which keeps my Silvia to within a fraction of a degree of set point. This particular model does NOT have a ramp and soak function --because a steady temperature is required.

But the brand does also make one, slightly dearer, which does have ramp and soak. Of course, the seller is a non-sponsor so I wont mention the name.

I have a toaster oven, and the lag there appears to be considerable and is determined by the thermostat hysteresis and the heating elements.

A coffee machine boiler such as the Silvias is a mere 300 millilitres capacity, and the heating element around 1100 watts -- so you can imagine the response time is super-quick. So quick we need a PID to prevent over-shoot.

A rotisserie oven is much, much bigger, but with elements of the same capacity (top and bottom). Naturally, response time is going to be slower.

But a PID will at least take out the hysteresis (if combined with a solid-state relay) out of the equation.

Again, if the lag is 10...15...20... even 30 seconds, I doubt whether that would affect the roast profile over the course of 15 minutes. When I roast over the barbecue, even with quick-reponding natural gas, Ill turn burners up or down for 2 - 3 minute stetches.


--Robusto

[Wushoes]

Re: Rotisserie roasting (electric oven)

Are you saying the lag isnt that long?

Have you got any examples of PID models or brands that I can look at? Would something like the Cold Fusion TET7100 or Auber SYL-1512 do? Theyre quite cheap in USD...but factor in exchange rate and shipping...should be less than AU $100?? Do I need an SSR to control the elements?

Having ramp and soak settings will enable me to create whatever roast profile I want...but I need to know how fast the beans roast in the oven first! Otherwise its totally guessing....so I guess thats where a normal PID would come in to its own...sorta like the Gene Cafe where you can control the temperature with a radial dial....but then the Ramp/soak PID would be more like a Hottop with preset roast profiles (again I need to know the profiles to program them in) with the ability to change the temps instantaneously like the Gene Cafe also

Cheers,

David

[robusto]

Re: Rotisserie roasting (electric oven)

A ramp and soak PID would be best, because it allows you to set tailor-made roast profiles.

But any of the PIDs weve utilised for coffee machine boiler control should do the job (250º is well within their control parameters).

Without the ramp and soak function, itll simply keep the temperature at the pre-set.

You can change the temperature setting up/down at any time, and its then up to the PID to determine how quickly to respond to the new setting.

I shouldnt think that a lag of a few seconds would be meaningful to the profile you are trying to achieve.

-Robusto

[Wushoes]

Re: Rotisserie roasting (electric oven)

Yeah...I had posted another thread about thermostats and PIDs for controlling my oven...but decided to delete the thread.

So yeah....you think any cheap PID will do? Because I know some PIDs will not work on Silvia...or very hard to get working without a lot of tweaking...I remember reading a thread on some PID you can buy in Australia from a distributor and it was hard to get going on Silvia.

Also with PIDs can I instantaneously change the temperature (I know the oven will lag behind in getting to that temp)...but essentially...I am able to set the temp digitally at any time I wish?

[robusto]

Re: Rotisserie roasting (electric oven)

What you need is a......PID! Yes, a PID, after all, controlling ovens and kilns is what they were desgined for in the first place.

A PID with a ramp and soak function which enables you to tweak to your hearts content.

Of course, its going to cost more than the oven, but what the heck. Throw away that thermostat with its unacceptable hystereses, and go for broke...

--Robusto