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calblacksmith
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calblacksmith
Joined: 25 Nov 2007
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Posted Mon Apr 4, 2011, 8:45am
Subject: Showtime oven conversion.
 

Len, I need to bounce some things off of you if I could.

I picked up a very new (not very used anyway) full sized Showtime oven at the Goodwill store for $25. It has most of what I need to get started. I was going to make my own mini Dietrich roaster and have looked into them a lot and with my machine/ metal working skills, it would not be too difficult.

Anyway, I saw that you make a conversion drum for the Showtime oven. I don't need to reinvent the wheel here so I am fairly sure I am going to pick up a drum from you. I have two concerns though. I see that you fill and empty from the end of the drum rather than through a door in the side. I am concerned about how long it takes to remove the drum then take it apart while hot. The second issue is the size of the holes in the screen you use for the drum and the air flow through them.

To get around the issue of handling a hot drum, I was going to fit a blower and a vent stack into the oven for rapid cooling. While roasting the vent would be mostly closed but open enough to get proper venting through the oven. When it comes time to cool down, I was going to open the top vent and turn on or turn up the power in a blower to force air through the oven. I want to roast no LESS than a pound at a time and 2 pounds would be better.

In reality, the oven is only a starting point, a shell for this roaster, not the end product. I also would like to fit a Trier (scoop to pull out beans to look at them during the roast) and I am still working on a way to support the drum so I would be able to open one side up to allow the use of such a device. This would also allow the use of the PID thermocouple to be IN the beans not the air.

I plan to use a PC to monitor and adjust a PID unit via RS232 connection while storing profiles on the PC. I have a simple to use program I purchased to fire a Kiln with that makes that connection to the PID from a PC through the standard serial RS232 port. I can program any length of ramp up time, hold time and ramp down time I wish simply by saying (not literally) start at 80F, take 15 minutes to reach 425 F, hold for 5 minutes etc. The PID provides constant feedback to the PC and the PC reprograms the PID to follow the program I specify.

Anyway, to the point, do you think that there would be enough air flow through your drum to allow for rapid cooling of the beans or will it need to be removed from the oven for this? Have you thought of using a hinged door on the side of the drum to allow rapid removal of the beans or has this proved too much hassle to engineer? What is a good working dose of beans for this size drum in pounds? More is better for me but I doubt I need to go to say 5 # at a time, not for a while anyway!

 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

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randytsuch
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Posted Mon Apr 4, 2011, 12:35pm
Subject: Re: Showtime oven conversion.
 

I'm not Len, but you might want to consider using the PID to control Environmental Temp (ET).  I have a TC near the heating element, to do this.

I have a 2nd TC in the bean mass, to measure Bean Temp.  I use BT mainly to decide when to end the roast, but also to monitor how things are going.  You could just use a meter with a TC input to measure BT.

Randy
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calblacksmith
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calblacksmith
Joined: 25 Nov 2007
Posts: 7,722
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Mon Apr 4, 2011, 12:42pm
Subject: Re: Showtime oven conversion.
 

Good points. I have gone back and forth with TC placement. My latest thought was it is the bean temp that really was more valuable but the ET needs to be controlled and the BT needs to monitored. Yep, that is the way it needs to be for sure.
The other points of air flow ect through the drum are still valid on my need to know list LOL! ;{D

 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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CoffeeRoastersClub
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CoffeeRoastersClub
Joined: 6 Jul 2005
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Location: Connecticut
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Espresso: Vintage La Pavoni Lever...
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Posted Mon Apr 4, 2011, 2:26pm
Subject: Re: Showtime oven conversion.
 

Hello Wayne.  I will try my best to answer each question you have, as follows:

"I see that you fill and empty from the end of the drum rather than through a door in the side. I am concerned about how long it takes to remove the drum then take it apart while hot. The second issue is the size of the holes in the screen you use for the drum and the air flow through them.

The drum just slides out of the ronco, and then you pop off one of the Ronco geat plate ends, and while holding the drum you point it into your metal bean dump container and the weight of the beans pops open the swing cap I have on the drum and the beans go out from there.  It is a pretty simple and quick process.  I recommend getting some ove gloves to handle the drum; or some kevlar gloves from mcmaster.com (I like those better, and I believe they were even less cost than the ove gloves I have).  Drum perfs are 1/8" diameter; drum construction is aluminum 20 gauge perf, end caps 16 gauge aluminum, interior fin angles 1"x1"x1/16" thick.  Also, depending upon the Ronco you get, the size of the drum will vary.

"To get around the issue of handling a hot drum, I was going to fit a blower and a vent stack into the oven for rapid cooling. While roasting the vent would be mostly closed but open enough to get proper venting through the oven. When it comes time to cool down, I was going to open the top vent and turn on or turn up the power in a blower to force air through the oven. I want to roast no LESS than a pound at a time and 2 pounds would be better."

The drums I make are up to 1 pound capacity green.  That is basically the upper limit to roast in any of the Roncos or George foremans.  The Roncos and foremans without any additional heaters inside do not get hot enough for roasting anything over 1 lb.  

"In reality, the oven is only a starting point, a shell for this roaster, not the end product. I also would like to fit a Trier (scoop to pull out beans to look at them during the roast) and I am still working on a way to support the drum so I would be able to open one side up to allow the use of such a device. This would also allow the use of the PID thermocouple to be IN the beans not the air."

Using a trier is a tough one for this type of drum roasting system.  I refrain from cutting into the sides of the drums as it weakens the cylinder structure; on top of that every time you open the door of the Ronco it allows alot of heat to escape which is a negative for the weaker heating system of the Ronco.  Takes too much time to get the heat back up.

"I plan to use a PC to monitor and adjust a PID unit via RS232 connection while storing profiles on the PC. I have a simple to use program I purchased to fire a Kiln with that makes that connection to the PID from a PC through the standard serial RS232 port. I can program any length of ramp up time, hold time and ramp down time I wish simply by saying (not literally) start at 80F, take 15 minutes to reach 425 F, hold for 5 minutes etc. The PID provides constant feedback to the PC and the PC reprograms the PID to follow the program I specify."

Problem again is the heating issue.  Basically the drums I make for the Ronco and Foreman are designed to just be put in the Ronco and let it go full heat.  Note that a typical roast of 1 lb. in a Ronco 4000 takes about 30minutes.  Adjusting the temp with a PID would really only extend that amount of time, not decrease it, again due to the lower max heat in the Ronco to begin iwth.  Due to such I would recommend against the PID.

"Anyway, to the point, do you think that there would be enough air flow through your drum to allow for rapid cooling of the beans or will it need to be removed from the oven for this? Have you thought of using a hinged door on the side of the drum to allow rapid removal of the beans or has this proved too much hassle to engineer? What is a good working dose of beans for this size drum in pounds? More is better for me but I doubt I need to go to say 5 # at a time, not for a while anyway!"

Since the drum capacity is 1 lb. max, just taking out the drum and dumping it into a pan and using a fan and another pan to pour the beans back and forth in front of the fan air flow works well.  However I can see an advantage of a high cfm vacuum setup that would attach to the ronco to such hot air out of the unit to be vented outdoors.  The only issue I can see is the initial high temp that may affect the vacuum unit.

Best regards,
Len

 
"Coffee leads men to trifle away their time, scald their chops, and spend their money, all for a little base, black, thick, nasty, bitter, stinking nauseous puddle water." ~The Women's Petition Against Coffee, 1674

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calblacksmith
Moderator
calblacksmith
Joined: 25 Nov 2007
Posts: 7,722
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Tue Apr 5, 2011, 5:13pm
Subject: Re: Showtime oven conversion.
 

Thanks Len. I have no problem adding heating elemtnts, making it 220, adding, removing metal, welding etc so while you needed to answer to the lowest skill level who may read this, my fab skills are a little more advanced than many here.

I was going to add the tryer in the side of the drum so opening the door was not in my thought process. This would require reinforcing the end of the drum cutting the end away to allow access for the tryer. I would also need to add an additional support for the drum.

The forced ventilation would be provided by a squirrel cage blower located on the cool side of the roaster so that the heat would not affect it.

I want the forced ventilation too cool the beans without removing the drum.

Like I said earlier I was planning on building a dietrich roaster from scratch but I thought I might be able to modify the showtime oven to work until I got a lot of my lazy backside in built the real roaster LOL

 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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calblacksmith
Moderator
calblacksmith
Joined: 25 Nov 2007
Posts: 7,722
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Tue Apr 5, 2011, 5:16pm
Subject: Re: Showtime oven conversion.
 

calblacksmith Said:

Thanks Len. I have no problem adding heating elemtnts, making it 220, adding, removing metal, welding etc so while you needed to answer to the lowest skill level of who may read this, my fab skills are a little more advanced than many here.

I was going to add the tryer in the side of the drum so opening the door was not in my thought process. This would require reinforcing the end of the drum cutting the end away to allow access for the tryer. I would also need to add an additional support for the drum.

The forced ventilation would be provided by a squirrel cage blower located on the cool side of the roaster so that the heat would not affect it.

I want the forced ventilation too cool the beans without removing the drum.

Like I said earlier I was planning on building a dietrich roaster from scratch but I thought I might be able to modify the showtime oven to work until I got
off of my lazy backside in built the real roaster LOL

Posted April 5, 2011 link


 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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dqts
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Joined: 12 Nov 2011
Posts: 53
Location: Federal way, wa
Expertise: I love coffee

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Grinder: Cunill Brasil, Capresso...
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Posted Tue Aug 14, 2012, 3:19pm
Subject: Re: Showtime oven conversion.
 

I know this thread is from a while ago.
I was wondering what ended up happening with your project?

I too just got a Ronco Showtime and am in the process of figuring
out how to convert it.

I used a Hominy can from Winco to be as my drum. I hate having to handle the drum
after the roast and want to be able to cool the beans in the unit.
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