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fixed sunbeam grill over/under's heat distribution [UPDATED]

 
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drcrash
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Joined: 04 Sep 2006
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Location: Austin, Texas

PostPosted: Fri Oct 06, 2006 3:13 pm    Post subject: fixed sunbeam grill over/under's heat distribution [UPDATED] Reply with quote

I think I've pretty well fixed my little 12-by-18 over & under's hotspot problems, with a couple of hacks. (It uses the problematic Sunbeam Deluxe Portable Electric Grill as a heater.)

First I put in a diamond-shaped perforated aluminum reflector under the heating element, made from a disposable grill topper. This blocks some of the IR in the middle, and redirects some of it toward the edges. That gets rid of the great big hot spot in the middle of the oven.

[EDIT Jan 1 2007] Here's a picture looking up into the oven:


And here's a picture of the basic structure, during a preliminary test-fit, with topless/bottomless rigid box to support platen and the legs that hold up the oven:


This is before cutting things to size and bolting them together, and adding the aluminum flashing box.



Then I made a rectilinear aluminum box (four sides) to extend the sides of the oven six inches below the plastic, and positioned the plastic about an inch inside it and about five inches below the heating element.

The idea there is to

(1) reduce any remaining small hotspots by moving the plastic further from the heating element, giving the IR more time to spread out before hitting the plastic, and

(2) reflect any stray light back toward the plastic, to keep it from getting away, so that heating is still efficient at the greater distance.

(I figured a few more inches would do it, because the mild hot spots I got after adding the diamond reflector were only a couple of inches wide.)

So far, these two hacks seem to work great. There don't seem to be hot spots anymore, I don't get undue thinning in the middle, and I get good detail all the way to the corners.

The downside is that it makes the oven 6 inches deeper, which I don't like. (I want the whole thing to be as small as possible when disassembled.) I think I can fix that by replacing the aluminum box with a set of six-inch-wide "barn doors" around the edges, and fold them flat on the bottom of the oven the when it's not in use.


Last edited by drcrash on Mon Jan 01, 2007 9:25 am; edited 2 times in total
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drcrash
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Joined: 04 Sep 2006
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Location: Austin, Texas

PostPosted: Fri Oct 06, 2006 3:16 pm    Post subject: Reply with quote

Oops... I said "below the plastic" here:

Quote:
Then I made a rectilinear aluminum box (four sides) to extend the sides of the oven six inches below the plastic, and positioned the plastic about an inch inside it and about five inches below the heating element.


I meant to say "below the heating element." I'm extending the walls of the grill down several inches and putting the plastic near the bottom.
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drcrash
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PostPosted: Mon Jan 01, 2007 9:33 am    Post subject: cheap rectangular electric grills available again, I think Reply with quote

Some of you probably know that nobody's been able to find the cheap little rectangular electric grills for some time now, making it harder to slap together a nice little over-and-under.

Good news, I think:

It looks like Wal-Mart is selling little rectangular electric grills again. They're branded "Uniflame," but I think it's the successor model to the Sunbeam Deluxe Portable Electric Grill, which was really a Uniflame grill with Sunbeam's logo on it. (Or maybe one owns the other, or something.)

http://www.walmart.com/catalog/product.do?product_id=5280780

Hmmm, after looking up that link, I just noticed that the power gadget attaches to the front, not the side... so it's apparently got a different heating element in it. Hopefully it's a rectangular element, and the same basic design & mods will work.
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jegner
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PostPosted: Thu Jan 04, 2007 10:56 am    Post subject: Reply with quote

Good info. Thanks for sharing!

Jim
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drcrash
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PostPosted: Fri Jan 05, 2007 11:04 am    Post subject: new portable electric grill element; cellphone camera IR Reply with quote

I saw one on display, opened it, and took a really lousy cellphone camera picture:



It's got a rectangular element. Looks good. Maybe better than the old one.

They've changed the thermostat arrangement a bit. There's a metal thing connecting the thermostat probe to the coil. So the thermostat must mosly measure the coil temperature, not the oven temperature.

That sounds bad, but might actually be better. The old thermostat was useless. This one might work for setting power, if not temperature. That would be cool, because mine's too hot and I flip it on and off a fair bit.

By the way, my cellphone camera is bad for regular pictures, but like a lot of very cheap digital cameras, it can see in the dark a little bit.

Here's a picture of a new little cheap oven I'm making, out of a 2-burner
hot plate and some disposable roasting pans:



The picture was taken in complete darkness, and the burners were not hot enough to glow visible red, but the camera could see them in the near infrared.

Unfortunately, this doesn't make it a very useful thermal imager. It can only see the very near infrared, so things have to be 700 degrees or so to show up. It can't even see the heat of the oven walls---it only sees reflected infrared from the coils, not the lower-frequency infrared from the oven walls themselves. (And there's no way plastic is going to show up before it melts.) So far, it hasn't shown me anything I can't see by turning the burners up enough to glow red, and looking at the red glow by eye.
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jegner
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PostPosted: Fri Jan 05, 2007 3:51 pm    Post subject: Reply with quote

That shape might heat more evenly, I don't know. I for one would try it, and if not, remove the thermal probe and tweak it like you did with your first one.

Good luck, and keep us posted!
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fuji0010



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PostPosted: Wed Apr 29, 2009 7:25 am    Post subject: Reply with quote

These Sunbeam Goldline Stainless Steel gas grill burners are exact replacements ... gas grill burners are exact replacements for over 80% of the Sunbeam gas grills ... Includes flexible and fixed venturi tubes. Size: 18 3/4 X 4 inches.

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floridamary4



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PostPosted: Wed Jun 23, 2010 10:17 am    Post subject: re: Reply with quote

thanks for posting Smile
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radnd838
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PostPosted: Wed Feb 23, 2011 4:00 pm    Post subject: Reply with quote

This is great! I'm thankful your posting this information. I will have to check out Walmart for the grill!
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panhandle_shovelheadrider
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PostPosted: Thu Feb 24, 2011 12:50 pm    Post subject: I do that in my powder coating oven Reply with quote

it shields where I want it
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