Camp griddle

Click on the pictures to see a larger view

Here is the griddle that I made for camping. By camping I don't mean backpack camping. This griddle weighs close to 50lbs. I definitely wouldn't be hiking far carrying it.
The top is 1/2" steel plate. The sides are 1/8"x6" flat stock.

The cooking surface is 24"x15". There's no special reason for this size other than I had a some left over plate that was 15" wide. 24" long seemed reasonable.
There's a drain hole at the back right of the plate. This was tapped from the underside for 1/8" NPT threads. A small brass fitting was screwed into the hole. The hole lets extra grease run off and the brass fitting makes the grease drip cleanly away from the plate rather than run all along the underside of the plate

I used a regular propane grill replacement regulator. I bought this at Lowes. I don't know what pressure this puts out, but there's no adjustment

The burners are made from 1" black pipe (again because I had some scraps laying around. Do you see a pattern forming?). The front side of the burners (facing up in this picture) are just slip fit in a hole in the front. The backside of the burners are bolted to the back. I made these removeable so I can build new burners if these ever rust out. I originally intended to put some sort of guide plates on the back to ensure the burners couldn't twist. That's why the burner ends have that rectangular plate on them. As it turns out, a single bolt holds them fine. Just make sure they're twisted into the correct position when you tighten the bolt

The holes in the burner are 5/64". I can hear you say "That's an odd size". Yes it is. I originally was going to drill them 1/16, but I broke the bit after just a few holes. The next size up in my drill case.... yep 5/64ths. There's no special reason for this hole size. I didn't have a clue what size would work well. I just reasoned, I can drill a small hole and if it doesn't work well I can always redrill a larger hole. Ends up the 5/64th hole works well. A hole a little bigger or small would probably work just as well. There are two rows of holes 90 degrees apart on the pipe. The holes are close enough together the flame will run to all holes when lit. Notice near the front, there's a set of holes going over the top to carry the flame from one side to the other
The front end of the burner (to the right in the picture) has a 1"-to-3/4" reducer and a 3/4"x2" nipple on the end. This gives just a little bit of a venturi around the gas jet. You want to keep your burner holes a few inches away from the jet. This gives the gas and air time to swirl around and get mixed together well before it goes out the hole to get burned. Make the holes too close to the jet and they'll burn erradically.

This is the back end of the burner. There is a nut welded inside the rectangular plate. The inside end of the nut is made airtight by filling over it with weld. The nut is fully welded to the plate and the plate is fully welded to the end of the tube making everything airtight.

The jet is made from 1/4" copper tubing. I cut a short length of tubing and put it in the clamp that goes with my tubing flaring tool. I didn't use the flaring die on it though. Instead I took a round blunt nose punch and went around the tube lightly tapping the punch with a hammer. This makes the end of the tube roll over and close off the tube. After I had the end of the tube well sealed off, I filed a flat spot across the end. Then I took a #70 drill bit and drilled the jet hole.
It took a little experimenting to figure out that a #70 hole worked well. The size you need will depend on the pressure from your regulator, your altitude, and probably a whole lot of other things. I'd recommend starting with a small bit and working your way up. Keep testing each size along the way. Remember if you mess up and drill it oversized, don't worry. You can just take the punch, beat the end closed, and start over.
The back end of the jet has a compression fitting that matches my valves

This is a flint striker that's made for colman lanterns. I didn't want to have to worry about keeping matches around to light the griddle. So I used one of these strikers. I got this one at Wal-Mart

Here's the view of the first burner. Notice the knob on the right side. This is the striker. Turn on the gas, give this knob a quick spin flick, and the burner lights up. Just turn the gas on the 2nd burner after you've lit the first. In a few seconds the gas will reach the 1st burner and flame will jump across. There's no big pop when this happens. Sometimes you can't even hear it. You have to light the burners across in sequence. You can turn off any burner you don't want after they are all lit

With the small holes and the close spacing the burners put out good flames. You'll notice all the extra holes around the outside of the griddle. These are vents and they are absolutely necessary! I first tried the burners with just a few vent holes. The burners worked fine for 10 or 15 seconds, but the flame would start dancing up away from the burner holes. If you left them on longer eventually the flame would move down to the very bottom (below the burners). Without enough venting there is no more oxygen coming in. I incorrectly thought all of the oxygen you need would come through the venturi. This doesn't appear to be the case. With enough venting the burners work fine

Since the plate is steel and not cast iron like some of the old griddles, you can throw water on it without worrying about it cracking. This makes an easy way to clean up. Throw a little water on it. Let it boil and soften any gunk. Then scrape the griddle and push the water down the drain hole with a metal spatula.
There are a few things I would do differently if I were building another griddle.
The burners are too close to the plate. The flames are touching the underside of the plate. This causes incomplete combustion and some sooting of the plate. Another inch of clearance would probably solve the problem.

The griddle top has a 1/2"x1/8" flat stock trim piece that is welded around the outside. This keeps the grease from running over the edge. The griddle has one welded pass around the plate to attach the plate to the lower box. Then it has another welded pass around the plate to attach the trim piece. There's no reason why you can't just recess the plate down in the lower box to get this lip. This lets you make only one welded pass.

The burners are a little far apart (6 inches). When you plug the drain hole and fill the top with water. The water will only boil in strips directly over the burners. When cooking this isn't so much of an issue. Without a covering of water you aren't sucking heat out of the plate as fast. This lets the heat distribute itself down the plate more evenly. I would probably built another griddle of this size using 5 burners

A stainless griddle would be nice, but very expensive. The mild steel plate will rust. Just be sure to wipe a little vegatable oil over it after you've washed and dried it.

Also see the deep fryer and single burner stove I built.