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Frame Design and Construction
Nice work! s:2 s:1

I'll see if I can fit that into the sheets that I have.

Nonferrous for front and back, eh?
Does that mean that we might have to use brass?? B) c:2
Well, the front could be brass, but just aluminum would work fine. And the back actually doesn't matter. I guess I just grouped them together. Back can be anything.

Based on that list, do you have enough for the cooler?
I have playing with the layout of these parts on the 4 four pieces of stainless steel that I have. The pieces are 14x72, 24x72, 24x48 and 24x48. I got all of the pieces arranged so that they could be cut out, with three exceptions.
I'm thinking that I'd like to go with aluminum for the chaff tray [#8 & #9] and use brass for the front [#10].

Here is what I have come up with:
David attached the following image:
Hey, it looks like we are finally starting to get somewhere. Nice layout.

Commentary now.

Making the dividers out of SS (3 & 4) is a bit overkill, but since you have the material I don't have any real problem with it.

Brass will be sharp looking for the front and should be easy to work.

OTOH, using this SS for the inner roasting chamber (5, 6 & 7) I think is just asking for trouble. We need to do a bit of fussy exacting cuts and joins and I worry the stainless is just not going to allow that with the basic tools we have. Personally I would prefer aluminum or mild steel. And just as a gut feeling, I would prefer the entire chamber be one material, and the bottom you have opted for aluminum, so that would be my choice. Leave the pretty stainless for where it will show.

On a flip side, if you want to give it a go, it was free material and maybe it won't be as bad as I expect.

At this point it looks like you have enough for the cooling tray portion and we can test SS there.

Are you ready to give it a go?
Well, I have been thinking about this stainless steel that I have. It would look so nice as an outer skin and yet a PITA to try to build some of the more complex stuff with. If I just used it to skin the roaster, I could have enough for two roasters: one for me and one, umm, for you!

I laid out the pieces that I thought we'd need to do the outer parts and there is just barely enough [see diagram]. We might be" forced" to use the brass for the front and there would be areas that we would probably want to paint. The top surface of the cooler would be one and the back of the roaster top would be another.

We could use mild steel for all the parts that weren't stainless.

Whaddaya think?
David attached the following image:
Hey, now we are talking. I like inducements :) That sounds great - thank you.

That sounds like a plan.

OK, lets look at getting the needed aluminum and/or mild steel and we can start construction of the cooler as a test.
I'm thinking that the mild steel will look better than the aluminum, unless we are painting it. What's your preference?



David wrote:
I'm thinking that the mild steel will look better than the aluminum, unless we are painting it. What's your preference?


I completely don't have a preference. Aluminum will resist corrosion more whereas mild steel will not. On the same note, this is going to be in a warm environment, so corrosion (rust) should only be a minor concern. And from a visual stand point, I think it is moot for two reasons.

1) Most of where this material will be is hidden
2) I personally have a had time telling the difference in sheet aluminum and sheet steel.

There you go - your call completely factoring in price (steel will be cheaper), workability (aluminum is softer but both are fine), availability and your own internal muse.
Materials List -- for each roaster (assuming Aluminum)

1 14"x42" Item #1
1 12"x56" Item #2
1 12"x60" Item #12

1 18"x18" Item #10

2 16"x14" Items # 3,4
1 12"x30" Item # 5
2 12"x12" Items # 6,7
5 18"x18" Items # 8,9,11, 13, 14

TOTAL 14 pieces

I have the stainless on hand, enough for two roasters..
So, I will order the Brass and Aluminum for two roasters.
I will double the amounts and look for 28 gauge in the Brass and Aluminum

But first, how much additional metal will we need for the ducting?
David attached the following image:

Edited by David on 01/11/2008 11:10 AM


David wrote:
Materials List -- for each roaster (assuming Aluminum)

I have the stainless on hand, enough for two roasters..
So, I will order the Brass and Aluminum for two roasters.
I will double the amounts and look for 28 gauge in the Brass and Aluminum

But first, how much additional metal will we need for the ducting?

Two huh - thank you again.

I actually don't know exactly how much we will need for the ducts. I will have to piece it together. If you can give me over the weekend that would be great. A SWAG (silly wild ass guess) would be a 12" x 24" piece should be more than enough.

Also, the brass need not necessarily be 28 gauge. It could be thicker if need be. It will not be folded, only drilled and cut, and brass is pretty soft.

Also, please keep in mind two thing. The 28 gauge for the aluminum was an educated guess. Before you go spending money, I would like you to find a small piece and verify it is not too thin. It's the difference in theory and practice. I have some sheet metal I have been bending up. I measured it with a tape measure, and pulled the gauge off a table. I don't know for SURE it is 28. Might be 24 for all I know.

Also, (I like that word) I mentioned somewhere we will be needing other small pieces of aluminum or mild steel and that I was just laying out the major pieces for your stainless. I mostly just want you to be aware you are ever so slightly attempting to jump ahead of how I do things. I totally design, then start buying things. I find I get just what I need that way. But I think this is not a bad way either. Keeps the project moving.
OK, I finally went by my local metal shop and spec'ed out metal. First off, the piece I have been experimenting with was 25-26 gauge. Being as soft as it was, you could go to 22 if you want in mild steel or aluminum. Even the 16 gauge was "workable" in that aluminum. So overall, what I am saying there is that in the softer metals my concerns (whether I voiced them or not) were pretty unfounded. And even, the 28 number we/I have been batting around might even be a little light, although folding the edge will be quite easy and that in itself will strengthen the piece.

That all said, report back what you can find. For the bulk pieces above, 24-26 in mild steel or aluminum will work great.

Now, while there I checked out some 20 gauge stainless. Oh man, that stuff may have been free, but you are going to pay for it in the end. Wow that's heavy. I wish you more luck and patience than I had with working SS. That said, you have it, let's move on. It won't impact the project from our viewers standpoint. All the techniques, jigs (which I will design a little heavier) etc, will still apply. The main thing I noted was that unlike the aluminum and mild I looked at, it did not spring. I am not sure of the ramifications of that - merely and observation.

The brass. It is a little harder, but not much, and we don't have much to do with it. We have two approaches we can take on it, mostly for aesthetics. Do you want to go for "rolled" worked edges or just clean cut. For rolled, I would go for 24-26 gauge or so. For clean cut, you could go on up to the 20-22. See what is available. I am good with either. Our only real concern is making sure the magnets on the trier assembly can go through, which leads me to the lighter side again.

Finally, the duct work. Let's go with 26 if you can find it. I had hoped to tell you how much this morning, but I have run out of time. A spare 1' x 2' piece per roaster should do the trick. I will go for a better number a little later, but that is close.
Following your suggestions, I ordered 24 sq ft of mild steel for each of the two roasters we are building.

After checking prices at:;; and

I decided on OnlineMetals. They had 22 gauge for 50% less than MetalExpress; whereas MetalsDepot didn't have as thin as 22 gauge at all. 24 gauge was not available.

I also ordered some angle aluminum for the framework to reach the magic $100 mark that gave me a 10% discount. I selected 72" pieces to be sure they would cover the longest curves of the front and back edges of the roaster frame as well as the rounded upper and lower frame members of the cooler.

$98 for the metals and $12 for the cut fees. Not too bad.
The stunner was the shipping. $57 to get it here from Seattle by UPS. Yoicks! Shock
I guess that's where the value of having a local source comes in, eh?

At any rate, it is ordered and I can start bending it up soon, according to your specifications.


PS> I did not order the thinner metal for the ductwork yet.
Shipping - eh, about what I would expect. Local does make a difference. Especially with gas the way it is lately.

22 should do us pretty well. Plenty heavy enough to work with for structural work, light enough to bend by hand, either free or via a jig. You are welcome to use your break, but I think you may find it won't bend tight enough for what we want and by hand is not so big a deal when using a framing jig to bend around.

Good job! I will start to lay out some of the cooler parts for this and you can get drawing and cutting.
I wanted to put up a few thoughts about how we are going to actually attach and fasten this sweetheart (beast might hurt it's feeling :) ) together.

Generally, for the frame I want to rivet it together. That goes for any piece that should effectively need no maintenance. After that, I am thinking some ilk of sheet metal screws. There are a number of options here and we might as well hash them out.

For the Zen I I used self tapping, hex headed screws. Simple to use, not flush. Not really ugly, but not pretty either.

For this one I am thinking about either flush mounted (we would have to 'tap' recess the sheet metal, but that is not hard - just detail work) screws or forget the flush mount and go for 'nice' raised heads.

Have a look at the drawing. It gives a rough idea of what I mean.

Also, in regards to skinning the roaster, with the frame being riveted together, their will be a gap between the frame and skin. This is no problem, we just have to be aware of it and adjust accordingly (it actually gives us perfect room for flush mounted screws should we want them). And part of the adjustment is the cutting of the skin material. We could calculate how much longer the skin pieces need to be but the much easier and more practical method is to rough cut the skin a little large, drill, bend, fit, and mark where the edges need to go, and then cut it exactly.

I will get some screw photos up at some point. In the meantime, look around and see what strikes your fancy.
Alchemist attached the following image:
Alchemist DIY basic metal work

There are a set of techniques that I have come up with that are based on 'field work'. It is easy to draw something and say, cut that piece 16 1/8" long, drill a centered 1/8" hole 5/16" from the end and a whole nothing thing to do it let along do it with tight enough tolerances for two pieces that need to be fit together while in the your shop with basic hand tools, a tape measure and only two hands.

What it amounts to is the follow philosophy. Design it exactly on paper. Translate those measurements the best you can and as exactly as you can to your initial work (the frame for instance), but then adjust the for your lack of tight tolerances (and accept your lack of tight tolerances as a give - very important) by a piece by piece 'fit, mark, drill, fasten' technique. What you will end up with is something you can actually put together and use as opposed to laying out, marking, and drilling ALL your pieces only to find that three pieces in you were 1/32" off on one (we are doing this free hand you know), and now none of your pieces match up and you are horridly frustrated.

Overall, it is a lesson of 'theory vs practice'.

So, onward. What I am putting together below would effectively be the top, rear corner of the cooling tray frame.
Alchemist attached the following image:
First off, if you don't have a speed square, I can't recommend it enough. Get one.

I generally use a sharp soft pencil to do my marking. It is erasable, thin, and easy to see and will mark most metal surface without damage.

Next, YOU have to decide what side of that line you see you are going to cut on. Blades and lines are not dimensionless things like they are on a drawing. I personally like to cut with the mark just touching/kissing the close edge of my blade. The result is you sometime just see the pencil mark when you are done.

Mostly it is important to just decide and do it. Some people like to cut the mark and align the same bits together, i.e. left side of the blade to the left side of the mark and cut the mark away. I like this sometimes. The main trick is knowing what you plan, and then doing it.
Alchemist attached the following image:

Edited by Alchemist on 07/13/2008 9:49 AM
Mark out your cuts in pencil with your handy dandy speed square.
Alchemist attached the following image:
Next, bend it around your 'jig'. In this case, since it is a 90 degree angle, the 2x4 I am working on is perfect.

And I want you do notice something, and then put it into practice.

Look at the corner of the bend. Perfect 90 degree bends do not exist in the shop. They are tight curves, and take up space. We have to account for that space. How much? Hell if I know, BUT I make test pieces of every new part I make, usually out of scrap and to verify my 'theory vs practice' is working. In this particular case, technically I 'lost'. I did not account for the radius of the bend enough and so the resulting piece binds just a little. Could I use it? Sure. BUT what I can do even more so is LEARN from it, and layout another piece with just a touch more bend radius, and test it again. At some point I will post a picture of my 'test piece' for the Zen I. Modern shop art! Lots of holes, fasteners, all together doing a whole lot of nothing (except teaching me along the way).

As an alternative, we could in this case say "I don't like the bend" and just cut two 45 degree angle parts and attach them via the support (probably with two rivets vs one as I will show in this tutorial). I should mention, I broke my first test piece here because I flexed the aluminum open, and the metal cracked. If that were to happen to you, then instead of wasting the whole piece (with those 25 (26) cuts, we would just cut them clean, go with the flow, and attach them with two rivets independently.
Alchemist attached the following image:
The devil is in the details.

Here is a little more on layout.

First off, note regardless whether you account for the bend radius, you need to layout for the thickness of the part of angle facing down (and out of site). So, even in the 'perfect' world of 90 degree bends, you would lay your lines out 1/8" (the thickness of the metal) this side of the edge (top figure). But, since we are learning from our test pieces, we are also going to NOT have the lines meet up so there is free metal to make that radius. How much? I am sure there are tables (aren't there Dan?) we could look it up in, but I much prefer empirical. Try 1/8", see if it works, and if not, try another at 3/16". Get the idea?

I am going to repeat. One of my goals here is not to hand a design out on a silver platter, but to show how we got there, and then have the design available.
Alchemist attached the following image:
Next, we dry fit our pieces for attachment, and mark (I used sharpie so it would show in the photo - pencil is still fine) the placement of the holes.

Now, BEFORE you drill them out, TEST them out on your 'Shop Art'. Is the hole right for the fastener. Don't assume. TEST IT!!!!!!

And because I had them around, I am using hex head sheet metal screws (non-self tapping as aluminum is so soft), but the same would apply to your rivets.
Alchemist attached the following image:
Now, in a good shop, they have a tool to mark the metal so the drill bit does not wander. I don't have one, but I do have nails.

Get a nail and rap the metal where you want the hole to be. Even a drill press mounted drill can wander, so don't skip this step.

Go ahead and drill both holes (BUT ONLY IN THE OUTER PIECE).
Alchemist attached the following image:
OK, you have both holes drilled. Great. Now dry fit them again.

Mark through ONE (1) of the holes to the support underneath.
Alchemist attached the following image:
Now drill out that one hole (don't for get to tap it with the nail to align the bit).

Since you are 'field aligning' the fit should be perfect.

Fasten the parts together.

At this point you drill straight through the angle part's hole to the support below and be assured of perfect alignment (and don't have to nail tap it this time).
Alchemist attached the following image:
Set that other fastener and you are done with that part.

As with most detailed instructions, it took me probably 10-20 times the time to explain it and you to read it than it does to do it.

Finally, take note of the rounded edge, and how obvious it is that the piece would have fit better if I had had more of a gap in the original speed square laid out piece. Even so, this would fit just fine once all the pieces were together.

One final note I laid out rough dimensions (with exact numbers, I know) but they did not take into account those bend radii. At some point you asked me for the the exact dimensions we would need for the sheet metal skin and I told you I could not answer that. This is exactly why. I didn't (and don't) know how much to allow for bends, and way more importantly the fasteners. The skin will go over those, and you can see how much they are going to add. What we will do is field measure those lengths with some extra, bend the pieces up, fit them, note the overlap (because of the extra), then mark and cut the skin for a perfect fit.
Alchemist attached the following image:
I started practicing some of the metal work fundamentals that you suggested.

On two spare 8" strips of 3/4" angle aluminum I marked off the "V" for the 90 degree bend and drilled the hole at the bottom, as suggested by Dan.

Except for scoring the metal somewhat when drilling the Dan Hole, the cutting on the lines went fairly easily.

Well, the angle wasn't quite right, as will be seen, but that didn't keep it from being easy!
David attached the following image:
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