What works on paper, doesn't always work in the physical world as planned, for a variety of reasons. What follows here are some of the various lessons I have learned while laying out sheet metal projects. Hopefully you can benefit from this guide and save yourself the time I spent learning things the hard way!

Step 1: Sheet Metal Has Thickness

When you're making something out of paper, the thickness of the sheet is negligible--everything will line up and work out most likely in the end. Sheet metal is a different creature in this respect. Bends have radius, sheet has thickness, and tools need space to access a bend. When laying out a simple box with tabs, the tabs will meet the perpendicular face of the next side when folded up to 90 degrees, so when you are folding your tabs, measure in from the edge of the material the length of the tab, plus the radius of the bend, plus the thickness of the material for a perfect corner.

When folding over a seamed edge, the folded-over portion is going to need to clear the adjacent faces on both sides. Slightly notching these helps resolve these issues. A file is sufficient for fine-tuning these bends.

Think of bending sheet metal as what it really is: stretching one face, while shrinking the opposite face in a controlled way.


Ive been a sheet metal worker for close to 20 years now. Went from old school techniques to modern equipment. This is a GREAT instructable. Very well done.
Hi iwant to make a small working boat model with thin sheet metal can i glue it with araldite or is there any way to make joint watertight without welding or rivets
<p>I am not familiar with araldite, but you could do a grooved flat lock seam and silicone it from the inside. If you're trying to make the keel joint where the two hulls meet, you may be able to form this from a single sheet rather than seaming it. </p><p>Forming By Raising: </p><p>Heat it to anneal the sheet. Use a blunt v-shaped die over a wooden form or sandbag to begin to stretch a ridge in the sheet. Anneal often. Use a ball peen hammer and work out from the keel and up the hulls and raise the radius into the sides. Trim flush with a pair of snips and clean up on a disc sander. Copper would work best, and you'll want the sheet to be a little thicker than your finished piece. </p><p>Rotary Seaming:</p><p>You could roll a hem on a rotary machine. That's how soda cans are made (kind of) and they're water tight. </p><p>Box Break:</p><p>You could also form a keel seem from a 90-120 degree bend on a sheet break. Draw the arc you want for the hull, transfer it to both sides, Cut away the excess on one side, cut away all but a 1/4&quot; tab on the other side, then epoxy the tab to the opposite side. Silicone the inside. </p><p>That said, you could also just learn to solder. It's way easier than forming sheet stock manually like this. Happy tinkering!</p>
I wouldn't even try to weld galvanized metal, unless you want zinc poisoning haha.
pretty cool Bro , I learned more than a few things , well done man !
A thick Sharpie line before you scribe can help make the scribe line much more visible, though, and you can use different colours for bend, cut, etc. Excellent instructable, thanks!
Great instructable! Watchoutn when using HF hand seamer, I squeezed mine a too tight and broke it in half. I kept the bits to make a sand casting with in order to make a real Made in America tool in my home founfry.
Thanks! Most HF tools leave a lot to be desired in terms of durability. I'd love to barter for a home-cast hand seamer if you're casting some!
Very nice instructible, brought me back to a better day. As does just thinking about the glorious sheets of 060 stainless steel (with the edges so dul, gloves were merely a fashion statement) and 12 foot skids of clad and unclad aluminum stacked 15 + feet high, with brown paper sandwiched betwixt every sheet. Oh yes, those were the good old days and now that you've mentioned it, there's no reason they can't be relived a bit for old timer's sake. Thank you for this. One question; I've a pair of straight tin snips that need to be sharpened and perhaps tightened up, what type of edge should they have and how tight should they be etc. I think you are the person to ask. (if the good old days were still here I'd have a brand new pair)
My shears all have a single bevel edge that I touch up with files. I'm not sure of the angle. As for the tightness of the shear, there are many styles with their own specific tightnesses. My recommendation would be to pick up a set of thickness gauges like machinists use. Slide them into the joint on a pair that feels good to you and adjust accordingly. Happy metal working!
While this is a great instructables, there's two small thing I could suggest to help you improve it.<br><br>1. The scratch awl is a good idea to precisely trace a flat pattern on sheet metal, BUT I would not recommend using this method for any &quot;structural&quot; component. The reason is simple, you are adding weak spots all over the place,and they will sooner or later result in fractures.<br><br>2. You probably did this for the convenience of it when cutting your metal, but the &quot;sharp corners&quot; on your flange near the bending lines are also weak spots waiting to transform in fractures. You can easily drill a small hole in those corners before cutting the metal with your snip to create small radiuses that will help increase toughness.
looks like the engineer's toolbox (i know its not, its an older design of a toolbox)
Excellent instructable, truly
Thank you for a very fine, useful Instructable. I am thankful to have a welder, but find there are times when my pop rivet gun is the better choice. As regards &quot;free&quot; metal, we recently replaced a water heater. The old one is full of lime and heavy. I am cutting it up in pieces before trying to haul it up the basement stairs. The outer shell is a nice gauge of sheet steel I want to use for various projects, including some small parts trays. I hope your Instructable is featured and makes the newsletter.
Thanks! To make that outer shell lay flat, you can &quot;cross break&quot; the sheet using a break press. Make an X across the sheet, then a box around the perimeter and it will lay flat.
Nice intro into becoming a diy tin knocker, thanks.<br>I have been thinking about making a small brake and trying my hand at it.
If you just want to get a feel for sheet metal without a huge investment, there are tool called &quot;bar folders&quot; which are basically a hinge that bolts to a surface with a machined-flat piece of bar stock that you clamp over the material you want to bend. Bend the piece up to the desired angle. Harbor Freight has one for $40: http://www.harborfreight.com/18-inch-bending-brake-39103.html
This is a great intro to working with sheet metal! I learned a ton.

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Bio: I'm a compulsively curious guy. I have taken things apart all my life, intrigued by how things work. I didn't know other tinkerers ... More »
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