EDIT: The 3 "sketches" below didn't come out very clearly once I'd compressed the .jpg files to the 256K limit. But it seems that now (since the new Forum software) we can also upload .pdf files. Much better detail than compressed .jpg,s, so I've replaced the original .jpg s with .pdf s. BUT, it seems that you have to click the link shown in order to open the .pdf in a separate screen. SDorry, I'm one of the world's biggest PC klutzes!
See new P.S. at bottom:
START:
Sorry to Dalboy (and anyone else who's been waiting - I very doubt "with bated breath" though!!) for such a long time for my write up on rolling and bending sheet metal. Anyway, FWIW, these are very much my own, often crude method/s.
Also apologies to anyone who was expecting any clever stuff like cute little jigs & tooling. The following is very reminiscent of "Heath Robinson" - as said, its crude even - but I have had a fair bit of success with these methods when fabricating stuff like engine cowlings, aerodynamic fairings, fuel tanks, exhaust pipes, etc, for model aircraft. And in a wide range of sheet metals up to about 2.5 mm or so thick. A further word about material sources is at the end of this post, but generally speaking, thinner is easier.
But I should also say that I DO very much like the look of that little metal rolling machine that someone linked to above (from Cromwell I think), and I believe it incorporates bending bars too. But personally I've never felt the need to invest in such a no doubt excellent little tool (I'm too tight I guess)!
A couple of basic points first:
a) apart from the thickness of the sheet metal (and material type of course), the WIDTH of the bend governs the amount of force required to put a permanent bend (or roll) into sheet metal;
b) if making a right-angle (or close to right angle bend), there should always be a radius to the bend, NOT a sharp crease. A radius of double the thickness of the work is a good working minimum guide IMO;
c) using a simple hammer is NOT a good idea - always hand bend if at all possible, or a simple cobbled-up wooden lever is good if your hands aren't strong enough. But if real force must be used, use a dead-blow hammer if available, or if not, then a heavy mallet (hard rubber ideally).
d) If forced to "hammer", ALWAYS use a piece of hard wood scrap of at least the length of the bend between the face of the mallet/dead-blow and the job. Sharp shocks promote cracks in thin metal and a dead-blow or mallet, plus hard wood "softening", reduces that tendency;
e) "anneal" the metal before bending if you have any doubts, especially if aiming for 90 degree bends (or more). Simply use a broad flame blow lamp, heat the work piece OVERALL to red (-ish) and air cool - NEVER water quench IMO. If the material is ali, cover the whole sheet with a film of damp soap before heating. When the soap turns chocolate brown STOP heating immediately (depending on the exact alloy, it's probably just about to melt!);
f) a lot of metals "work harden" during/after bending. If you have any doubts, stop bending "half way through" and anneal again, as above, before completing the bend;
g) some metals are more "springy" than others (try on a piece of same material scrap first if at all possible). If "springy", then be prepared to bend beyond the angle that you need (adjust the angle of the inner jaw of the jig accordingly, see below), so that when you've finished pushing the bend in, the job "springs back" to the desired angle.
BENDING SHEET & STRIP:
Here's the very crude "bending jig" that I use. Just 2 lengths of hard wood longer than the length of the required bend, a bolt and a captive nut at each end, plus washers of course, does it. With the bolts tightened up, the whole job is held in the vice, so that you can bend by hand, or with lever, or with mallet + hard wood softener assistance if required. The upper rear surface of the jig can be planed to an angle or have a radius planed or routered to suit the required bend radius.
Such a simple jig is hardly worth the name, but it's easy to use. Having marked the job (I use marker pen or crayon, and don't forget to allow for the bend radius), clamp the job in the jig (not too tight). Then clamp the whole lot into the vice so that you're pushing the bend away from you (towards the back of the bench).
The jig can be modified at the rear jaw to allow for the bend radius, or even with a less than/more than 90 degree bend, angled to suit other than right angled bends.
Also shown in the picture are a couple of wooden blanks I made for specific purposes, just to show what's possible - a couple of aircraft fuel tanks, and part of a tuned-length silencer pipe. Such blanks are both simple and useful, along with all the other methods discussed here.
A suitable size steel rod can also be used instead of the bending jig, again longer than the length of the bend in the job. I find piano wire of suitably thick diameter good for this ("music wire" in the USA). This is a good trick for bends that need bigger radii.
But sometimes this can be a three-handed setting up job, so a strip of double-sided carpet tape is useful to get the rod in the correct position against the rear jaw of the vice. And don't forget suitable wooden softening against the serrated front jaw of the vice before tightening up.
Heavy tightening forces aren't necessary, just enough to hold the whole lot completely flat and steady while all the bending action takes place above the vice jaw line.
We'll look at bending other stuff (rods, tubes, etc), in a mo, but first, rolling sheet metal. I use one of 2 methods:
ROLLING SHEET, METHOD A:
View attachment Sheet Metal Rolling - Method A.pdf
This is the simplest method, and very much like rolling cardboard to make up the cut-out trucks and buses and stuff that used to be on the back of Weetabix packets when I was a kid. Surprising perhaps, but this works pretty well with sheet metals too, though for best results the stiffer and thicker sheets (above, say 1.5 mm) usually need to be annealed first.
Just like wood, sheet metal has a grain, though it's usually much harder to see than with wood! The giveaway is the faint lines you may see under a bright light, especially on metals that have been rolled, e.g. tinplate. The trick is to set up the sheet so that you're pulling ALONG the grain.
I looked everywhere to find the "tool holder" I cobbled up years ago to hold the steel rule when using this method, but it seems to be lost, hence the sketch below. As noted on the sketch, I guess a length of small diameter steel wire or rod would do instead of the steel rule but I've never tried that. But the advantage of a rule, with its relatively sharp edge, is that it tends to "crush" the sheet a bit more readily, so needing fewer passes to get the desired diameter roll than I guess a wire-edged rolling tool would. Either way, do make sure that there are no defects whatever along the edge that will contact the job - unwanted dents and buckles again:
View attachment Sketch B.pdf
If possible allow some waste at the end to be pulled, punching or drilling 2 holes there and looping a length of string or something through the holes for a pull handle. Alternatively I use the "tongs" below:
I find this tool rather handy for all sorts of hot and cold uses.
Shown is my nylon-faced dead-blow hammer, plus some 10 thou (inches) half hard brass sheet, just bas an example. More info on material sources below.
ROLLING SHEET, METHOD B
Alternatively, the VERY crude set up shown below also works rather well. I think (hope) the sketch is self-explanatory:
View attachment Sheet metal Rolling - Method B.pdf
Setting up the damp newspapers in rolls is a bit hit & miss, but with some fiddling and trial and error, it works well enough, especially if you're not trying to copy an exact shape (which, from your OP Dalboy, I believe you're not - rather, you need decorative shapes to embellish your wood turning projects, right)?
But in both methods the FLAT sheets of damp newspaper plus a thick layer of polythene on top are ESSENTIAL to give the somewhat resilient base needed for bending "onto". Another good trick for smaller jobs is one of those box wood (now mainly nylon) rollers that are used for wallpaper seams instead of the steel rule.
AND the newspaper and polythene or whatever used must of course be very clean, with no imperfections, specks of grit, etc, present. It's VERY easy to get unwanted bumps, hollows, kinks, dents, etc, into sheet metal - and well-night impossible to get them out again! DAMHIKT!
BENDING OTHER STUFF (wire, tube, etc)
There are various quite neat and cheap little tools available, mainly from specialist model shops, such as the following items (from the LH):
a) Tube Cutter (very similar to the plumbers' tool for copper tubes in central heating, etc, but much smaller);
b) Wire Bending Jig; (you can easily make your own version, bigger if req.);
c) Tube Bending Jig (works well on ali tubes, without wall collapse IF annealed first);
d) Mini Bending Springs, again like plumbers' bending springs, just miniaturised.
This is an odd ball. Years ago, when tills and cash registers were electro-mechanical rather than electronic, I had a mate who serviced and repaired them. He had a lot of special tools, and when one of his benders broke he gave it to me. Used in pairs to "adjust" the length of levers, etc, each tool is (should be!) double-ended, with each end having a different "birds mouth" slot to cater for different thicknesses of strip. Quite handy sometimes, even in its broken form, but very easy to make yourself from MS strip, with different saw cut widths and lengths to cater for different strip thicknesses and widths.
TOOLS & MATERIALS
As already mentioned, specialist model shops that cater for "build-it-yourself" (rather than the "ready to play" variety) of model planes, boats, cars, and especially trains are a good source for some neat special tools such as those shown above.
And these shops usually also stock a range of metals in differing thicknesses from a US company called K&S Metals. I've found brass, copper, tinplate, mild steel, aluminium, and nickel silver (personally I find this last very attractive with its "silvery-brassy" colour).
And you should also find piano wire in meter lengths in differing diameters (gauges - SWG) ranging from 24 or 26 SWG (VERY thin) to about 8 SWG (almost one quarter inch). Brass, copper, and ali tubing in various gauges are also freely available, and K&S Metals specialise in diameters and wall thicknesses which allow one tube to "nest" inside the next size up or down. Quite a useful trick sometimes.
About the only "problem" with the above K&S Metals range of sheets are the standard sizes, which, if memory serves, are about 6 inches x 12 inches. If you need larger sheets than that, plumbers can sometimes help with copper sheet off cuts (though at today's prices you can expect to be making a generous donation in beer tokens!), and if there's an offset printers near you, then used offset print litho plates (which appear to be a pretty tough ali alloy) are a good source too.
There's also a good range of links in the sticky at the top of the General Metalworking section of this Forum. Model engineering suppliers can be very useful for stocking larger sizes of sheet metal, etc, as well as useful small tools.
Finally, if you want to read a bit more about cutting thin sheet without distorting or creasing it, I recommend either a fret/coping saw with fine metal-cutting blade, or, if you can find one, a "Goscut" tool. There's also plenty of info in the net, but to save you going too far from here, and without blowing my own trumpet ('onest Guv!), there's a sticky called "Hacksaws - how to choose 'em, how to use 'em", also at the top of the General Metalworking section here. That's got a lot more info on cutting sheet metal.
I hope all the above helps, and sorry that it took so long to produce but I've had other priorities recently.
AES
Edit for a P.S. Afterthought (applicable mainly to the above "Method B" and with heavier stock). Instead of all the rolled damp newspaper base you can (I believe) use a suitably "massaged" sand bag, which I think is what proper copper smiths use. HTH
