How do I measure the gauge of sheet metal... for example, what would be the gauge of the sheet metal sides in a fridge or washer or dryer?
I am in a remote location and do not have access to a sheet metal shop. I need to make a guard for the pulleys and belt on a woodworking machine. I need to make two simple 90 degree bends. Is the metal in a washing machine side too heavy to bend in a home made jig?
Hmmmm... your message does leave out a lot of your requirements, capabilities and available equipment. You also don't give even a rough idea as to the dimensions and type of bends you think you need. I this for a home-shop, or something more commercial where you might see an inspector looking at it?
I don't have a spare dryer or what-ever to measure the thickness, but I guess they would be somewhere in the neighbourhood of 22 to 18 gage.
If you need a guard heavy enough to stand on, then washing machine sides are too light. If you merely want to keep a bit of sawdust or wood scraps from falling into the belts/pulleys, then it should do very nicely, maybe even be a bit heavier than needed, depending on sizes. What capability do you have to cut a washing machine panel into the sizes you need? Could you cut and fabricate, rather than cut and bend? In other words, make a "side", and then a "top" and fasten the two together with angle brackets and screws to fabricate a guard?
What "angle" were you considering bending to? 90 degrees, with a sharp corner, say 24" long, is not do-able without a brake. On the other hand, you might get a sort of curvy edged 90 by clamping with hinged plywood slabs with the sheet metal clamped to them.
Not knowing what you really want/need, I've seen some very nice guards just made with wood, and plywood or even "paneling". Painted up, it is hard to tell it isn't sheet steel. Fibreglassed, it's perfect, and if you've got real expertise with FG, then it can be layed-up into a mold to suit any manner of contortions.
I don't know the gauge of the sheet metal in a washer or dryer, but I have made 90 degree bends in heavier material. My method is to use some 2 inch by 2 inch or bigger angle iron as vise jaw extensions. Then use a couple of C clamps out at the ends to help clamp the metal tight. Then it just a matter of pushing on it and beating on it with a mallet ( or hammer ). I hope you have a good vise. In addition to the eye pretection mentioned, ear protection is good too.
Appliance skins are pretty thin. I just measured some I took off a water heater (years ago) to be .021 which would be about 26 gage after the paint was stripped. I'd guess washing machines might be 24 gage which is .025". Sheet steel like this is not difficult to bend.
Aside: Of that whole water heater skin, I only have about a 12" x 18" piece left. The rest of it got welded into various kid's beaters as rust repairs over the years. Had one Aspen that I swear pulled to the right when it passed a Minnegasco installation.....
Anyay, you can make a jig to do this out of hardwood since you probably have that at hand. Just clamp the metal between two stout pieces of hardwood, and then begin bending it with another piece of hardwood used as a drift and placed very near the desired bend with a mallet. The idea there is to confine the bending to around the corner of the underlying support rather than bending the "flying" metal. Just walk along the bend, bending a little bit with each blow, then go back and repeat. When the metal gets bent reasonably close to desired angle for the whole length, then go along with your mallet and pound the bent part flat against the underlying hardwood. Many light blows work much better than a few heavy blows. You can't avoid a little distortion, but if you keep it minimal then it's easy to hammer the metal back flat when the bend is nearly complete.
This is hardly a "production" technique, but it works quite well for a one-off if you're not working with critical dimensions and are patient. It is amazing what a person skilled with a hammer can do with sheet steel, some bits of hardwood and a shot bag. I'm not one of those, but making bends in thin metal is really quite easy.
Water heaters are painted, but I believe that most washing machines and dryers have a thin porcelain coating (sort of a white or pastel colored glass) -- which will fragment at the site of any bend, and send sharp pieces flying. As has already been suggested in other followups to the same question posted a bit ago, you really need to be sure that you have safety glasses on -- and anyone who happens to be watching you needs them as well.
Anyway -- other than that, it is not that difficult to bend, and you have gotten good advice on that -- but it will really be *ugly* when it is done, with all of those flakes out of the finish.
The beat-it-over-an-edge-with-a-rubber-hammer technique others have described has worked for me on 0.060 stainless steel, which is much harder to bend than scrap appliance panels.
I make belt guards out of wire fencing which is quite a bit easier to form than sheet steel, especially the curves. It can be lined with 1/4" hardware cloth to keep fingers out and framed with angle or strap iron for strength. If you mark the key slot location on the pulley you can easily see if the setscrew has loosened and the pulley is starting to shift.
Expanded metal was what we commonly used for guards for woodwoorking machinery in areas which didn't need to be sealed against dust buildup. The primary reason was to be able to blow out all the sawdust without having to remove the guard each time you cleaned-up.
Dan's method is the standard for those of us who don't have a bending brake.
The mallet/rubber hammer method works for thicker material but will leave marks on thinner stuff if you're not very careful. I usually use metal hammers to strike a 2x4 to make the bend. It spreads the blow. Don't try to make the whole bend at once. The first pass along the length of the work might only bend about 5 degrees. The next pass might add 10 degrees to that. In most cases it takes 5 or 6 passes to complete the bend. More passes are better since it gives you more chances to correct any mistakes. The prettier you want the result to be the more passes are needed.