Since many here want to install conduit in their workshops, I thought I'd get a conduit bending workshop going here. The only damage you can do is too the pipe, and maybe your ego. Of course, you need to have designed the system correctly. We can do that in another thread, if there's an interest in it.
From left to right - 1" EMT (or 3/4" GRC), 3/4" EMT (1/2" GRC), 1/2" EMT and 1/2" EMT short radius bender. The two on the left are made by Benfield, the best but they are out of business now. The blue handled one is made by Ideal and the brand most seen on jobsites around here now. The short radius bender is made by Lew Fittings in Chicago but I think they are OOB too. Many municipalities outlawed short radius bends because they make wire pulling so much harder and that could put a strain on the insulation. But there are times when the short radius bend is needed, just make sure it's the only bend in a run and the pipe run is short, if possible. Two short radius bends in the same run will have you yelling at yourself for not heeding my warning.
I've used benders by Gardner-Bender, Greenlee, Klein and a bunch of other brands I'd prefer to forget. If you can find an Ideal bender, buy it. If you find a Benfield at a flea market or something, grab it, immediately! They are the best. Good marks and very accurate. But whatever you do, don't buy one of those 1/2" & 3/4" combos. They will make you hate bending pipe. And forget the built in levels, they are a gimmick. Buy a good level (see below).
A good bender has an arrow and a star marker on it, and graduated degree markings. There is also an indentation in the channel but we'll get to that later.
We're going to start with a simple 10" 90 degree bend on 1/2" EMT. On all benders you have what is called a take-up. It's a number subtracted from whatever length 90 you want to make, when using the arrow on the bender. 1/2" benders have a 5" take-up, 3/4" - 6" TU, 1" - 8" TU. They are usually marked on the bender shoe.
For a 10" 90, I made a pencil mark at 5" - 10-5=5. I use pencil because it's harder to see once the pipe is installed. Felt marks all over your work is very unprofessional looking. IMHO
Take that pencil mark you made at 5" and place it at the center of the arrow mark on the bender. The take-up deduction is only used when using the arrow mark on the bender. The star we'll talk about later.
The first thing you have to do is apply a good amount of foot pressure on the heel of the bender. If you don't do this, the pipe might kink and almost certainly throw your bend off. You can get an idea how much pressure I'm applying by the indentation in my gym shoe sole and the fact the heel on my other shoe is coming off the ground (gym shoes aren't recommended for pipe bending because the sole is too soft but they work OK for 1/2"). While keeping foot pressure on the heel, begin to pull the handle back. This is done all at once but only for 15-30 degrees at a time. This is the most critical time for keeping good foot pressure on the bender heel. Think of your foot pressure as making the bend and the handle a guiding the bender.
Sorry for the blurry picture The bender handle is now perpendicular with the ground. (Keep this in mind, it will help with offsets when we get to that later on.) While you're making the bend, do the bending incrementally. Press you foot down hard on the heel while pulling the handle back. Do this in short bursts, making sure you don't loose foot pressure on the heel. DON"T TRY TO MAKE THE 90 IN ONE MOTION! That's how pipe kinks happen. As you get better, you'll get the hang of how much to bend per shot.
The 90 is now 10" long, when measured from THE BACK of the bend. Keep this in mind when taking your measurements. If you have a box on the wall and you want to turn the corner with a 90, measure from the side of the box to the wall, subtract for the hanger you'll be using and then subtract the take-up and mark that on your pipe. Then line the mark up with the arrow.
Look, ma, no kinks! If you want a perfect 90, place a level on the floor and see where it reads, then place the level on the 90.
FOOT PRESSURE! FOOT PRESSURE! FOOT PRESSURE! I can't emphasize this more! It's the one part of bending most beginners fail to do. Overdo it initially until you get the hang on how much is needed. The handle is only there to aid the bending your foot is doing. And make all your bends in segments, like 10-30 degrees at a time. The bigger the pipe, the more foot pressure and the more bending segments are needed. I've bent 1-1/4" with a hand bender and it probably takes me 10-15 segments to complete a 90. I practically stomp on the heel while pulling the handle back. It requires all my weight. I am completely off the floor. Even big guys I've worked with have to put most of their weight on the heel with 1-1/4" EMT.
It might not be a bad idea to use a level until you get good at it. And if you want a really professional looking job and don't have a level built into your eyes, a level is a must. This is a nice little level from Greenlee. It does it all.
That thumbscrew is used for making offsets when you don't want a dog in the offset. We'll get to offsets in another post. And yes, I am holding that out into the air and failing to make it read level. But anytime you want to make sure you've bent a perfect 90 or 45 or 30, you need to first make sure the pipe laying horizontal is level, then check the bend.
I think I covered a 90 degree bend completely. Any questions, just ask.