[Merkaba]

when you sing your cords vibrate hundreds of times a second. that creates heat and dries them out more and more. especially if you have poor hydration and nutrition(which most do). over time and especially if youre pushing too hard, you just irritate the lining where the cords meet. its like your cords getting chapped. just like when the moisture on your lips wears away, and they start to peel and chap. its similar. and over time with the continued heat and drier cords they basically become abrasive. im talking microscopic tears here. but collectively it helps to make your cords swell. that means that they arent going to meet together and vibrate properly and the swelling causes pain. this swelling also triggers more mucous in an attempt to protect this raw area. which makes it harder to get a good vibration and tone, which most people try to defeat by pushing harder. then it just snowballs. see the downward spiral. then youre not even strengthening or activating or energizing the cords anymore. just abusing them.
and by all means. when you scream properly there is no pain. think about bands like linkin park, mudvayne, etc, that go on tour and play for an hour or so for four or five times a week, sometimes twice or a time and a half in one day. for like three months at a clip. now when youre first starting out you might get a bit sore afterwards ONLY. and ONLy if youve been training a long while. but you really should never have pain. just stick with that.
lets just say that the rasp should be felt above the adams apple. practice screaming with words that start with H. and try to end them with an H. it helps to open you up. try sounds like Haaah! then HaayyyH. dont try E's yet! it could be dangerous. trust me! now when you go to rasp, that is the one time you have to shift your throat, and not your cords. you slightly close the back of your throat to reflect the air. thats why i always stress practices that allow you to isolate your throat from your vocal muscles. you have to be able to do them independently. its like finding the muscles that blare your nostrils or move your ears. they are there, you just have to isolate them. I like trying to help people because it actually gets my own memory and mind working and helps out. try doing haaahh..and hayyy. im telling you dude, yo should be able to rasp at like 50 percent push. you dont have to push hard to get rasp, you have to be able to stay open and reflect off the throat. its that simple. so practice with easier push so you can relax and get the feel down. and im telling you. if you havent, go get/listen to the original Wonderful World by Louis armstrong. he is rasping and its not his natural voice. he did smoke a ton of weed and have a crunchy voice, but the singing is of the throat. he's hitting it off the back of his throat at like normal singing push. like 20 percent push! now when you go to push more you have to open more which moves the point of reflection a bit, but not that much. its about learning to stay open. then you can bring back the feeling of doing what you did to sing wonderful world and youre done. hehe, its not that easy but its the same thing. dude dont let all of my words and shlt make you think too much. 1. you really should listen to Louis armstrong 2. you should be able to get a scream like rasp and tone at 50 push. 3. relax

thats about the three keys.