I've had the pleasure of learning to arc weld from a guy who's been doing it for longer than I've been alive. He is currently the shop foreman at the local county's road and bridge department working on the heavy equipment side.
When arc welding, there are some important guidlines to follow.
1st, hotter/higher amps is not always better. The hotter you go, the more the bead will tend to spread out and cause your bead to run all over without good control. Conversely, if you go too cold, the bead will tend to stack up tall and skinny and not adhere/penetrate well. You also tent to stick the rod to the surface a lot. You have to find a happy medium on the heat. Every machine is different and the heat setting that works on one machine may be as much as ten amps different than the heat setting that works on another machine. This is true even on the same make and model of machine, even from trusted companies like Lincoln and Miller. Running at a hotter setting will result in you chasing your bead because it is running out so quickly. Turn the heat down and you can work the bead the way you want it much easier.
2nd, keep your arc between the end of the rod and the bead as small and consistent as possible. Moving the rod too far out will cause splatter to increase and the penetration to go down. Shorter arcs are almost always better to ensure good penetration.
3rd, read the puddle. This is the part that really takes practice. The end of the rod is just like the sights on a gun, it'll shoot where you point it. You want to be pointing the puddle directly into the seam you are trying to weld. Once you are started and the metal is warming up as you go, you will be able to push the puddle into the seam by moving your rod in closer. It IS possible to run a full-penetration weld smack in the middle of a piece of plate. You are litterally pushing the puddle and the arc all the way through the plate and out the other side. You want to be doing the same thing on your seams.
Practice, practice, practice. The best thing to do is take a piece of 6"x6" 3/16" plate and run beads the full width of the plate in straight lines starting at one side and working your way to the other, quenching and chipping between each bead. Overlap the beads by about 1/3 of their width each time and if you're doing it OK, the overall surface should be reasonably flat. Run beads on one face of the plate 90 degrees off from the other side to keep the plate at flat as possible. Once you have both sides fully covered in beads, rotate 90 degrees and do another layer. By the time I was running smooth beads with 6010, 6013 and 7018 using this method, I had a piece of 3/16 plate covered in about an inch of welding material. To this day, I will still start this way on any machine I've never used before to get myself familiar with it's heat settings and how it works with each type of rod.
Most professional arc welders anymore use 6010 and 7018 almost exclusively. It is very rare to even see a blueprint that calls for 6011 or 6013, but there are some times they are needed.
6010 is a splatter rod and does require you to work the bead more but it is significantly more forgiving than 7018 when you're first learning. You can also achieve much deeper penetration at lower heat settings (I usually run 6010 somewhere between 85-95 on 3/16 depending on the machine).
7018 is a drag rod. It should NEVER be welded downhill, only uphill. The nature of the rod makes it virtually impossible to get appropriate penetration from it going downhill. You have to turn the heat down a bit and allow the bead to build up as you push it uphill. For the beginner, the best this you can do is rotate your surface so it is flat rather than trying to run a vertical weld.
6010 can be run downhill but most pro welders will still run it uphill if they can since it produces a cleaner bead and better penetration uphill.
I hope this helps!
When arc welding, there are some important guidlines to follow.
1st, hotter/higher amps is not always better. The hotter you go, the more the bead will tend to spread out and cause your bead to run all over without good control. Conversely, if you go too cold, the bead will tend to stack up tall and skinny and not adhere/penetrate well. You also tent to stick the rod to the surface a lot. You have to find a happy medium on the heat. Every machine is different and the heat setting that works on one machine may be as much as ten amps different than the heat setting that works on another machine. This is true even on the same make and model of machine, even from trusted companies like Lincoln and Miller. Running at a hotter setting will result in you chasing your bead because it is running out so quickly. Turn the heat down and you can work the bead the way you want it much easier.
2nd, keep your arc between the end of the rod and the bead as small and consistent as possible. Moving the rod too far out will cause splatter to increase and the penetration to go down. Shorter arcs are almost always better to ensure good penetration.
3rd, read the puddle. This is the part that really takes practice. The end of the rod is just like the sights on a gun, it'll shoot where you point it. You want to be pointing the puddle directly into the seam you are trying to weld. Once you are started and the metal is warming up as you go, you will be able to push the puddle into the seam by moving your rod in closer. It IS possible to run a full-penetration weld smack in the middle of a piece of plate. You are litterally pushing the puddle and the arc all the way through the plate and out the other side. You want to be doing the same thing on your seams.
Practice, practice, practice. The best thing to do is take a piece of 6"x6" 3/16" plate and run beads the full width of the plate in straight lines starting at one side and working your way to the other, quenching and chipping between each bead. Overlap the beads by about 1/3 of their width each time and if you're doing it OK, the overall surface should be reasonably flat. Run beads on one face of the plate 90 degrees off from the other side to keep the plate at flat as possible. Once you have both sides fully covered in beads, rotate 90 degrees and do another layer. By the time I was running smooth beads with 6010, 6013 and 7018 using this method, I had a piece of 3/16 plate covered in about an inch of welding material. To this day, I will still start this way on any machine I've never used before to get myself familiar with it's heat settings and how it works with each type of rod.
Most professional arc welders anymore use 6010 and 7018 almost exclusively. It is very rare to even see a blueprint that calls for 6011 or 6013, but there are some times they are needed.
6010 is a splatter rod and does require you to work the bead more but it is significantly more forgiving than 7018 when you're first learning. You can also achieve much deeper penetration at lower heat settings (I usually run 6010 somewhere between 85-95 on 3/16 depending on the machine).
7018 is a drag rod. It should NEVER be welded downhill, only uphill. The nature of the rod makes it virtually impossible to get appropriate penetration from it going downhill. You have to turn the heat down a bit and allow the bead to build up as you push it uphill. For the beginner, the best this you can do is rotate your surface so it is flat rather than trying to run a vertical weld.
6010 can be run downhill but most pro welders will still run it uphill if they can since it produces a cleaner bead and better penetration uphill.
I hope this helps!