In your QUESTION you say you are using "3/16" rods......
I hope you meant a "3/32" inch rods which would be the rod to use on 1/8th plate.
A rod larger than a 1/8th rod for your welder is going to be dificult....you would need a larger welder. 3/16 is 1/3 larger than a 1/8th rod. "Using a "cracker box" welder" you should just use 1/16 rod....or 3/32 or a 1/8th rod and your welds and they will look fine.
Look.... there is the difference in welding rods.
The first two numbers are the type of metal of the rod.
1. 60xx = 60,000 tensile strength rod (mild steel)
2. 70xx = 70,K tensile strength rod (low hydrogen steel)
The last two numbers are the Position of the weld.
1. xx10 for welding over your head (colder weld)
2. xx11 for vertical welding
3. xx11IP 11+ iron power is for hard steal and quick filler
and use on high tensile steel, to replace the lost iron in
welding....and makes a good cover
4. xx13 Is for welding flat plate at a high rate and general
welding and repair
5. xx18 only for flat smooth fast welding, xxx18 rods are for
surfacing and smooth welding as it will have no ripples if
done correctly. These welds are usually to machine parts
and for grinding and polishing smooth.
Example: 7018 70 = higher tensile strength (70) called "low hydrogen" fill metals.....Then 18 = flat machinable weld.
(If you have a weld that is going to paint and be seen use this rod and it will look like smoothed butter.
Example: 6013 = 60K metal mild steel and (13) Flat position welding is its purpose. (but it is a general welding rod!)
Example: 6011"IP" or a iron powder additive in the flux.
You would use this rod on trailer hitches and motor mounts things you do not want to break that has a lot of stress.
As welding weakens metal sometimes, the Iron Powder replaces the iron lost and makes a stiff strong weld.
There are many rods up to 110xx rods but unless your a pipeline welder on exotic metals you will probably never need one....but there are many special application rods, you need to know that.....in case you have a problem in the future.
Welding" if you have two pieces of metal with square edges you would weld in lenier fashion. That is you will move your stick back and forth in a straight line.....preheating the metal in your path for a smooth weld.
Welding" If you have a inside angle weld, or beveled plates with clearance for true thru welding......you will use a circular welding motion ....heating up the sides of the welds, if the area becomes too "red" expand your circle a little. That will allow your rod to "clean" itself so when you get back in the weld "puddle" it will be even with flux. The side flux will burn off a bit then make your circle to clean it up and pre-heat the next area to weld again.
makes a weld like " (((((((((((((((((((((O).
If your moving your rod too fast the weld will look like this,
If you have a high stress area and have a "))))))))))))))))(O)" weld then you would weld over this weld in a figure 8 fashion heating greatly each side to a real "red" weld spot.
This is called lacing and will "stress relieve" the brittle weld area and increase the strength of weld. Used on very high pressure pipe (steam or natural gas pipe application.)
Your weld will look like this 888888888888888888888(o).
Its like lacing a boot....and you may need to know that one day...if you get stuck with a broken weld repair.
The heat to use....you can figure it out I'm sure....
if its not hot enough.......it won't work.
"Combination welds" (dirty metal) use a 6010 or 11 and burn a "root bead" which will not fill up the area.....Then top it with a 6013 rod to weld on top of the 6011 weld to a smooth professional look......which I am sure you can do NOW!!!!
Print this out and stick it on a bench for a while....just to remind you....after you throw your gloves out the door and walk off a couple of times.......when you come back you might want to read this again......lol !
Your 1/8 tubing is a piece of cake, grind it smooth and cook on some 6013.....and go have a coke, and look at it for a while.....its sure is pretty when you get it right!