i just wanted to know what movement everyone made while they weld like Cs, little Os, or if u just moved it back and forth parellel to what ur welding?
The best is that in the diagram Malcom is pushing the torch yet in the video clip he is pulling the torch. Don't know wether it is right or not but i tend to pull the torch with a sidewards movement in the shape of a "C".
Don
I tend to view torch movement as a freestyle thing.
Pushing forward with a C shape movement seems to be considered reasonable practice for thinish metal. The advantage of that movement for the torurial is it slows the torch travel speed down (most first time welders move the torch too quickly), it spreads the heat away from the joint a little to reduce the chance of blow through, and it makes you arc on both sheets of metal so the joint has a better chance of being sound.
Welding in a circular motion (anyone remember the Donovan song?) is OK - again it reduces the heat in the joint, but lays weld over what you've already done rather than on the sides of the bits you are about to do.
A straight line (no side to side motion) can be effective for a lot of things too, though it's a really bad thing for beginners for all the reasons why a C shaped motion is good.
As migmag says pushing the torch gives deeper penetration and a flatter weld. pulling the torch gives less penetration and a more raised bead. Yesterday i was welding some bits on a transit to get it through the MOT, patch on the sill etc, all that was done using the pull method, to aid not burning holes in it
According to this article on miller's website it's exactly the opposite. Push= less penetration, pull=more. I've just done some more googling and it seems that the miller article is correct . I've always thought it was the same as migmag and Darren say.
This push pull thing, can anyone elaborate on the physics of why the welds differ when pulling or pushing? The confusion of the opposite opinions is making my head spin.
If say pulling for example, then I cannot see why there would be deeper penetration, and would be inclined to think that pushing would cause deeper penetration due to a hotter "focus" on an area with the wire feeding straight into the pool instead of being laid on top of it, so to speak. I am lost obviously.
It's been a few years since I did the course but I recall that it's the opposite of your theory...
'pulling' puts more heat into the weld pool.
Basically, I'd say that as you're forcing more wire into the pool it's taking longer for the pool to spread forwards, you're forcing it to move slower.
When pushing, you're forcing the weld pool to move forwards a bit quicker so less heat build up and less penetration.
Back in the late 80's when I did the course it was referred to as 'leftward' or 'rightward' welding (but this assumes a right-handed person is doing it!).
I thought I read somewhere that the theory behind pushing creating more penetration was the pre-heating effect on the parent metal . I expect the difference is pretty small anyway and I like to push as it gives me a neater weld with less spatter. Still can't find any articles supporting what we thought was correct though, all point to pulling being better.
Didn't notice a great deal of dirrerence when I tried it either, but that was on 1mm sheet. Wondered if the difference would be more noticeable on thick metal.
Noticed quite a big difference to the bead shape and shielding on aluminium though. (Push - on the right - is best for aluminium)
I think where the difference might lie is that when i push, i tend to hold the torch so that it is 10-15 degrees from upright, and when i pull i get lazy and the angle rises to about 25-30 degrees
Ok folks, I've just done some test welds, cut them across the bead and I can confirm that pulling the torch creates taller and narrower welds than pushing and definitely increases penetration! Not by a huge amount but it's a very visible difference.
I've just come across this article on Esab's site which pretty much explains all with photos.
nice little article well worth reading, interesting that 24v seems to give best penetration. And of course the further you stick your tip in the deeper the penetration () on the other hand pulling the tip further away gives less penetration, (need more shrouding gas) but does give a method of controling current when working on car panel stuff.
Needs a custom page malcolm with useful links like this esab one