Cant penetrate due to thickness ideas?

[chunkytfg]

Say for arguements sake my clarke 135te can actually butt weld up the the alledged max of 4mm steel.

Now i have a task of welding two 5mm bits together. Now obviously i cant just turn it up max and go for it as there will no way in hell it will work.

what would be difference of welding from both sides getting about 3mm penetration each time verses getting a welder that will actually achieve the necessary penetration for a good weld?

I dont actually have to do this by the way just thinking out loud really

 

[Iain Westland]

max ish from both sides except if its critical in which case its time for a bigger mackine or a stick

 

[chunkytfg]

max ish from both sides except if its critical in which case its time for a bigger mackine or a stick

dont take this the wrong way but ...... huh?

I suppose what i'm asking is if the two lines of weld meet in the middle and penetrate into each other would that be the same as one weld going all the way through?

This is purely hyperthetical as i'm just thinking out loud while trying to teach myself how to weld

 

[hotrodder]

In the case of a butt weld, welding form both sides can actually be helpful with regards to distortion. Bevelling and/or gapping the parts to be welded can also help, in the case of welding from both sides you'd usually grind the back of the first weld before laying the second.

 

[chunkytfg]

Fair enough so it is a perfectly acceptable technique.

good to know i'm not coming up with totally bonkers ideas!

 

[weldingscotty803]

helps if you bevel the edges a bit too. leaving a gap also helps, only need around 1mm

 

[malcolm]

Problem with welding metal that is too thick is the penetration drops off rapidly. You might be able to penetrate 3mm sheet, but if you tried 6mm on the same settings chances are you might only penetrate 1 in as the thick metal takes all the heat away.

I'm with weldingscotty - better solution to V the joint and leave a root gap. See the demo here: http://www.mig-welding.co.uk/tutorial.htm

 

[asmeix6g]

dont worry too much about the size of your machine, unless your welding heavy stuff all day dont get a bigger set cuz its a waste of your money.
if you need more penetration grind a V shape into the butt i.e 30 degrees off each face so when butted together your left with a V. I would take it right down to a knife edge or leave a small edge on it and have a gap. that way you can put a good 1st run in and then build it up with other runs over till the V is all filled in, if you get me?
Iv welded extremely critical parts in the pasy which have required a high level of pre heat. but for what you do V it all the way!

 

[Bsmith]

V, 1mm gap and weld vertically up if possible for good penetration.