Welding advise needed!

[Broman]

I have started attaching the thin wire harness tabs (see previous thread) to the new floors of my 71 Z.  And I am not too bold to admit my welding can suck sometimes.

The repro harness tabs are intended to plug weld, so a standard plug weld was what I gave them. Now I can do a reasonable plug weld, but with these I am getting almost zero penetration into the thicker metal off.  After welding all 7 down to the driver side floor, 6 easily popped off with a slight tug.  I have the welder heat set to 2 (out of 4), which is how I normally weld the 18 gauge sheet steel.  This setting has always provided me with good penetration.  So I tried heat setting 3 and it unsurprisingly blew the end of the tab off!

So I am looking for some guidance from people with experiencing plug welding 22 gauge (0.7) mm sheet to 18 gauge.

ARRGGHH....I am ready to just glue these with some 3M panel bond!

[jonbill]

You could run the wire faster on setting 3.  or slower on setting 2.

[dutchzcarguy]

5 hours ago, Broman said:

So I tried heat setting 3 and it unsurprisingly blew the end of the tab off!

Hi, If you don't have enough penatration you need to go from step 2 to step3 but weld just for 1 second at the time.. lay small welds after each other.

Normally when you weld thick steel you can weld for say a minute, but thin steel you have to make small short welds..

Also, welding is putting a current through your cables and the steel your welding..

You have to keep in mind that if you have the earth clamp further from your welding work, that welding current also has to travel further and that extra resistance also reduces the welding current, so the shorter you are on your weld with the earth clamp, the higher the current will be. .. by placing it as far away as possible you create a kind of step 2.5 on your welding machine.  Just be sure that your clamp is making good contact to your chassis.

 

Make small welds and as far as possible from each other, especially when doing something like this door i repaired.. one weld left one to the right then one in the middle.. let it cool down, and weld one left one right, let it cool down and lay some weld between.. cooling down can be done with a damp cloth. (Not to wet. but not to dry 😉 ) 

To be a good welder takes years, it's a matter of trail and error!  Once you understand how it works you get better and better in it!

[inline6]

23 hours ago, Broman said:

I have started attaching the thin wire harness tabs (see previous thread) to the new floors of my 71 Z.  And I am not too bold to admit my welding can suck sometimes.

The repro harness tabs are intended to plug weld, so a standard plug weld was what I gave them. Now I can do a reasonable plug weld, but with these I am getting almost zero penetration into the thicker metal off.  After welding all 7 down to the driver side floor, 6 easily popped off with a slight tug.  I have the welder heat set to 2 (out of 4), which is how I normally weld the 18 gauge sheet steel.  This setting has always provided me with good penetration.  So I tried heat setting 3 and it unsurprisingly blew the end of the tab off!

So I am looking for some guidance from people with experiencing plug welding 22 gauge (0.7) mm sheet to 18 gauge.

ARRGGHH....I am ready to just glue these with some 3M panel bond!

The tab thickness is .7 mm or .028"?  What is the thickness of the panel?  

You are getting nearly zero penetration into the panel to which you are attaching the tabs?  What is your wire speed?  Is the panel prepped to bare metal where you are attempting to attach the tabs?  Are you starting in the center of the hole, on the panel, or at the edge of the hole in the tab?

Do the former, not the latter.  Trigger, and then stay in the center of the hole in the tab - on the panel only, as if just trying to put a blob of weld on the panel portion.  As that builds, you can move out out of the center of the hole and "pick up" the edge of the tab.  When you do, the tab metal will melt (quickly) and pull the "blob" you started in the middle of the hole - the molten metal of what you started on the panel and the molten metal of the tab will join.  Following this technique will maximize time on the thicker panel portion, and should help with penetration on that panel.

Another idea: How big is the diameter of the hole in the tabs? If I still couldn't get good penetration to the panel with the above technique, I'd consider making the hole in the tab larger and repeating the technique above.  Looking at your pic, the holes can be enlarged without making the edges too thin.  

You need to get the panel hot enough first, then slide to the tab which will melt much quicker by comparison.  A larger hole in the tab will allow you to buy time "pre-heating" the panel, which equates to better penetration.  
  

Edited February 2 by inline6

[Broman]

Well, I figured it out.  Dumb mistake.

Based on where the welder need to sit to reach the work area, I had to reach over the top to flip on the power switch.  Seems that when doing so I bumped the feed knob a bit high.  The incoming wire was cooling the area enough that I was not getting good penetration.  I backed the feed speed back to where I wanted it and now my plug welds are solid!