It has been a week of dragging my butt outside in the heat and playing with the 
flux core welding gun.  In that time I have gained some perspective on just how 
much work making a decent weld is.

At first I was just banging about with the gun and burning through wire and 
sheet metal.  It was really nasty, but I got a feel for the machine and the 
gun.  Having the old brake rotor to play with allowed me to get comfortable 
that I could lay down a good bead, but it seemed only on a heavy bit of iron, 
not something thin, like what I need to know so I can repair the rusted and 
rotted out floors in the 300D.  SO, zapping thick metal is eazy peezy and most 
any monkey can do that.

I also found that flux core is not good to try to start and stop.  It took me a 
bit to understand that the slag and cruft impedes a good weld, so you need to 
clean the prior muck before you go at it again.  Getting it back to bare metal 
would let the new bead adhere and flow instead of spattering out pellet of 
micro death all over the world.  Flux is great for outdoor work, which the car 
repair will be.  No need to worry the wind is blowing my shielding gas away and 
the air flow also will make the toxic fumes move away from the work.  That is a 
plus.

The HF welding toy is very basic and binary.  You have either BIG amp or small 
amp button and a spastic wire feed control.  The little graphic under the hood 
tells you if you need BIG or small and what wire speed for what thickness of 
metal.  It lies and is very optimistic when dealing with thin sheet metal.  At 
least if you expect to be laying down a continuous bead.  I could not keep from 
blowing through the metal and having bad welds at the 0.5 wire speed (0-9 
range) the graphic depicts.  I up the speed and it still blows out, but at 
least the wire feeds.  The slow speed would not put out wire dependably.  

The solution to that was to not try to make a bead, but to just put a bunch or 
tacks all over the piece and then go back and put some more next to the last 
ones.  Refer to cleaning the old slag above, and my attempts were more 
successful.  That took a long time to figure out.  It also stopped the blow 
outs, warpage and other troubles that build up of excess heat was causing.  Go 
slowly with lots of stitches from quick little spots of heat.  What I also 
garnered from this learning curve was that the really hefty copper welding heat 
sink could suck calories out of the work.  I do not have enough hands to hold 
that and the gun, but it was eye opening.

I am fairly certain all this information was provided by Grant a week ago, but 
seeing it with ones own eyes drives it home.  Much of my practice metal has 
been dead computer cases.  It had a plethora of coatings, and even some of the 
metal I picked up at the scrap store had a film.  For a very good end product, 
you need a VERY clean work surface.  Initially, the wire wheel and grinder 
elbow grease I applied was not enough to really give me a clean, bare surface.  
I thought it looked bare, but it was not.  SHINY metal is a clean, bare 
surface.  No shine, not clean, no good welds will come.  All the youtube videos 
and written explanations did not get that to sink in.  Seeing it in action was 
the key.

The current steep learning curve involves welding sheet metal to a thicker L 
bit.  The heavy L is rather solid and flat.  The body panels I need to tack it 
and weld to are not so flat.  Gaps and uneven contact are not making for a good 
weld.  I am still on the learning bench, not in actual car process.  The sheet 
metal is 18 gauge, the L is 1/8 to 3/16.  


clay 

2002 s430 - Victor, a Stately & well tailored chap
1974 450sl -  Frosch - Two tone green
1976 300D - Blei Vanst - it looks silvery
1972 220D - Gump - She was green, simple and ran
1995 E300D - Gave her life to save me against a Dame in a SUV
POS 1987 SDL - Beware Nigerian Scammers








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