Guide me to bumping technique.

[steph]

Hi all,
Tried the bumping tech yesterday, the material is a broken car velg, anodized like a mirror, thickness about 5-6mm. I used Syncrowave 250DX, the settings are: 8LPM 100% Argon, 3/32 1,5% Lant tung, gas lens with cup #6, WP18, 150Amps, balance at 4 (balanced?), wiped with thinner (got no acetone here). I can get a puddle in about 2-3secs, it's a clean puddle.
The problem is when I dab the filler (4043) for the second time. The puddle will soon contaminated (looks skinny). No problem when first time dab. The cleaning area not seen.
The question is what did I do wrong? Is it normal not to have a cleaning area when bumping the anodized? Maybe the cup was to small? Amp not hi enough?
Any information and suggestion is greatly appreciated. Thank you all in advance.

[Drf255]

Do search the Weldingweb.com for answers.

SundownIII is the "bump welding" anodized pro. If you search his posts and the topic itself, you're likely to get some great info.

[walker]

Whats a car velg?

[Gaby]

Steph i am running a dynasty 350 i use 5356 rods on boat towers. I also run at about 200 to230 depending on the thickness. Bump get a puddle dab bump dab bump etc. The only differance is i use higher setting and a 5356 rod. Good luck

[Gaby]

Also my cleaning is set to 65 % to let the welder work right. En setting advanced square wave. 75 - 25 EN to EP FREQUENCY of 120

[steph]

Ok, guys, thank you all for your reply.

@Walker: Car velg I meant is car wheel. Thought velg is english
@Drf255: thank you for the info
@Gaby: unfortunately I still don't have an inverter.

Still wanna hear from another who bumped the anodized using Sync250DX.

Thank you.

[Portable Welder]

The contamination is probably happening because you are welding a dirty aluminum rim. You have to clean the aluminum.

[cruizer]

Ahhh, preheat and yes the wheel is likely contaminated, wax or other.

[steph]

@gaby: you use 200-230amps on what thickness?
@cruizer: I didnt preheat because I can get a clean puddle in 2-3 seconds. Do I still need a preheat? Maybe I need to change a bigger cup?
@cruizer & portablewelder: whats your suggestion to clean it? I thought thinner will clean the oil and grease well. I didnt stainless brushed it because it looked very clean.

Thank you guys for spending time with me.

[FusionKing]

Dude.....if you are welding on a car wheel.....you need to give us a LOT more info.
Keeping the anodize pretty should be the absolute least of your worries.
This thread is pretty much useless without some sort of decent pics of what you are doing.