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Discussion Starter · #1 ·
Just a quick questions here.

What size filler rod do you use when welding aluminum frames?

1/8" or 3/32"?

I have been using 5356 1/8" on my BMX frames and I think I can smaller.

Thoughts?
 

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RCP Fabrication
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IMO that depends on the welder. The new inverter welders have the ability to really tighten up the arc (and bead) and you can use less (smaller) filler. A transformer machine pumping out 60hz of square (or sine) wave AC with a balled tungsten will have a much wider bead and requires more filler.
 

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Yeah, I'm with Ryan. I'm running a transformer and 3/32" feels best. When I ran my buddy's Dynasty 120 Hz, I felt like 3/32" was a little too big. But 1/8" would be too big for me.
 

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Discussion Starter · #5 ·
I have a miller Miller Diversion 165. I've not done a ton of welding but made a few frames for some small kids. 6 year olds. I'm a dipper and not a really a pusher. My welds tens to "big" meaning almost like a vain with a lot of height.
 

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Discussion Starter · #6 ·
Here are a couple weld pictures. Maybe you can see what I am talking about.

These are all done with 1/8" Filler rod



 

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RCP Fabrication
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Diversions are set at 120hz, 72% DCEN. It's pretty much the sweet spot for good clean aluminum in any position/joint. I would use 3/32" filler from 40 amps to well over 200 with an inverter.

Edit: Just saw the pics, doing exactly what you are doing with a smaller filler rod is going to be an improvement all around.
 

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Discussion Starter · #8 ·
Thanks RCP. I need a little improvement.

I think it will also save me some weight. I know! Not much weight. But when you are competing for lightest bike awards it's important..

Last year there was an article in Pull magazine. "Quest for 6 pound bike" ( or something like that). 6 builders submitted bikes and I made the frame for one of them. Well, my frame was the lightest and now that builder is sending me all his frame business. I sold one a month ago that weighed 1.05 pounds. These are for 3 and 4 year old racers that don't challenge the frame strength at all.
 

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The toe of the weld is the edge of the weld. Washing it in would make a smoother transition from tube to weld. With your welder you are going to have a very hard time laying down a bead like the one Zank posted. Your diversion uses miller's advanced squarewave AC wave shape. It is designed to be a very stiff arc that freezes fast. Nothing wrong with it, but to have the toes wet in you want a softer arc.
 

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Discussion Starter · #12 ·
Let me ask a different question.
Is it possible to weld Aluminum after it has been polished? Or does the polish contaminate the welds?
 

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Discussion Starter · #13 ·
I think a smaller rod and more heat will help get you a more fluid puddle, wash the toe of the weld into the tube a little more smoothly, and smooth out the ripples. Those are the things I focus on.


Trying out a Dynasty by Zanconato Custom Cycles, on Flickr
I am just wondering. What wall thickness are you welding? When I pour the heat to it, my thinner walls melt away. (0.35) I assume that is pretty thin. I am almost always holding my torch on the side completely. I know that is a choice that I am making as a builder and quite frankly it gives me an advantage. However, it may be a sacrifice in the looks of my welds.

What welder would you recommend? I knew that my Diversion was limited. However, at the time it seemed to be exactly what I needed.
 

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Discussion Starter · #15 ·
Yeah I know it's thin. I'm not doing anything. These kids weigh 40 pounds and don't jump it anything. It's more like a road bike being ridden on dirt. I have several frames here ready to do some destructive testing. I'm preparing a jig to hold the frames then going to simulate the bikes being jumped and "cased". I'm still doing some homework on this subject.

Basically I'm going to stress them until failure. Not just my frames but I've collected an Intense, Super Cross and SSquared. Then going to compare my frames with theirs. Once the frames are broke I will cut all of them up and compare tubing thickness.

Make changes accordingly.
 

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with .035 wall tubing you should be using 1/16" filler, and trying to cut your weld size (width and height) down as much as possible.
 

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Discussion Starter · #17 ·
Ok, I made some changes based on the feedback from yesterday. Mainly filler rod and heat. I added more heat. I cant wait to make a bigger frame with out this thin stuff.

The first picture you can see where I changed the heat I was applying. The circle on the right is less amp than the left side.

The 2nd one is just another weld after the "tweak". If you have any more advice that would be great.



 
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