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Discussion Starter · #1 · (Edited)
(OK ..Imagine I sounded like Jerry Seinfeld when I wrote that)

Anyways, I know that pinholes in a TIG bead is a bad thing. I have a few questions regarding them.
1) I know that it's caused by bad technique. I think I remember being taught that when you get to the end of a "run", you back track a bit and gently and evenly let up on the pedal. Is this the correct technique? Or should I be doing something else to begin with?2) Is it OK to go back and "fill" them? Structurally is there anything wrong with this?

Just practiced making pencil holders using flat stock and scraptubing from our esteemed mod., Walt (nothing says happy holidays like getting a poorly welded pencil holder). Up to this point I've just been running straight beads. BIG difference. Now I gotta work more on filling the holes I blow into the tubes :madman: ....
 

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Todd,

Welcome to the learning curve :thumbsup:

Pinholes can be caused by many factors; contamination, internal pressure release, or "cratering" from rapid reduction of heat input.

Here's the deal...clean your tubes with 80 grit, then 180, scotchbright and dip in a degreaser like alcohol or acetone.

Insure that your structure is vented so that internal gases have room to expand without back feeding through your puddle.

Insure you have tight miters and solid fixturing and focus your heat imput to disperse the majority of the energy to the thicker material, catching and allowing the thinner material to puddle and become inclusive in the bead.

Watch your bead...it should move steadily forward having consistent edges and flow smoothly from base material, over the bead, and to the other base material without undercutting or bulging. Think smooth!

At the end of your "run", gently taper off your heat imput with your pedal til the arc dissapears. There should be only the smallest perceptable surface irregularity and no depression at all...think of it as a ripple on the surface of a puddle that is instantly frozen in place. When continuing my bead, I will start back two "puddles", increase the heat until the puddle is encased, then move forward.

The secrete to creating all this? Lot's of practice.

Good luck,

rody
 

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Impurities expand!

Anything that isn't steel that you weld over tends to want to, well, violently explode when it's heated up to that kind of temperature. So that's probably your problem.

A few simple tips:
-Use a gas lens.
-Try lots of different cups and tungsten sizes (well, you probably want 1/16 or 3/32) to see what works best for you. Those things are cheap, just get every size available and try 'em.
- Play with the angle you hold the torch at and the argon flow rate and see what happens.
- Backpurge, if you have the equipment. Helps a lot with blowing holes (well, not blowing holes) and IMO makes things easier.
-Make sure you've got some way for hot gases to vent out of the structure.
-Make sure the workpiece is at a good angle and in a location where it's comfortable to weld and easy to see. Stop and start more often than you might think you need to in order to keep things in a good position. As you get better, you'll be able to weld at weirder angles and with less visibility.
-Wear really thin gloves. I use cotton gardening gloves. Big leather welding gloves are overkill in terms of protection and really hamper your dexterity.

-Walt

toddre said:
Thanks for the input. I do admit that I wasn't very diligent in the cleaning of me tubes.
What causes the pinholes though?
 

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Discussion Starter · #5 ·
Walt said:
Anything that isn't steel that you weld over tends to want to, well, violently explode when it's heated up to that kind of temperature. So that's probably your problem.

A few simple tips:
-Use a gas lens.
-Try lots of different cups and tungsten sizes (well, you probably want 1/16 or 3/32) to see what works best for you. Those things are cheap, just get every size available and try 'em.
- Play with the angle you hold the torch at and the argon flow rate and see what happens.
- Backpurge, if you have the equipment. Helps a lot with blowing holes (well, not blowing holes) and IMO makes things easier.
-Make sure you've got some way for hot gases to vent out of the structure.
-Make sure the workpiece is at a good angle and in a location where it's comfortable to weld and easy to see. Stop and start more often than you might think you need to in order to keep things in a good position. As you get better, you'll be able to weld at weirder angles and with less visibility.
-Wear really thin gloves. I use cotton gardening gloves. Big leather welding gloves are overkill in terms of protection and really hamper your dexterity.

-Walt
Thanks for the tips.
I think my bigest problem was keeping the tungsten "perpendicular" to the joint. I found myslf "laying" it along the joint there fore having a tough time controling the heat.
I will have to be more vigilant in my tube cleaning, too.
What size cups are you folks using?
 

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I just gotta say that it is cool to hear that you are practicing and welding Toddre!! Practice Practice Practice. And the helpful feedback from the likes of Rody and Walt - now that's just downright super cool you guys!!!

I like this forum - I'm no builder, but I love seeing and hearing from the likes of those who are and those who wannabe!
 
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