Tig welding tips, questions, equipment, applications, instructions, techniques, tig welding machines, troubleshooting tig welding process
timmy
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Hi all, I'm looking for some advice. What I'm trying to do is to weld a 3/32" pin into a blind hole so that it can not come out. The part with the hole is 17-4 stainless. #3 shows someone doing what I'm talking about, they have the pin is slightly recessed. They are using a stainless pin (not welding rod). #4 shows the finished results, from what I see I don't think they are using any filler rod.

In the past I have used drill rod for the pin which has worked sometimes, I've been trying to get away from that since it hardens when welded so it is too hard to drill/mill when removal is required. I am currently using 316 stainless welding rod for the pin. I have also tried various stainless steel alloys for pins.

My original way of doing these was to use a fixture that I made that would hold my torch straight up and down over the pin, it would hold it in place and I could adjust it so I had approx. 0.100" clearance. I would have the pin slightly above the surface and basically use that as filler, it seems that when I have tried to add filler I end up an irregular weld instead of the small circle that I"m trying to get. Picture #1 would be with this setup. To weld I would just increase amperage with the dial on the machine until it appears to have a nice puddle, back it down and turn off. I'm using a harbor freight welder with very little adjustment other than amperage. I have since added a foot pedal since I have been trying to weld by hand instead of the fixture, I was hoping that being able to move the torch would allow me to put more heat on to the spot that wasn't getting welded. Picture #2 shows this problem. I will get one small spot that doesn't weld. When using my fixture I would have to move it so that the tungsten is over the spot and hit it again. Sometimes this would work but either way I usually end up with a not so good looking weld.

I have an acquaintance that does these jobs and said that they use welding rod and cut it so that the pin is below the surface. They will add a dab of filler rod to capture the pin and be done. I have a local welder that also suggested the filler rod since the silicon in it will allow it to flow better.

In the past I was using a 1/16" tungsten but have been using 0.040" lately. As you can see in picture #2 there is a sharp corner to the right of the weld that is easy to melt by accident. I have upgrade my torch head so now I have a gas lens.

I'm basically looking for any tip on how you would do these such as tungsten size, max amperage, etc., especially what you would do if are ending up with #2. More heat? Move tungsten around at a lower heat?
cj737
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    Thu Sep 29, 2016 8:59 am

recess the pin, use a small diameter filler rod, weld the rod to the pin/sidewall as your friend suggested. The welded fillet stays below the top surface, capturing the pin. The diameter of your tungsten isn't the issue; its likely the taper and the stick out length. A larger cup provides more gas coverage (something stainless wants badly). You'll need some decent amperage due to the thickness of the part in order to get the weld to flow. You can use the pedal to back off once you get it started.

You can also weld in small sections. Re-position, weld again. Re-position, etc. This allows you to have better visibility and control of the arc angle.
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Regarding pic #2, my first weld would be on the side that is closest to the edge, get that done while the part is cold, the rest is cake.
Richard
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timmy
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    Sun Jan 21, 2018 2:10 pm

Thanks for the replies. Below is the next one that I have to do. This one came pre-drilled and with a pin that is recessed so I can definitely try the suggestions.

Here's some more info about my setup/process:

Tungsten 0.040", ground to a point, grind length 2-3x diameter (yes, needs reground in pic). Sticking out 1/4".
Gas lens
#8 cup
we increased gas flow with the gas lens, appears to be 40 cuft/hr.
start amperage 10, I usually try to keep the max under 60

Gas flow too high? I wonder if we were reading the wrong scale on the dial since 20 is the number in my head.
Should I concentrate heat in hole or move around perimeter?
Since I'm not laying a bead is it ok to keep the torch head vertical?
As far as amperage goes would you hit it hot and fast or low and longer?
Any idea what the max amps you'd need for these? I can set a mechanical stop on my foot pedal.
Any suggestion on filler rod size?
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Last edited by timmy on Mon Jan 22, 2018 4:03 pm, edited 1 time in total.
aland
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    Thu Dec 28, 2017 11:10 pm

Hah! Looks like barrel extension and muzzle brake/flash-hider.

I know they must be pinned if the barrel is less than min-length when removed, so thanks for posting this thread, I've not done one yet as all my barrels are past min-length without the brake.

I have a question which I hope you don't mind me asking. How do you set/measure the headspace when you weld on the extension?

Alan
cj737
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    Thu Sep 29, 2016 8:59 am

[quote="timmy"]
Here's some more info about my setup/process:

Tungsten 0.040", ground to a point, grind length 2-3x diameter (yes, needs reground in pic). Sticking out 1/4". Personally, I'd never use less than a 3/32 tungsten.
Gas lens
#8 cup
we increased gas flow with the gas lens, appears to be 40 cuft/hr. This is very high. 20CFH should be all you need.
start amperage 10, I usually try to keep the max under 60

Gas flow too high? I wonder if we were reading the wrong scale on the dial since 20 is the number in my head.
Should I concentrate heat in hole or move around perimeter? I'd focus my arc on the pin and pin/hole surface.
Since I'm not laying a bead is it ok to keep the torch head vertical? Always, just as long as you can see.
As far as amperage goes would you hit it hot and fast or low and longer? Personally, I'd ramp up to find the spot where it flows, then move. Taper off gently and perhaps wave the arc back-forth along the weld.
Any idea what the max amps you'd need for these? I can set a mechanical stop on my foot pedal.
Any suggestion on filler rod size? 0.030 MIG wire would work great. ER70S-2

There's my opinion to your questions.
timmy
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    Sun Jan 21, 2018 2:10 pm

aland wrote:Hah! Looks like barrel extension and muzzle brake/flash-hider.

I know they must be pinned if the barrel is less than min-length when removed, so thanks for posting this thread, I've not done one yet as all my barrels are past min-length without the brake.

I have a question which I hope you don't mind me asking. How do you set/measure the headspace when you weld on the extension?

Alan
Yes, it is. I think you're a bit mixed up on your terms. Headspace has nothing to do with this end of the barrel. If you mean overall length the barrel is a known length of 14.5" and muzzle device is designed to add enough to get it to 16".
timmy
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    Sun Jan 21, 2018 2:10 pm

cj737 wrote:There's my opinion to your questions.
Thank you, I have to think that the excess gas could be part or a lot of the reason I seem to have a hard time getting enough heat right at the weld. I'll cut that in half and also go back to the 1/16" tungsten, I'll see if I have any 3/32". I was going small to try and keep the heat near the weld and to avoid discoloring the black oxide coating but it does seem like I keep balling up the tungsten since I'm having to put more amps to it.

I think the mig wire I've been playing around with is about 0.030" so I'll play with some scrap and see if things are working better than they have been.
aland
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    Thu Dec 28, 2017 11:10 pm

timmy wrote:Yes, it is. I think you're a bit mixed up on your terms. Headspace has nothing to do with this end of the barrel.
Isn't your first picture the barrel extension on the rear where the round chambers? I thought pic 3/4 in your first post was the barrel extension. All the barrels I've bought had the extension on them, was just curious how you adjust it to measure before you weld it up. I know how to measure the head space after it is assembled. If that is not the extension, ignore my question.
timmy wrote:If you mean overall length the barrel is a known length of 14.5" and muzzle device is designed to add enough to get it to 16".
For the brake/flash-hider yes. My question was in regard to adding the barrel extension on the rear of the barrel, but no worries I'm not doing that and was just curious. :roll:

Alan
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