Part 2) I don't seem able to add more than one photograph.

I have a 50 year old Hyster P50A forklift that I'm restoring. I've found that some of the fixed hydraulic tube has deteriorated over time. Tubes and hoses flex in amongst hydraulic mud and wear away particularly at the steel tubing. This is exactly the same situation as Jody was describing in this video: Silicon Bronze TIG Brazing (youtube.com)

This part of the steering tube had worn away to the point of rupture. While I will replace the tubing into the future, I firstly need to recover the forklift from a paddock, in the middle of nowhere. The tubes are complex shapes and really need fitting properly. I need to fix the lines in the first instance.

Part 2..... and this is the other.

Both images occurred within a couple of seconds of each other. I just kept stop/starting to find two clear examples.

Seemingly, the inner cone remains quite constant while the outer cone is additional. It seems to appear and disappear. I've never been able to observe that buy starting / stopping a video before. Electrically, I have a few theories about what's occurring here with electrons and ions etc.

I wonder if Brad and Johannes have ever observed these kinds of effects before. I know they both have welders with AC amplitude (current) adjustment for each cycle. I wonder of those adjustments can be observed in an arc image like these.

I have a pretty good Speedglas shield but I've never seen anything to this level of detail.

Hi Jody,

Thanks for the video and comments regarding the feeding of filler. It's such a struggle to begin TIG welding when this is not automatic. Any ideas are always valuable.

I'd like to comment on the arc shots. They are the clearest I've ever seen. I've been studying what's going on within the arc for some time. Stopping and starting the video revealed possibly the two stages of AC waveform and the effect on the arc.

I screen grabbed two instances from the same section of video. This is one....

JD BrewerYes, 309 was good... until it wasn't. It's expansion and contraction just seemed to strong for the cast iron to handle. It began quite obviously peeling up and ripping itself away from the cast iron.

I wonder if anyone else has observed this with a 309 pad up on cast iron before?

JD Brewer Yes, it worked well. After doing a few, I worked out something quite important. If you can start by SilBro-ing the bottom corners of slot together first, that's an advantage.

From that point, the heat seems to travel equally into both the bottom and sides of the slot. From there, you can just fill it up.

I had to be very careful not to go near the top edges (of the slot) with the arc. It was very easy to nip into those edges. I was trying to keep the slot as rectangular as possible.

I just used a sharpened tungsten and acetone to clean into those corners, bottom  and sides first.

I found that a flap disk was very effective in levelling the SilBro. The flap disk would go down to the mill-scale level easily, then slide across the top of the mill-scale. The mill-scale became a useful guide to level out the SilBro.

Hi JD,  I'm no expert but, I read and think that super clean is an advantage for the SilBro bond with the base metal. Speaking with my son ( the Chemist ), these are metallic bonds between the iron and the copper. They give up and take electrons etc.

This is bizarre but metals can apparently dissolve other metals and I believe that's what's occurring at the boundary between them. See the mercury dissolve the gold here: Dissolving gold in mercury - YouTube

I think that a more finely sanded surface would tend to be cleaner??? A more coarsely sanded surface would have more surface area??? Which is ultimately stronger???

Hi JD, I had this welding table laser cut. I TIG welded it mostly from the inside but wanted to fill the top tab cavities with something, so they didn't collect garbage.

Welding the cavities would no doubt have worked well. I didn't need that level of strength and didn't want' to introduce any more heat than necessary.

The answer was SilBro again, and it was easier to grind down with a flap disk.