Well I could not leave well enough alone! If it ain't broke, fix it til it is, right???
I decided to tig weld the cracks that formed in the shoulders of the swivel jaw race. Both sides were cracked and I want this vise to be a user until I come across a 6" inch Athol or Starrett.
Using a 10x loupe I chased down the tail of the crack and drilled a termination hole. I did a quick wire brushing of the immediate area surrounding the crack, to prevent any old paint from fuming while welding. Then I hogged out a deep v shaped valley to make weld passes in with a tapered tungsten carbide dremel bit. I followed that up with some hand filing to create even consistent valley shoulders to keep the heat zone as consistent as possible.
I live in Washington State and there happens to be a company near me that specializes in selling various soldering, brazing and welding fillers specifically designed for repairing cast iron items. Mike at Muggy Weld suggested I use their "77 cast iron weld" filler rod 3/32" diameter after I determined that the vise was likely made of a form of gray cast iron. The filler rod is designed for stick welding so in order to use it for tig welding the outer coating needs to be removed by soaking in water then scraping clean while still submerged. After scraping I cleaned the filler rod a bit more with fine sandpaper then wiped it clean with rubbing alcohol.
Welding cast iron is tricky no matter what, so I expected impurities and porosity and planned to ebb and flow with the additional complications as they came along. My goal was strength before beauty.
Short 1/2" long weld passes and substantial peening of the weld immediately after each pass is critical to prevent the weld from cracking while cooling. So I made sure to have my ball peen hammer and a nail punch ready, ( the punch is to reach into the valley where the ball peen hammer wouldnt quite fit during the root pass) I warmed up the immediate weld zone with a map/oxy torch on low heat for only a minute or two just to warm things up, there is no need to heat the entire part with this filler.
For starters, I'm a hack welder at best and the welding process was tricky for me as expected. I ended up running at 90 amps for the deep root weld and then backed off to 80 amps for the final 2 passes. Straight Argon gas. Getting each side of the cast iron valley to accept the filler was tricky, but with a bit of throttle control and weaving it worked really well. After the valley was filled I carefully filled the best I could, the cosmetic low spots caused by porosity in the cast iron using about 70-75 amps throttled on the foot. Again peening after every 1/2" pass.
Immediately after all welding was done I peened the entire weld lightly for another minute or so while it was still hot.
Once cooled, I ground the welds down to meet the cast surfaces. I still need to touch up the inner shoulders of the round race, which will be easy with my hand held milling machine(hand files)
For now I decided to not weld the inside of the race as I think it may actually do more damage than good.
Next up for this old chomper is to tune the swivel jaw to "swivel" a touch more freely and then shim the lower slide race to remove some of the jiggle.
