Weld stops telescoping of barrel and plunger
Hi. I’ve been trying to build the injection machine, but am having problems. Once, I weld the 2 mounting flat bars to the barrel, the plunger no longer telescopes. (I did three small TIG welds on each mount.) My first attempt ended with a stuck plunger. My second attempt is also close to getting stuck, but I pulled the plunger out in time.
I sanded the plunger and tried to hone the barrel with a brake cylinder hone (along with cutting fluid), but I don’t think that the hone was coarse enough to increase the barrel diameter.
Any suggestions on how to bore the pipe out? Worst case, I can buy a third barrel, but is there a trick to reducing the pipe distortion during welding?
Thanks. Actually, I don’t have a MIG welder. I have a DC TIG/stick welder. Is stick okay with electrode-positive for a cooler work piece?
Update: I tried once more with TIG. I lowered the current by going to flat DC instead of pulsed. Dropped the rod size, and did the welds in two shifts to allow cooling in between. The plunger is working fine! Lesson for me in welding distortion. Thanks again.
PS. If anyone finds this in future, I used 100A with 3/32″ ER70S-2 rod and 3/32″ ceriated electrode with lens at 15 CFM pure argon. Barrel is cold-rolled tube 1026 DOM 1.250″ x 0.120″. Welder is Hitbox TIG 180A running on 240V.
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