Questions for the welding pros

[MP&C]

Originally Posted by mongocanfly

When I was doing mine ,I used copper everywhere that I could....just for insurance

Greg, we need to talk.... Get rid of the crutch, it's a heat sink..

Originally Posted by A1971Blazer

1/4”

1/4" isn't too awful big, and if you have a center cutting end mill should be able to use it and clean out the paint inside the plug weld holes (slow speed in cordless drill??). I use a Letter A drill bit for most of my plug welds, a bit higher heat, and faster wire feed. Fills quicker, gets done quicker. Hotter weld setting will give you a flatter plug weld for less cleanup. And NO copper backing. You are adding a heat sink that is going to move you back towards a cold weld. The only time a copper backing should be used is when you have thinned metal (rust), pinholes to fill, or an ill-placed gap to fill.


Here's a tutorial on the plug weld bit for cleaning holes. This uses a narrow flat so less likely to remove metal than your end mill. We just want to clean paint out of the hole to improve weld quality.


https://www.youtube.com/watch?v=J1jXNfJj2ac





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