Probably not the best forum for this post, but I'm not eligible for access to the 'pro' section yet...
I'm about halfway through my local community college's first HVAC/R course, and we're practicing soldering. I've done plumbing work for years and thought I'd be pretty good, but I'm having a hard time (then again, I don't remember anyone ripping my solder joints apart before and critiquing them, so maybe I was never as good as I thought).
I seem to have two major problems. The first is using just a little too much solder, especially on the 1/4" tube, but really all the way up to 1/2"--do any of you old hands have any guidelines on how to tell when it's enough without over-doing it?
My second problem is with bare spots on the copper, where the solder doesn't stick. It's got to be hot enough--it's surrounded by good coverage, so I'm thinking that there's oil or something on the copper. We're cleaning the tube with emery cloth, but I wonder if I'm getting oil or some other contaminant from my skin onto the copper while I'm cutting and swaging it. They're short (2") pieces, so it's tough to completely avoid handling it. Any other advice here?
Is there any flux/solder/refrigerant safe solvent that can be used to clean oil, etc., off the tube before sanding it?
We're using Stay-Brite 8 and a paste flux from Harris.