Norman, The brake lines are a low grade of stainless steel, meaning they glow red at a lower temperature than mild steel.
The braze alloy reached its melt temp. but not its flow temp. For practice, you should start by coating a piece of steel with braze. The braze should not be melted directly with the torch, it should be melted with contact with the hot steel. While heeting the steel, a small amount of flux should be melted onto the steel, also NOT melted directly with the torch. Test the temp. of the steel by touching the braze to the steel, when the braze melts and flows you have enough heat to coat the parts. After the parts are coated, allow them to cool so the braze is solid. Then reheat, reflux and test the temperature with the rod until the braze melts without flowing and then fill the gap. If the temp gets to high and the braze starts to flow, remove the heat, allow to cool. Once the braze has melted and cooled it requires a higher temperature to remelt. If you are not using a pair of oxyfuel welding goggles, find a pair, use them. The flame and glowing steel are hard on the eyes(you will destroy your night vision and worse) and the brazing process is easier to watch with goggles. Good luck Darrin Smith ----- Original Message ----- From: Norman James To: [email protected] Sent: Sunday, June 17, 2012 3:35 PM Subject: [TANKS] Brazing, Round 1. AKA Oooo! Glow-ey Hot Stuff! First go at it. Given large coiled sections of brakeline are cheaper, the working medium is a 25 foot section of 5/16ths coated steel brakeline from Auto-zone: costing a grand total of some $20. While in lengths, it’s fairly flexible, I hacked off a ~4 inch and ~2 inch chunk to test with. The brass brazing rods were flux coated, so I didn’t bother with fluxing the joint, but I did grind off the anti-corrosion coating to get down to the base metal with some emery paper. Also, a cut-off wheel mounted in a hand drill was very useful for fish-mouthing the end of the test piece for a nice, clean fit. Note to self: Buy one of those sparky things. Matches don’t work well for lighting torches. Heating up was fairly straightforward, getting the metal a nice glowing orangy-red. And… That’s about where the easy bits ended. The brass rod melted down easy enough, but instead of nicely slipping into the joint (like when working plumbing joints), it kind of globbed up, and dripped off in useless blobs. Using plyers, I flipped it over and blobbed some on the other side with much the same results. I then attempted to overheat the joint, to try and (maybe) melt the blobs soft enough to run into the joint, but nothing doing: the torch just doesn’t look to have the heat to get the thing done. Letting it cool, the joint did appear to hold, meaning there must have been SOME adhesion there, despite the joint resembling a gold version of something I might have blown out of my nose. Simple hand torquing was able to snap the joint relatively easily. Conclusion: More head scratching, and perhaps try something with a melting temp less than 1600 degrees. I found some good alloy brazing rods at a local Ferguson’s with 15% silver content, and a working temp of “only” 480 degrees, so I’ll be giving that a try next. (Yes, I have a much better camera, but it was AWOL. So I used the computer's Logitech chat camera for the pics. Better quality next time) -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat ------------------------------------------------------------------------------ No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2178 / Virus Database: 2433/5077 - Release Date: 06/18/12 -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat
