HF Alumiweld rods for joining AL sheet?

[woodchucker]

I used the Hobart stuff to make my follow rest. I did bevel it as I wanted a flat joint. The only danger is heating the base metal too much. Even using mapp, it's easy to do. I got the rods to fix a garage sale band saw that had a gear box on it. The damn thing had so many cracks......

Anway, the brazes came out great. last pick in #13, and 14

South Bend Lathe 9 Need an opinion of drilling the carriage for a left side follow rest.

That works well, but you can also just turn the QC tool holder around so that one of the dovetails face to the right to mount the tool right under the FR jaw or very near to it, this does make the locking handle sit in an inconvenient location, but I just remove it temporarily. well, since I...

www.hobby-machinist.com

 

[C-Bag]

My OA trek was more convoluted. I took an angle and a piece of the sheet and cleaned them up. I used my smallest torch tip on my regular OA torch and tried to make a bead and what a mess. No matter how much I seemed to throttle back the torch it still blobbed it up. No penetration or stick. So I decided to get out my old acetylene plumbers torch. No cigar, seemed the opposite problem where it didn’t seem to be getting hot enough.

Supposedly you heat the AL and if above 700f just touching the Alumaweld rod to the place to be welded it should melt. I don’t have propane torch so decided it was time to finally get out the little Mecco torch. Dialed it back on the O and A pressures and remembered a trick a member reminded me of. Take just the acetylene flame with the soot and run it over the area to weld. Then go back to a regular OA flame. The soot burns off at 700f so using that as a guide (which I was really having a problem seeing when it was hot enough) pushed the rod in and whatdoyaknow it flowed right in! The other really hard thing for me to get used to is unlike braze or solder AL won’t flow to the heat. They explain in the Alumaweld pamphlet you use the rod to kinda scrape it in. Still kinda thick but finally a strong weld that’s stronger than the parent metal.

 

[woodchucker]

yep, you are not sweating, you need to rub it. I found that out this time too, as it was over a year since the last time I used it. I sweat pipes more than I braze the Al so I had forgotten that. but playing with it I figured it out. It also helps having a infrared thermometer. I don't have OA here.

 

[C-Bag]

I was using a cheapo infrared thermometer and it wasn’t working right. Dunno if it was the thermometer or funky batteries. That’s when I remembered the soot trick. Works perfect. Now just need to get a couple more practice pieces and get it consistent.

 

[jwmelvin]

I was using a cheapo infrared thermometer and it wasn’t working right.

Did you try the IR thermometer after the soot burned off? I’d be curious what it read. Aluminum should be a tough surface to get an accurate temperature with IR, as I think they are usually tuned for emissivity of 0.95 or so. Bare Al is way below that.

(I imagine a reading from the soot-covered surface would be pretty accurate.)

 

[C-Bag]

Did you try the IR thermometer after the soot burned off? I’d be curious what it read. Aluminum should be a tough surface to get an accurate temperature with IR, as I think they are usually tuned for emissivity of 0.95 or so. Bare Al is way below that.

(I imagine a reading from the soot-covered surface would be pretty accurate.)

No I didn’t. As usual when it’s not really giving me what I want I abandon it. But your assessment could explain part of my problem. The pointer laser wasn’t working consistent so that’s what made me think the button batteries were kaput. The soot was very accurate in showing where the AL was up to temp. The problem is once it burns off it’s gone. Maybe once I get more experience with this I won’t feel so frantic as it seems things go from 0 to meltdown in a heartbeat.