This week thought I would be practicing some welding skills and trying to improve my technique in something that I had previously learned. I still have a lot more “expert hours” to log before my welds start looking acceptable, but I decided to try just one more style of welding.
You see, I’ve got some wood working lathes in my shop, and there’s a part called the “tool rest” (see photo) on all of them. Well, some of those students, you know the ones we love having in class so much, decided to break the only large tool rest in the shop and not tell me about it.
You see, I’ve got some wood working lathes in my shop, and there’s a part called the “tool rest” (see photo) on all of them. Well, some of those students, you know the ones we love having in class so much, decided to break the only large tool rest in the shop and not tell me about it.
Because the rest is made of cast iron, a very hard but brittle metal, it snapped instead of bending right at the post. And while I could try to weld it with the regular welder, my dad mentioned that I would get a much stronger bond if I were to use a technique called “brazing”.
Brazing uses the heat of a torch to melt the welding material instead of electricity like the other methods I’ve learned.
Brazing uses the heat of a torch to melt the welding material instead of electricity like the other methods I’ve learned.
My dad also gave me a quick rundown of the process: the metal must be preheated then hit with the torch until it becomes red hot. Then you touch the welding rod to the hot area and voila! Turns out it sounds much easier than it really is…
I cut a groove around the crack to give the welding material somewhere to go, clamped it down to the metal table, and then started heating it up with the torch. I think this was my first mistake; the metal table acts like a heat sink and slows down the heating process.
I should have used firebricks like the ones in the picture to help trap the heat.
I should have used firebricks like the ones in the picture to help trap the heat.
My next mistake was not heating the metal up long enough. I just kept thinking it was taking longer than it really should. After about five minutes I just gave it a shot and wasn’t able to get the rod to melt. After a few more minutes of trying, I thought maybe I didn’t have enough information and decided to do some more research.
I watched a few videos and read some articles and came to the conclusion that everything my dad had told me about how to do the brazing was exactly right (imagine that, our parents sometimes know what they’re talking about!) and I just needed to continue to apply heat. Lesson learned.
This week I’ve been thinking more about the Zone of Proximal Development that we read about earlier in the semester and the effect it has on our learning. When my dad gave me instructions on how to braze cast iron, it was kind of in passing and we didn’t get to spend much time on it. I decided to take it on myself without an experienced person to help me, and can say that I have seen the benefits of having someone there to lead you. In my case, the learning experience has taken longer than it should and it clearly less profound. |