The Big Think

May 30, 2016

R2 – First Welds!

Filed under: Uncategorized — jasony @ 9:06 am

I met with Keith at Techshop yesterday for a 2 hour TIG welding master class. The guy is a riot of old-school enthusiasm and energy and I learned a lot from him. At the starts of the session I showed him my practice welds (I have a plate of about 20 welds on it that I’m particularly proud of) and wanted to spend the time taking about the pieces I’d brought and how I would eventually weld them together. What does he see when he sees those pieces? How does an experienced welder view a part? What’s the best approach for clamping? What about cool down time?

He’d have none of this “planning” stuff.

Instead, he looked at my test piece with approval, said “you can weld”, then chucked the test piece aside, grabbed the horseshoe pieces, and said “you’re going to weld this…. right now”.

And so I did.

He did the first couple of tack welds to hold the part together, get things heated up (welding a part is much easier when it’s already hot), and generally give me a start, and then he handed me the torch and we went after it. If I made a slight mistake he jumped in and either corrected it or talked me through how to fix it, and then handed the torch back to me.

Over the next two hours we welded up the horse shoe and then aligned and welded up the center ankle. I feel really good about how things went, especially considering the fact that I didn’t think I’d be working on actual parts for a few weeks. Keith is a “get ‘er done” sort of guy that encourages students to jump in there and start even if they don’t know everything. I’m much more careful about parts that I’ve spent months and lots of money making, but Keith is kind of a whirlwind that you just get sucked up behind.

The hardest part of the process was the angles and orientation. I’d been planning on carefully laying out the parts so that the joint to be welded was flat and parallel to the ground. That way I could approach the weld exactly like I’ve done each weld in practice. Keith’s attitude was this is real welding! and he’d proceed to put the joint at some funky angle and then challenge me to do it. Sideways, angled, even upside-down at one point! Really awkward and tough stuff. And this was on my actual parts! It really freaked me out, but like I said, he was there to correct things when I got them wrong.

And boy,did I ugly up some of the welds. Black, splotchy, butt-ugly welds. They’re strong enough, sure, but I’ll be spending some real quality time with the grinder once I clean them up. Keith kept saying “don’t worry! You’ll improve!” and I kept saying “but I could do this if we could just lay it out flat!”. He’s respond with “no way! This is REAL welding!” and then make me bend myself into some impossible orientation to get ‘er done. It was stressful, but I learned a lot from the experience. The chief thing I learned was that, unless you completely destroy the metal with heat, you can fix just about any bad weld. Keith didn’t do much cleaning or anything and still managed some good welds. We talked pedal control, getting REALLY close to the puddle (he was probably 1/32nd from the weld with the tungsten!), using a different tungsten (I’d been using the red 2% thoriated and he recommended the purple 2% seriated because it holds a cleaner and more consistent arc), speed, power (150 amps!) and other stuff.

I got a couple of decent tingle/zaps from the setup when my left hand got soaked with sweat inside the glove. With 150 amps of 6v electricity, even with protective gear, getting a damp hand in the current can cause some discomfort. It didn’t hurt as much as it was just unpleasant. Some tingling like touching a 9 volt with your tongue. Lesson here is to take breaks and make sure you’re dry. But that’s hard to do when you’re in the Keith whirlwind.

So I’ve got both horse shoes welded and the center ankle. I’m going to mill up a special part for the center ankle to reinforce the mounting holes. I don’t think the 1/8″ of aluminum there is strong enough if R2 hits a good bump. It’s technically an “off spec” part but it’ll be hidden underneath R2 way up inside along the bottom of the frame so I don’t care. Better that than have the whole ankle shear away. An extra 1/4″ of aluminum there should work nicely.

No pics on these parts yet. I can’t have my expensive iPhone in my pocket when I weld lest I zap it. And usually I’m so tired and grubby after a 4 hour session that I just want to get home and take a shower. I’ll take pics later.

Next step is to do the outer ankles. I feel really good about my approach now that I’ve watched Keith do it. Then I’ll weld up the leg assemblies and then maybe the feet. I’ll leave the battery boxes for the end since they’re going to be a real challenge to align and tack up without them warping all over the place. Slowly, slowly.

Onward!

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